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1.
Mol Cell ; 83(23): 4318-4333.e10, 2023 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-37989319

RESUMEN

RNA unwinding by DExH-type helicases underlies most RNA metabolism and function. It remains unresolved if and how the basic unwinding reaction of helicases is regulated by auxiliary domains. We explored the interplay between the RecA and auxiliary domains of the RNA helicase maleless (MLE) from Drosophila using structural and functional studies. We discovered that MLE exists in a dsRNA-bound open conformation and that the auxiliary dsRBD2 domain aligns the substrate RNA with the accessible helicase tunnel. In an ATP-dependent manner, dsRBD2 associates with the helicase module, leading to tunnel closure around ssRNA. Furthermore, our structures provide a rationale for blunt-ended dsRNA unwinding and 3'-5' translocation by MLE. Structure-based MLE mutations confirm the functional relevance of our model for RNA unwinding. Our findings contribute to our understanding of the fundamental mechanics of auxiliary domains in DExH helicase MLE, which serves as a model for its human ortholog and potential therapeutic target, DHX9/RHA.


Asunto(s)
Proteínas de Drosophila , ARN Helicasas , Animales , Humanos , Proteínas Cromosómicas no Histona/genética , ADN Helicasas/genética , Drosophila/genética , Drosophila/metabolismo , Proteínas de Drosophila/metabolismo , Homeostasis , ARN/metabolismo , ARN Helicasas/metabolismo , ARN Bicatenario/genética , Factores de Transcripción/metabolismo
2.
Nucleic Acids Res ; 52(9): 4889-4905, 2024 May 22.
Artículo en Inglés | MEDLINE | ID: mdl-38407474

RESUMEN

Acetylation of lysine 16 of histone H4 (H4K16ac) stands out among the histone modifications, because it decompacts the chromatin fiber. The metazoan acetyltransferase MOF (KAT8) regulates transcription through H4K16 acetylation. Antibody-based studies had yielded inconclusive results about the selectivity of MOF to acetylate the H4 N-terminus. We used targeted mass spectrometry to examine the activity of MOF in the male-specific lethal core (4-MSL) complex on nucleosome array substrates. This complex is part of the Dosage Compensation Complex (DCC) that activates X-chromosomal genes in male Drosophila. During short reaction times, MOF acetylated H4K16 efficiently and with excellent selectivity. Upon longer incubation, the enzyme progressively acetylated lysines 12, 8 and 5, leading to a mixture of oligo-acetylated H4. Mathematical modeling suggests that MOF recognizes and acetylates H4K16 with high selectivity, but remains substrate-bound and continues to acetylate more N-terminal H4 lysines in a processive manner. The 4-MSL complex lacks non-coding roX RNA, a critical component of the DCC. Remarkably, addition of RNA to the reaction non-specifically suppressed H4 oligo-acetylation in favor of specific H4K16 acetylation. Because RNA destabilizes the MSL-nucleosome interaction in vitro we speculate that RNA accelerates enzyme-substrate turn-over in vivo, thus limiting the processivity of MOF, thereby increasing specific H4K16 acetylation.


Asunto(s)
Proteínas de Drosophila , Histona Acetiltransferasas , Código de Histonas , Animales , Masculino , Acetilación , Drosophila melanogaster/metabolismo , Drosophila melanogaster/genética , Proteínas de Drosophila/metabolismo , Proteínas de Drosophila/genética , Histona Acetiltransferasas/metabolismo , Histona Acetiltransferasas/genética , Histonas/metabolismo , Lisina/metabolismo , Proteínas Nucleares , Nucleosomas/metabolismo , Especificidad por Sustrato , Factores de Transcripción/metabolismo , Factores de Transcripción/genética
3.
Mol Cell ; 60(3): 487-99, 2015 Nov 05.
Artículo en Inglés | MEDLINE | ID: mdl-26545078

RESUMEN

The MLE helicase remodels the roX lncRNAs, enabling the lncRNA-mediated assembly of the Drosophila dosage compensation complex. We identified a stable MLE core comprising the DExH helicase module and two auxiliary domains: a dsRBD and an OB-like fold. MLEcore is an unusual DExH helicase that can unwind blunt-ended RNA duplexes and has specificity for uridine nucleotides. We determined the 2.1 Å resolution structure of MLEcore bound to a U10 RNA and ADP-AlF4. The OB-like and dsRBD folds bind the DExH module and contribute to form the entrance of the helicase channel. Four uridine nucleotides engage in base-specific interactions, rationalizing the conservation of uridine-rich sequences in critical roX substrates. roX2 binding is orchestrated by MLE's auxiliary domains, which is prerequisite for MLE localization to the male X chromosome. The structure visualizes a transition-state mimic of the reaction and suggests how eukaryotic DEAH/RHA helicases couple ATP hydrolysis to RNA translocation.


Asunto(s)
Adenosina Trifosfato/química , Proteínas Cromosómicas no Histona/química , ADN Helicasas/química , Proteínas de Drosophila/química , ARN Helicasas/química , ARN/química , Factores de Transcripción/química , Adenosina Trifosfato/genética , Adenosina Trifosfato/metabolismo , Animales , Proteínas Cromosómicas no Histona/genética , Proteínas Cromosómicas no Histona/metabolismo , ADN Helicasas/genética , ADN Helicasas/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster , Masculino , Estructura Terciaria de Proteína , ARN/genética , ARN/metabolismo , ARN Helicasas/genética , ARN Helicasas/metabolismo , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Relación Estructura-Actividad , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Cromosoma X/química , Cromosoma X/genética , Cromosoma X/metabolismo
4.
Nucleic Acids Res ; 48(13): 7483-7501, 2020 07 27.
Artículo en Inglés | MEDLINE | ID: mdl-32510132

RESUMEN

The MLE DExH helicase and the roX lncRNAs are essential components of the chromatin modifying Dosage Compensation Complex (DCC) in Drosophila. To explore the mechanism of ribonucleoprotein complex assembly, we developed vitRIP, an unbiased, transcriptome-wide in vitro assay that reveals RNA binding specificity. We found that MLE has intrinsic specificity for U-/A-rich sequences and tandem stem-loop structures and binds many RNAs beyond roX in vitro. The selectivity of the helicase for physiological substrates is further enhanced by the core DCC. Unwinding of roX2 by MLE induces a highly selective RNA binding surface in the unstructured C-terminus of the MSL2 subunit and triggers-specific association of MLE and roX2 with the core DCC. The exquisite selectivity of roX2 incorporation into the DCC thus originates from intimate cooperation between the helicase and the core DCC involving two distinct RNA selection principles and their mutual refinement.


Asunto(s)
Ensamble y Desensamble de Cromatina , ARN Largo no Codificante/metabolismo , Transcriptoma , Animales , Proteínas Cromosómicas no Histona/genética , Proteínas Cromosómicas no Histona/metabolismo , Clonación Molecular/métodos , ADN Helicasas/genética , ADN Helicasas/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster , Unión Proteica , ARN Largo no Codificante/genética , Proteínas de Unión al ARN/genética , Proteínas de Unión al ARN/metabolismo , Factores de Transcripción/genética , Factores de Transcripción/metabolismo
5.
Mol Cell ; 51(2): 174-84, 2013 Jul 25.
Artículo en Inglés | MEDLINE | ID: mdl-23870143

RESUMEN

Dosage compensation in Drosophila involves a global activation of genes on the male X chromosome. The activating complex (MSL-DCC) consists of male-specific-lethal (MSL) proteins and two long, noncoding roX RNAs. The roX RNAs are essential for X-chromosomal targeting, but their contributions to MSL-DCC structure and function are enigmatic. Conceivably, the RNA helicase MLE, itself an MSL subunit, is actively involved in incorporating roX into functional DCC. We determined the secondary structure of roX2 and mapped specific interaction sites for MLE in vitro. Upon addition of ATP, MLE disrupted a functionally important stem loop in roX2. This RNA remodeling enhanced specific ATP-dependent association of MSL2, the core subunit of the MSL-DCC, providing a link between roX and MSL subunits. Probing the conformation of roX in vivo revealed a remodeled stem loop in chromatin-bound roX2. The active remodeling of a stable secondary structure by MLE may constitute a rate-limiting step for MSL-DCC assembly.


Asunto(s)
Adenosina Trifosfato/farmacología , Proteínas Cromosómicas no Histona/metabolismo , ADN Helicasas/metabolismo , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , ARN Helicasas/metabolismo , Proteínas de Unión al ARN/genética , ARN/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , Cromosoma X/genética , Animales , Animales Modificados Genéticamente , Emparejamiento Base , Western Blotting , Cromatina/genética , Proteínas Cromosómicas no Histona/genética , ADN Helicasas/genética , Proteínas de Drosophila/química , Drosophila melanogaster/genética , Drosophila melanogaster/crecimiento & desarrollo , Drosophila melanogaster/metabolismo , Ensayo de Cambio de Movilidad Electroforética , Genes DCC/genética , Inmunoprecipitación , Masculino , Mutación/genética , Conformación de Ácido Nucleico , ARN/química , ARN/metabolismo , ARN Helicasas/genética , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/metabolismo , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Factores de Transcripción/química , Transcripción Genética , Cromosoma X/metabolismo
6.
Nucleic Acids Res ; 47(8): 4319-4333, 2019 05 07.
Artículo en Inglés | MEDLINE | ID: mdl-30805612

RESUMEN

Maleless (MLE) is an evolutionary conserved member of the DExH family of helicases in Drosophila. Besides its function in RNA editing and presumably siRNA processing, MLE is best known for its role in remodelling non-coding roX RNA in the context of X chromosome dosage compensation in male flies. MLE and its human orthologue, DHX9 contain two tandem double-stranded RNA binding domains (dsRBDs) located at the N-terminal region. The two dsRBDs are essential for localization of MLE at the X-territory and it is presumed that this involves binding roX secondary structures. However, for dsRBD1 roX RNA binding has so far not been described. Here, we determined the solution NMR structure of dsRBD1 and dsRBD2 of MLE in tandem and investigated its role in double-stranded RNA (dsRNA) binding. Our NMR and SAXS data show that both dsRBDs act as independent structural modules in solution and are canonical, non-sequence-specific dsRBDs featuring non-canonical KKxAXK RNA binding motifs. NMR titrations combined with filter binding experiments and isothermal titration calorimetry (ITC) document the contribution of dsRBD1 to dsRNA binding in vitro. Curiously, dsRBD1 mutants in which dsRNA binding in vitro is strongly compromised do not affect roX2 RNA binding and MLE localization in cells. These data suggest alternative functions for dsRBD1 in vivo.


Asunto(s)
Proteínas Cromosómicas no Histona/química , ADN Helicasas/química , Proteínas de Drosophila/química , Drosophila melanogaster/química , ARN Largo no Codificante/química , Factores de Transcripción/química , Secuencia de Aminoácidos , Animales , Sitios de Unión , Proteínas Cromosómicas no Histona/genética , Proteínas Cromosómicas no Histona/metabolismo , Clonación Molecular , ADN Helicasas/genética , ADN Helicasas/metabolismo , Compensación de Dosificación (Genética) , Motivo de Unión al ARN Bicatenario , Proteínas de Drosophila/genética , Proteínas de Drosophila/metabolismo , Drosophila melanogaster/genética , Drosophila melanogaster/metabolismo , Escherichia coli/genética , Escherichia coli/metabolismo , Expresión Génica , Regulación de la Expresión Génica , Vectores Genéticos/química , Vectores Genéticos/metabolismo , Cinética , Masculino , Modelos Moleculares , Conformación de Ácido Nucleico , Unión Proteica , Conformación Proteica en Hélice alfa , Conformación Proteica en Lámina beta , ARN Largo no Codificante/genética , ARN Largo no Codificante/metabolismo , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Proteínas Recombinantes/metabolismo , Alineación de Secuencia , Homología de Secuencia de Aminoácido , Factores de Transcripción/genética , Factores de Transcripción/metabolismo
7.
Mol Cell ; 48(4): 647-54, 2012 Nov 30.
Artículo en Inglés | MEDLINE | ID: mdl-23084834

RESUMEN

The process of dosage compensation (DC) in Drosophila counterbalances the monosomy of the X chromosome in male flies by increasing the transcription from this unique chromosome in the two-fold range. Upon exclusive expression of male-specific lethal 2 (MSL2) in males, the dosage compensation machinery assembles on active X-chromosomal genes. Overexpression of MSL proteins leads to aberrant binding of complex components to autosomes. Accordingly, MSL levels have to be carefully regulated. Here we describe a new mechanism through which MSL2 can fulfill its role as the central regulator of the faithful biogenesis and functionality of the DC machinery. MSL2 is an E3 ligase that ubiquitylates itself and the other associated components when their stoichiometry is unbalanced, uncovering proteasome-dependent degradation as an additional layer of homeostatic control of MSL levels. Furthermore, systematic mapping of modification sites by mass spectrometry and chromatin interaction studies on the target protein MSL1 suggest that the role of MSL2-mediated ubiquitylation goes beyond proteolysis.


Asunto(s)
Proteínas de Unión al ADN/metabolismo , Compensación de Dosificación (Genética) , Proteínas de Drosophila/metabolismo , Homeostasis , Proteínas Nucleares/metabolismo , Factores de Transcripción/metabolismo , Animales , Células Cultivadas , Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/genética , Proteínas de Drosophila/química , Proteínas de Drosophila/genética , Drosophila melanogaster/química , Drosophila melanogaster/citología , Drosophila melanogaster/metabolismo , Masculino , Proteínas Nucleares/química , Proteínas Nucleares/genética , Factores de Transcripción/química , Factores de Transcripción/genética
8.
Proc Natl Acad Sci U S A ; 110(52): E5049-58, 2013 Dec 24.
Artículo en Inglés | MEDLINE | ID: mdl-24324176

RESUMEN

Directional transport of mRNA is a universal feature in eukaryotes, requiring the assembly of motor-dependent RNA-transport particles. The cytoplasmic transport of mRNAs is preceded by the nuclear assembly of pre-messenger ribonucleoprotein particles (mRNPs). In budding yeast, the asymmetric synthesis of HO 1 (ASH1) pre-mRNP originates already cotranscriptionally and passes through the nucleolus before its nuclear export. The nucleolar localization of ASH1 mRNA protein 1 (Loc1p) is required for efficient ASH1 mRNA localization. Immunoprecipitation experiments have revealed that Loc1p forms cocomplexes with other components of the ASH1 transport complex. However, it remains unclear how Loc1p is recruited into this mRNP and why Loc1p is important for ASH1 mRNA localization. Here we demonstrate that Loc1p undergoes a direct and specific interaction with the ASH1 mRNA-binding Swi5p-dependent HO expression protein 2 (She2p). This cocomplex shows higher affinity and specificity for RNA bearing localization elements than the individual proteins. It also stabilizes the otherwise transient binding of She2p to ASH1 mRNA, suggesting that cooperative mRNA binding of Loc1p with She2p is the required nuclear function of Loc1p for ASH1 mRNA localization. After nuclear export, myosin-bound She3p joins the ASH1 mRNP to form a highly specific cocomplex with She2p and ASH1 mRNA. Because Loc1p is found only in the nucleus, it must be removed from the complex directly before or after export. In vitro and in vivo experiments indicate that the synergistic interaction of She2p and She3p displaces Loc1p from the ASH1 complex, allowing free Loc1p to rapidly reenter the nucle(ol)us. Together these findings suggest an ordered process of nuclear assembly and reorganization for the maturation of localizing ASH1 mRNPs.


Asunto(s)
Proteínas Nucleares/metabolismo , Transporte de ARN/fisiología , Proteínas de Unión al ARN/metabolismo , Proteínas Represoras/metabolismo , Ribonucleoproteínas/biosíntesis , Proteínas de Saccharomyces cerevisiae/metabolismo , Ensayo de Cambio de Movilidad Electroforética , Escherichia coli , Proteínas Luminiscentes , Ribonucleoproteínas/metabolismo , Saccharomycetales , Proteína Fluorescente Roja
9.
PLoS Biol ; 9(4): e1000611, 2011 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-21526221

RESUMEN

In eukaryotes, hundreds of mRNAs are localized by specialized transport complexes. For localization, transcripts are recognized by RNA-binding proteins and incorporated into motor-containing messenger ribonucleoprotein particles (mRNPs). To date, the molecular assembly of such mRNPs is not well understood and most details on cargo specificity remain unresolved. We used ASH1-mRNA transport in yeast to provide a first assessment of where and how localizing mRNAs are specifically recognized and incorporated into mRNPs. By using in vitro-interaction and reconstitution assays, we found that none of the implicated mRNA-binding proteins showed highly specific cargo binding. Instead, we identified the cytoplasmic myosin adapter She3p as additional RNA-binding protein. We further found that only the complex of the RNA-binding proteins She2p and She3p achieves synergistic cargo binding, with an at least 60-fold higher affinity for localizing mRNAs when compared to control RNA. Mutational studies identified a C-terminal RNA-binding fragment of She3p to be important for synergistic RNA binding with She2p. The observed cargo specificity of the ternary complex is considerably higher than previously reported for localizing mRNAs. It suggests that RNA binding for mRNP localization generally exhibits higher selectivity than inferred from previous in vitro data. This conclusion is fully consistent with a large body of in vivo evidence from different organisms. Since the ternary yeast complex only assembles in the cytoplasm, specific mRNA recognition might be limited to the very last steps of mRNP assembly. Remarkably, the mRNA itself triggers the assembly of mature, motor-containing complexes. Our reconstitution of a major portion of the mRNA-transport complex offers new and unexpected insights into the molecular assembly of specific, localization-competent mRNPs and provides an important step forward in our mechanistic understanding of mRNA localization in general.


Asunto(s)
Citoplasma/metabolismo , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/metabolismo , Ribonucleoproteínas/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Secuencia de Aminoácidos , Núcleo Celular/metabolismo , Secuencias Invertidas Repetidas , Datos de Secuencia Molecular , Mutagénesis Sitio-Dirigida , Conformación de Ácido Nucleico , Unión Proteica , Estructura Secundaria de Proteína , Estructura Terciaria de Proteína , Transporte de Proteínas , Transporte de ARN , Proteínas de Unión al ARN/genética , Proteínas Represoras/genética , Proteínas Represoras/metabolismo , Proteínas de Saccharomyces cerevisiae/genética
10.
RNA ; 15(11): 2002-12, 2009 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-19710186

RESUMEN

In eukaryotic cells, dozens to hundreds of different mRNAs are localized by specialized motor-dependent transport complexes. One of the best-studied examples for directional mRNA transport is the localization of ASH1 mRNA in Saccharomyces cerevisiae. For transport, ASH1 mRNA is bound by the unusual RNA-binding protein She2p. Although previous results indicated that She2p forms dimers required for RNA binding and transcript localization, it remained unclear if the dimer constitutes the minimal RNA-binding unit assembling in vivo. By using analytical ultracentrifugation we found that She2p forms larger oligomeric complexes in solution. We also identified a point mutant that shows impaired oligomer formation. Size-exclusion chromatography suggests that She2p forms defined tetramers at physiological concentrations. Subsequent structural studies by small-angle X-ray scattering confirmed this finding and demonstrated that the previously observed She2p dimers interact in a head-to-head conformation to form an elongated tetrameric complex. This She2p tetramer suggests the generation of large continuous RNA-binding surfaces at both sides of the complex. Biochemical studies and immunostaining of cells confirmed that She2p tetramer formation is required for RNA binding, efficient mRNP assembly, and mRNA localization in vivo. Our finding on She2p tetramerization resolves previously raised questions on complex formation and mRNP function.


Asunto(s)
Multimerización de Proteína , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/metabolismo , Ribonucleoproteínas/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Cristalografía por Rayos X , Modelos Moleculares , Mutación , Unión Proteica , Estructura Cuaternaria de Proteína , Proteínas de Unión al ARN/genética , Proteínas de Saccharomyces cerevisiae/genética , Ultracentrifugación
11.
Bio Protoc ; 11(5): e3946, 2021 Mar 05.
Artículo en Inglés | MEDLINE | ID: mdl-33796620

RESUMEN

RNA-protein interactions are often mediated by dedicated canonical RNA binding domains. However, interactions through non-canonical domains with unknown specificity are increasingly observed, raising the question how RNA targets are recognized. Knowledge of the intrinsic RNA binding specificity contributes to the understanding of target selectivity and function of an individual protein. The presented in vitro RNA immunoprecipitation assay (vitRIP) uncovers intrinsic RNA binding specificities of isolated proteins using the total cellular RNA pool as a library. Total RNA extracted from cells or tissues is incubated with purified recombinant proteins, RNA-protein complexes are immunoprecipitated and bound transcripts are identified by deep sequencing or quantitative RT-PCR. Enriched RNA classes and the nucleotide frequency in these RNAs inform on the intrinsic specificity of the recombinant protein. The simple and versatile protocol can be adapted to other RNA binding proteins and total RNA libraries from any cell type or tissue. Graphic abstract: Figure 1. Schematic of the in vitro RNA immunoprecipitation (vitRIP) protocol.

12.
EMBO Rep ; 9(8): 781-7, 2008 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-18566598

RESUMEN

Cytoplasmic localization and localized translation of messenger RNAs contribute to asymmetrical protein distribution. Recognition of localized mRNAs by RNA-binding proteins can occur in the cytoplasm or, alternatively, co- or post-transcriptionally in the nucleus. In budding yeast, mRNAs destined for localization are bound by the She2 protein before their nuclear export. Here, we show that a specific transcript, known as ASH1 mRNA, and She2 localize specifically to the nucleolus when their nuclear export is blocked. Nucleolar She2 localization is enhanced in a She2 mutant that cannot bind to RNA. A fusion protein of the amino terminus of She3 and She2 (She3N-She2) fails to enter the nucleus, but does not impair ASH1 mRNA localization. Instead, these cells fail to distribute Ash1 protein asymmetrically, which is caused by a defective translational control of ASH1 mRNA. Our results indicate that the nucleolar transit of RNA-binding proteins such as She2 is necessary for the correct assembly of translationally silenced localizing messenger ribonucleoproteins.


Asunto(s)
Proteínas de Unión al ADN/metabolismo , Biosíntesis de Proteínas , ARN Mensajero/metabolismo , Proteínas de Unión al ARN/metabolismo , Proteínas Represoras/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Transporte Biológico , Núcleo Celular/metabolismo , Citoplasma/metabolismo , Proteínas de Unión al ADN/genética , Inmunoprecipitación , Microscopía Fluorescente , ARN Mensajero/genética , Proteínas de Unión al ARN/genética , Proteínas Represoras/genética , Ribonucleoproteínas , Proteínas de Saccharomyces cerevisiae/genética , Temperatura
13.
Proc Natl Acad Sci U S A ; 104(50): 19778-83, 2007 Dec 11.
Artículo en Inglés | MEDLINE | ID: mdl-18056806

RESUMEN

Myosin-motors are conserved from yeast to human and transport a great variety of cargoes. Most plus-end directed myosins, which constitute the vast majority of all myosin motors, form stable dimers and interact constitutively with their cargo complexes. To date, little is known about regulatory mechanisms for cargo-complex assembly. In this study, we show that the type V myosin Myo4p binds to its cargo via two distinct binding regions, the C-terminal tail and a coiled-coil domain-containing fragment. Furthermore, we find that Myo4p is strictly monomeric at physiologic concentrations. Because type V myosins are thought to require dimerization for processive movement, a mechanism must be in place to ensure that oligomeric Myo4p is incorporated into cargo-translocation complexes. Indeed, we find that artificial dimerization of the Myo4p C-terminal tail promotes stabilization of myosin-cargo complexes, suggesting that full-length Myo4p dimerizes in the cocomplex as well. We also combined the Myo4p C-terminal tail with the coiled-coil region, lever arm, and motor domain from a different myosin to form constitutively dimeric motor proteins. This heterologous motor successfully translocates its cargo in vivo, suggesting that wild-type Myo4p may also function as a dimer during cargo-complex transport.


Asunto(s)
Miosina Tipo V/metabolismo , Dimerización , Cadenas Pesadas de Miosina/genética , Cadenas Pesadas de Miosina/metabolismo , Miosina Tipo V/química , Miosina Tipo V/genética , Unión Proteica , Estructura Secundaria de Proteína , Transporte de Proteínas , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo
14.
J Psychosom Res ; 63(6): 647-55, 2007 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-18061756

RESUMEN

OBJECTIVE: Treatment of breast cancer is usually associated with significant psychological stress. In this study, we examined the effects of relaxation and visualization therapy (RVT) on psychological distress, cortisol levels, and immunological parameters of breast cancer patients undergoing radiotherapy. METHODS: Participants were randomly assigned to either the experimental (n=20) who underwent group RVT for 24 consecutive days or control group (n=14) who were on radiotherapy only. Psychological scores (stress, anxiety, and depression) were measured by structured clinical interviews. Salivary cortisol was assessed along the day. Lymphocytes were isolated and cultured to measure T-cell proliferation and sensitivity to glucocorticoids (GCs). RESULTS: RVT was effective to reduce stress, anxiety, and depression scores (all P<.05). However, cortisol levels as well as proliferation remained unchanged following RVT. Although T cells of experimental group were more sensitive to GCs than cells of controls at baseline, no changes were noted following RVT. Cortisol levels were positively correlated to anxiety and depression scores and inversely correlated to T-cell proliferation and sensitivity to GCs. CONCLUSION: We conclude that the psychological intervention was capable to attenuate the emotional distress presented during radiotherapy treatment. A longer RVT or worse psychological morbidity at baseline may be necessary to translate psychological into biological changes.


Asunto(s)
Trastornos de Ansiedad/etiología , Trastornos de Ansiedad/terapia , Neoplasias de la Mama/psicología , Neoplasias de la Mama/radioterapia , Trastorno Depresivo Mayor/etiología , Trastorno Depresivo Mayor/terapia , Imágenes en Psicoterapia , Neuroinmunomodulación , Terapia por Relajación , Adulto , Anciano , Antiinflamatorios/uso terapéutico , Trastornos de Ansiedad/diagnóstico , Neoplasias de la Mama/tratamiento farmacológico , Femenino , Humanos , Hidrocortisona/análisis , Persona de Mediana Edad , Saliva/química , Linfocitos T/fisiología , Factores de Tiempo , Insuficiencia del Tratamiento
15.
Biochimie ; 94(7): 1490-8, 2012 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-22239950

RESUMEN

A large part of higher eukaryotic genomes is transcribed into RNAs lacking any significant open reading frame. This "non-coding part" has been shown to actively contribute to regulating gene expression, but the mechanisms are largely unknown. Particularly instructive examples are provided by the dosage compensation systems, which assure that the single X chromosome in male cells and the two X chromosomes in female cells give rise to similar amounts of gene product. Although this is achieved by very different strategies in mammals and fruit flies, long, non-coding RNAs (lncRNAs) are involved in both cases. Here we summarize recent progress towards unraveling the mechanisms, by which the Xist and roX RNAs mediate the selective association of regulators with individual target chromosomes, to initiate dosage compensation in mammals and fruit flies, respectively.


Asunto(s)
Cromosomas/genética , Compensación de Dosificación (Genética)/genética , Regulación de la Expresión Génica/genética , ARN no Traducido/química , ARN no Traducido/genética , Transcripción Genética/genética , Animales , Drosophila melanogaster/genética , Humanos
16.
J Psychosom Res ; 72(4): 282-7, 2012 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-22405222

RESUMEN

OBJECTIVE: To investigate psychological stress on the prognosis of the postoperative recurrence of keloids. METHODS: Patients with keloids (n=25), candidates for surgical resection and postoperative radiotherapy, had their psychological stress evaluated on the day before the surgical procedure. The parameters evaluated were pain and itching (Visual Numerical Scale), quality of life (Questionnaire QualiFibro/Cirurgia Plástica-UNIFESP), perceived stress (Perceived Stress Scale), depression and anxiety (Hospital Depression and Anxiety Scale), salivary cortisol and minimum and maximum galvanic skin responses (GSR) at rest and under stress (i.e., while the questionnaires were being filled out). Patients were evaluated during the 3rd, 6th, 9th and 12th months of postoperative care. During each return visit, two experts classified the lesions as non-recurrent and recurrent. RESULTS: The recurrence group presented the greatest values in GSR during a stressful situation. The chance of recurrence increased by 34% at each increase of 1000 arbitrary units in maximum GSR during stress. CONCLUSION: Psychological stress influenced the recurrence of keloids.


Asunto(s)
Queloide/psicología , Queloide/cirugía , Complicaciones Posoperatorias/psicología , Estrés Psicológico/complicaciones , Adulto , Trastornos de Ansiedad/diagnóstico , Trastornos de Ansiedad/psicología , Nivel de Alerta/fisiología , Trastorno Depresivo/diagnóstico , Trastorno Depresivo/psicología , Femenino , Estudios de Seguimiento , Respuesta Galvánica de la Piel/fisiología , Humanos , Hidrocortisona/sangre , Masculino , Dimensión del Dolor , Inventario de Personalidad/estadística & datos numéricos , Pronóstico , Psicometría , Calidad de Vida/psicología , Recurrencia , Factores de Riesgo , Saliva/química , Adulto Joven
17.
An Bras Dermatol ; 84(2): 143-50, 2009.
Artículo en Inglés, Portugués | MEDLINE | ID: mdl-19503982

RESUMEN

BACKGROUND: The visible aspect of skin lesions and its psychological impact interfere in the quality of life of patients. OBJECTIVES: To assess the quality of life and site of dermatological lesion; to check associations between variables and compare levels of quality of life in patients with lesions on the face and/or hands and patients with lesions in parts of the body other than face and/or hands. METHODS: descriptive, association-based cross-sectional study. Two hundred and five subjects were assessed using SF-36 Generic Life Quality Questionnaire "The Medical Outcomes Study 36-item Short-Form Health Survey" (SF-36); the Dermatology Life Quality Index DLQI-BRA, and socio-demographical and lesion site data files. RESULTS: No significant differences were observed in the results for quality of life between the two groups but the number of associations between SF-36 and DLQI-BRA was higher in the group with lesions on the face and/or hands. Significant differences were verified in a further detailed division into five groups. The significant difference (p=0.05) appeared between the group with lesions on the face and/or hands and the group with generalized lesions, being that the latter presented an average ranking of 114.06 compared with 69.1935 in the former group. CONCLUSION: Regardless of the site of lesion, the feeling of exposure and the damages to which the dermatological patients are exposed are similar. It seems that skin diseases bring about the feeling of exposure and embarrassment no matter which site of the body is affected because in any intimate approach there is some sort of exposure involved.


Asunto(s)
Encuestas Epidemiológicas , Calidad de Vida/psicología , Enfermedades de la Piel/patología , Enfermedades de la Piel/psicología , Adulto , Anciano , Anciano de 80 o más Años , Estudios Transversales , Dermatitis Atópica/patología , Dermatitis Atópica/psicología , Femenino , Humanos , Queratosis/patología , Queratosis/psicología , Masculino , Persona de Mediana Edad , Psoriasis/patología , Psoriasis/psicología , Índice de Severidad de la Enfermedad , Estadísticas no Paramétricas , Encuestas y Cuestionarios , Adulto Joven
18.
Mol Microbiol ; 61(5): 1237-51, 2006 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-16925557

RESUMEN

Members of the soil-dwelling, sporulating prokaryotic genus Streptomyces are indispensable for the recycling of the most abundant polysaccharides on earth (cellulose and chitin), and produce a wide range of antibiotics and industrial enzymes. How do these organisms sense the nutritional state of the environment, and what controls the signal for the switch to antibiotic production and morphological development? Here we show that high extracellular concentrations of N-acetylglucosamine, the monomer of chitin, prevent Streptomyces coelicolor progressing beyond the vegetative state, and that this effect is absent in a mutant defective of N-acetylglucosamine transport. We provide evidence that the signal is transmitted through the GntR-family regulator DasR, which controls the N-acetylglucosamine regulon, including the pts genes ptsH, ptsI and crr needed for uptake of N-acetylglucosamine. Deletion of dasR or the pts genes resulted in a bald phenotype. Binding of DasR to its target genes is abolished by glucosamine 6-phosphate, a central molecule in N-acetylglucosamine metabolism. Extracellular complementation experiments with many bld mutants showed that the dasR mutant is arrested at an early stage of the developmental programme, and does not fit in the previously described bld signalling cascade. Thus, for the first time we are able to directly link carbon (and nitrogen) metabolism to development, highlighting a novel type of metabolic regulator, which senses the nutritional state of the habitat, maintaining vegetative growth until changing circumstances trigger the switch to sporulation. Our work, and the model it suggests, provide new leads towards understanding how microorganisms time developmental commitment.


Asunto(s)
Acetilglucosamina/metabolismo , Proteínas Bacterianas/metabolismo , Fosfotransferasas/metabolismo , Streptomyces coelicolor/metabolismo , Proteínas Bacterianas/genética , Regulación Bacteriana de la Expresión Génica/genética , Prueba de Complementación Genética , Glucosamina/análogos & derivados , Glucosamina/farmacología , Glucosa-6-Fosfato/análogos & derivados , Glucosa-6-Fosfato/farmacología , Microscopía Electrónica de Rastreo/métodos , Modelos Biológicos , Mutación/genética , Fenotipo , Fosfotransferasas/genética , Unión Proteica/efectos de los fármacos , Regulón/genética , Streptomyces coelicolor/genética , Streptomyces coelicolor/ultraestructura , Especificidad por Sustrato
19.
Cell ; 121(3): 363-73, 2005 May 06.
Artículo en Inglés | MEDLINE | ID: mdl-15882619

RESUMEN

SWI2/SNF2 ATPases remodel chromatin or other DNA:protein complexes by a poorly understood mechanism that involves ATP-dependent DNA translocation and generation of superhelical torsion. Crystal structures of a dsDNA-translocating SWI2/SNF2 ATPase core from Sulfolobus solfataricus reveal two helical SWI2/SNF2 specific subdomains, fused to a DExx box helicase-related ATPase core. Fully base paired duplex DNA binds along a central cleft via both minor groove strands, indicating that SWI2/SNF2 ATPases travel along the dsDNA minor groove without strand separation. A structural switch, linking DNA binding and the active site DExx motif, may account for the stimulation of ATPase activity by dsDNA. Our results suggest that torque in remodeling processes is generated by an ATP-driven screw motion of DNA along the active site cleft. The structures also redefine SWI2/SNF2 functional motifs and uncover unexpected structural correlation of mutations in Cockayne and X-linked mental retardation syndromes.


Asunto(s)
Cristalografía por Rayos X , Proteínas de Unión al ADN/química , ADN/química , Sulfolobus solfataricus/enzimología , Factores de Transcripción/química , Adenosina Trifosfatasas/química , Adenosina Trifosfatasas/metabolismo , Adenosina Trifosfato/metabolismo , Secuencias de Aminoácidos/genética , Secuencia de Aminoácidos , Sustitución de Aminoácidos/genética , Sitios de Unión , Catálisis , Dominio Catalítico , Ensamble y Desensamble de Cromatina/genética , ADN/metabolismo , ADN Helicasas/química , ADN Helicasas/genética , ADN Helicasas/metabolismo , Proteínas de Unión al ADN/genética , Proteínas de Unión al ADN/metabolismo , Cinética , Modelos Moleculares , Datos de Secuencia Molecular , Conformación de Ácido Nucleico , Oligonucleótidos/química , Oligonucleótidos/genética , Oligonucleótidos/metabolismo , Poli T/metabolismo , Polidesoxirribonucleótidos/metabolismo , Unión Proteica , Conformación Proteica , Homología de Secuencia de Aminoácido , Sulfolobus solfataricus/genética , Factores de Transcripción/genética , Factores de Transcripción/metabolismo
20.
An. bras. dermatol ; 84(2): 143-150, mar.-abr. 2009. tab
Artículo en Inglés, Portugués | LILACS | ID: lil-515917

RESUMEN

FUNDAMENTOS - O aspecto visível das lesões de pele e seu impacto psicológico interferem na qualidade de vida dos pacientes. OBJETIVOS - Avaliar qualidade de vida e localização da lesão dermatológica, verificar associação entre variáveis e comparar níveis de qualidade de vida em pacientes com lesões na face/ou mãos e pacientes somente com lesões em outras regiões do corpo que não face e/ou mãos. MÉTODO - Estudo transversal, descritivo, de ssociação. Foram avaliados 205 sujeitos através do Questionário Genérico de Qualidade de Vida- SF-36 "The Medical Outcomes Study 36-item Short-Form Health Survey" (SF-36) e do Dermatology Life quality Index, fichas de dados sócio-demográficos e de localização da lesão. RESULTADOS - Não foram observadas diferenças significativas na qualidade de vida entre os dois grupos, mas o número de associações entre SF-36 e DLQI-BRA foi superior no grupo com lesões em face e/ou mãos. Diferenças significativas foram verificadas quando da divisão em cinco grupos. A diferença significativa (p=0,05) foi entre o grupo com lesões somente em face e/ou mãos e o grupo com lesões generalizadas, sendo que este último teve posto médio de 114,06 contra 69,1935 do outro grupo. CONCLUSÕES - Independente da localização da lesão, o sentimento de exposição e os prejuízos a que fica sujeito o paciente dermatológico são semelhantes. As doenças da pele, ao que parece, provocam sentimento de exposição e constrangimento, independente do local do corpo acometido, pois na aproximação mais íntima de outra pessoa está implicada certa exposição.


BACKGROUND - The visible aspect of skin lesions and its psychological impact interfere in the quality of life of patients. OBJECTIVES- To assess the quality of life and site of dermatological lesion; to check associations between variables and compare levels of quality of life in patients with lesions on the face and/or hands and patients with lesions in parts of the body other than face and/or hands. METHODS - descriptive, association-based cross-sectional study. Two hundred and five subjects were assessed using SF-36 Generic Life Quality Questionnaire "The Medical Outcomes Study 36-item Short-Form Health Survey" (SF-36); the Dermatology Life Quality Index DLQI-BRA, and socio-demographical and lesion site data files. RESULTS - No significant differences were observed in the results for quality of life between the two groups but the number of associations between SF-36 and DLQI-BRA was higher in the group with lesions on the face and/or hands. Significant differences were verified in a further detailed division into five groups. The significant difference (p=0.05) appeared between the group with lesions on the face and/or hands and the group with generalized lesions, being that the latter presented an average ranking of 114.06 compared with 69.1935 in the former group. CONCLUSION - Regardless of the site of lesion, the feeling of exposure and the damages to which the dermatological patients are exposed are similar. It seems that skin diseases bring about the feeling of exposure and embarrassment no matter which site of the body is affected because in any intimate approach there is some sort of exposure involved.


Asunto(s)
Adulto , Anciano , Anciano de 80 o más Años , Femenino , Humanos , Masculino , Persona de Mediana Edad , Adulto Joven , Encuestas Epidemiológicas , Calidad de Vida/psicología , Enfermedades de la Piel/patología , Enfermedades de la Piel/psicología , Estudios Transversales , Dermatitis Atópica/patología , Dermatitis Atópica/psicología , Queratosis/patología , Queratosis/psicología , Psoriasis/patología , Psoriasis/psicología , Índice de Severidad de la Enfermedad , Estadísticas no Paramétricas , Encuestas y Cuestionarios , Adulto Joven
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