RESUMO
Psychedelic indolethylamines have emerged as potential medicines to treat several psychiatric pathologies. Natural sources of these compounds include 'magic mushrooms' (Psilocybe spp.), plants used to prepare ayahuasca, and toads. The skin and parotid glands of certain toads accumulate a variety of specialized metabolites including toxic guanidine alkaloids, lipophilic alkaloids, poisonous steroids, and hallucinogenic indolethylamines such as DMT, 5-methoxy-DMT, and bufotenin. The occurrence of psychedelics has contributed to the ceremonial use of toads, particularly among Mesoamerican peoples. Yet, the biosynthesis of psychedelic alkaloids has not been elucidated. Herein, we report a novel indolethylamine N-methyltransferase (RmNMT) from cane toad (Rhinella marina). The RmNMT sequence was used to identify a related NMT from the common toad, Bufo bufo. Close homologs from various frog species were inactive, suggesting a role for psychedelic indolethylamine biosynthesis in toads. Enzyme kinetic analyses and comparison with functionally similar enzymes showed that recombinant RmNMT was an effective catalyst and not product inhibited. The substrate promiscuity of RmNMT enabled the bioproduction of a variety of substituted indolethylamines at levels sufficient for purification, pharmacological screening, and metabolic stability assays. Since the therapeutic potential of psychedelics has been linked to activity at serotonergic receptors, we evaluated binding of derivatives at 5-HT1A and 5-HT2A receptors. Primary amines exhibited enhanced affinity at the 5-HT1A receptor compared with tertiary amines. With the exception of 6-substituted derivatives, N,N-dimethylation also protected against catabolism by liver microsomes.
RESUMO
Cardiac fibrosis is observed across diverse etiologies of heart failure. Granzyme B (GzmB) is a serine protease involved in cell-mediated cytotoxicity in conjunction with the pore-forming protein, perforin. Recent evidence suggests that GzmB also contributes to matrix remodeling and fibrosis through an extracellular, perforin-independent process. However, the role of GzmB in the onset and progression of cardiac fibrosis remains elusive. The present study investigated the role of GzmB in the pathogenesis of cardiac fibrosis. GzmB was elevated in fibrotic human hearts and in angiotensin II-induced murine cardiac fibrosis. Genetic deficiency of GzmB reduced angiotensin II-induced cardiac hypertrophy and fibrosis, independently of perforin. GzmB deficiency also reduced microhemorrhage, inflammation, and fibroblast accumulation in vivo. In vitro, GzmB cleaved the endothelial junction protein, vascular endothelial (VE)-cadherin, resulting in the disruption of endothelial barrier function. Together, these results suggest a perforin-independent, extracellular role for GzmB in the pathogenesis of cardiac fibrosis.
Assuntos
Granzimas/metabolismo , Cardiopatias/enzimologia , Cardiopatias/patologia , Adulto , Idoso , Animais , Modelos Animais de Doenças , Feminino , Fibrose/enzimologia , Fibrose/patologia , Imunofluorescência , Humanos , Imuno-Histoquímica , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Pessoa de Meia-Idade , Reação em Cadeia da Polimerase em Tempo Real , Adulto JovemRESUMO
Chronic non-healing wounds including diabetic, venous, and decubitus skin ulcers are currently lacking effective therapies. Non-healing diabetic ulcers can lead to amputations as progress into a highly chronic state before detection and existing treatments for these wounds often fail. Granzyme B (GzmB) is a serine protease that was, until recently, believed to function exclusively in cytotoxic lymphocyte-mediated apoptosis. However, during excessive or chronic inflammation, GzmB can accumulate in the extracellular milieu, retain its activity, and cleave a number of important extracellular proteins. Epidermal growth factor receptor (EGFR) is a transmembrane receptor involved in cellular processes such as proliferation and migration. EGFR signaling is integral to the wound healing process. The present study investigated the effects of GzmB on keratinocyte cell migration using HaCaT cell line. Using electric cell-substrate impedance sensing and scratch assays, the present study demonstrates that GzmB inhibits keratinocyte migration by interfering with the EGFR pathway. GzmB limited cell transition into a migratory morphology and was found to reduce ligand-induced EGFR phosphorylation. Inhibition of GzmB reversed the aforementioned effects. In summary, data from the present study suggest key role for GzmB in the pathogenesis of impaired wound healing through the impairment of EGFR signaling and cell migration.
Assuntos
Movimento Celular/efeitos dos fármacos , Receptores ErbB/metabolismo , Granzimas/farmacologia , Queratinócitos/citologia , Queratinócitos/efeitos dos fármacos , Transdução de Sinais/efeitos dos fármacos , Linhagem Celular , Humanos , Queratinócitos/metabolismo , Fosforilação/efeitos dos fármacos , Cicatrização/efeitos dos fármacosRESUMO
The psychedelic prodrug psilocybin has shown therapeutic benefits for the treatment of numerous psychiatric conditions. Despite positive clinical end points targeting depression and anxiety, concerns regarding the duration of the psychedelic experience produced by psilocybin, associated with enduring systemic exposure to the active metabolite psilocin, pose a barrier to its therapeutic application. Our objective was to create a novel prodrug of psilocin with similar therapeutic benefits but a reduced duration of psychedelic effects compared with psilocybin. Here, we report the synthesis and functional screening of 28 new chemical entities. Our strategy was to introduce a diversity of cleavable groups at the 4-hydroxy position of the core indole moiety to modulate metabolic processing. We identified several novel prodrugs of psilocin with altered pharmacokinetic profiles and reduced pharmacological exposure compared with psilocybin. These candidate prodrugs have the potential to maintain the long-term benefits of psilocybin therapy while attenuating the duration of psychedelic effects.
Assuntos
Alucinógenos , Pró-Fármacos , Humanos , Psilocibina/farmacologia , Psilocibina/uso terapêutico , Alucinógenos/farmacologia , Alucinógenos/uso terapêutico , Pró-Fármacos/farmacologia , Pró-Fármacos/uso terapêutico , Transtornos de Ansiedade/tratamento farmacológicoRESUMO
In response to nutrient starvation, the budding yeast Saccharomyces cerevisiae abandons mitotic proliferation and embarks on a differentiation process that leads through meiosis to the formation of haploid spores. This process is driven by cascading waves of meiosis-specific-gene expression. The early meiosis-specific genes are repressed during mitotic proliferation by the DNA-binding protein Ume6 in combination with repressors Rpd3 and Sin3. The expression of meiosis-specific transcription factor Ime1 leads to activation of the early meiosis-specific genes. We investigated the stability and promoter occupancy of Ume6 in sporulating cells and determined that it remains bound to early meiosis-specific gene promoters when those genes are activated. Furthermore, we find that the repressor Rpd3 remains associated with Ume6 after the transactivator Ime1 has joined the complex and that the Gcn5 and Tra1 components of the SAGA complex bind to the promoter of IME2 in an Ime1-dependent fashion to induce transcription of the early meiosis-specific genes. Our investigation supports a model whereby Ume6 provides a platform allowing recruitment of both activating and repressing factors to coordinate the expression of the early meiosis-specific genes in Saccharomyces cerevisiae.
Assuntos
Regulação Fúngica da Expressão Gênica/fisiologia , Meiose/fisiologia , Proteínas Serina-Treonina Quinases/metabolismo , Proteínas Repressoras/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Proteínas de Ligação a DNA/metabolismo , Histona Desacetilases/metabolismo , Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição/metabolismoRESUMO
The B-type cyclins Clb5 and Clb6 are essential activators of DNA replication during sporulation in Saccharomyces cerevisiae. The expression of CLB5 is maximally induced during the middle phase of sporulation by the transcription factor Ndt80. We have performed an analysis of the CLB5 promoter and have identified two middle sporulation elements (MSEs) that act as binding sites for Ndt80. Although both MSE sequences bind Ndt80 in vitro, they display differential effectiveness in their ability to function as cis-acting regulatory sequences in vivo. Mutation of both MSE sequences in the CLB5 promoter profoundly reduces the induction of CLB5 transcription during the middle phase of sporulation but results in no obvious defect in progression through meiosis and sporulation, implying that the Ndt80-dependent induction of CLB5 is not required for effective DNA replication or chromosome division.
Assuntos
Ciclina B/genética , Regulação Fúngica da Expressão Gênica , Regiões Promotoras Genéticas , Elementos de Resposta , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Esporos Fúngicos/genética , Sequência de Bases , Sequência Conservada , Ciclina B/metabolismo , Proteínas de Ligação a DNA/isolamento & purificação , Proteínas de Ligação a DNA/metabolismo , Ensaio de Desvio de Mobilidade Eletroforética , Genes Reporter , Mutagênese Sítio-Dirigida , Saccharomyces cerevisiae/crescimento & desenvolvimento , Proteínas de Saccharomyces cerevisiae/isolamento & purificação , Proteínas de Saccharomyces cerevisiae/metabolismo , Alinhamento de Sequência , Esporos Fúngicos/crescimento & desenvolvimento , Fatores de Transcrição/isolamento & purificação , Fatores de Transcrição/metabolismo , Transcrição Gênica , Ativação TranscricionalRESUMO
Granzyme B (GzmB) is a serine protease that has long been thought to function exclusively in lymphocyte-mediated apoptosis. In recent years, this paradigm has been revisited due to the recognition that GzmB accumulates in the extracellular milieu in many autoimmune and chronic inflammatory disorders, and contributes to impaired tissue remodeling due to the cleavage of extracellular matrix proteins. Knockout studies suggest that GzmB-mediated cleavage of decorin (DCN) contributes to impaired collagen fibrillogenesis and remodeling. As DCN is anti-fibrotic and contributes to reduced hypertrophic scarring, GzmB-induced DCN cleavage could play a role in wound healing following burn injury. In the present study, a novel, gel-formulated, first-in-class small-molecule inhibitor of GzmB, VTI-1002, was assessed in a murine model of impaired, diabetic burn wound healing. VTI-1002 exhibited high specificity, potency, and target selectivity. Gel-formulated VTI-1002 was able to penetrate the stratum corneum and was retained in the skin with minimal systemic absorption. Daily topical administration of VTI-1002 gel for 30 days following thermal injury showed significantly accelerated wound closure, increased DCN protein levels, and collagen organization that was translated into significantly increased wound tensile strength compared to controls. Overall, VTI-1002 gel was well-tolerated in vivo and no adverse events were observed. Topical application of VTI-1002 represents a novel therapeutic approach for the treatment of cutaneous burn wounds.
Assuntos
Queimaduras/patologia , Granzimas/antagonistas & inibidores , Bibliotecas de Moléculas Pequenas/administração & dosagem , Bibliotecas de Moléculas Pequenas/farmacologia , Cicatrização/efeitos dos fármacos , Administração Tópica , Animais , Cicatriz/patologia , Diabetes Mellitus Experimental/patologia , Modelos Animais de Doenças , Granzimas/metabolismo , Masculino , Camundongos Endogâmicos C57BLRESUMO
The Saccharomyces cerevisiae meiosis-specific transcription factor Ndt80 is responsible for the induction of a class of genes referred to as middle sporulation genes. Among the members of this family are the B-type cyclins and other genes whose products are required for meiotic chromosome division and spore morphogenesis. Inactivation of NDT80 leads to a failure to induce the middle sporulation genes and a subsequent arrest in pachytene. The expression of NDT80 is itself highly regulated. The initial transcription of NDT80 is dependent upon the protein kinase Ime2; once Ndt80 protein accumulates, it activates its own promoter, thus generating an autoactivation loop. In addition to being transcriptionally regulated, Ndt80 protein is posttranslationally regulated. Phosphorylation of Ndt80 occurs coincident with its activation as a transcription factor. If expressed prematurely in meiosis, Ndt80 accumulates initially in an unmodified form that is subsequently modified by phosphorylation. In contrast, Ndt80 expressed in ime2 mutant strains does not become modified and has a reduced ability to activate transcription of its target genes. Ime2 can also phosphorylate Ndt80 in vitro, further supporting a direct role for Ime2 in the phosphorylation of Ndt80. These data indicate that Ime2 plays a novel and previously unexpected role in promoting chromosome dissemination and progress through meiotic development by activating Ndt80.
Assuntos
Proteínas de Ciclo Celular , Proteínas de Ligação a DNA/metabolismo , Proteínas Fúngicas/metabolismo , Regulação Fúngica da Expressão Gênica , Meiose/fisiologia , Proteínas Quinases/metabolismo , Proteínas de Saccharomyces cerevisiae , Fatores de Transcrição/metabolismo , Transporte Ativo do Núcleo Celular , Sítios de Ligação , Núcleo Celular/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas Fúngicas/genética , Genes Fúngicos , Peptídeos e Proteínas de Sinalização Intracelular , Fosforilação , Regiões Promotoras Genéticas , Proteínas Quinases/genética , Proteínas Serina-Treonina Quinases , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismo , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/fisiologia , Esporos Fúngicos/fisiologia , Especificidade por Substrato , Fatores de Transcrição/genética , Ativação TranscricionalRESUMO
The initiation of DNA replication in Saccharomyces cerevisiae depends upon the destruction of the Clb-Cdc28 inhibitor Sic1. In proliferating cells Cln-Cdc28 complexes phosphorylate Sic1, which stimulates binding of Sic1 to SCF(Cdc4) and triggers its proteosome mediated destruction. During sporulation cyclins are not expressed, yet Sic1 is still destroyed at the G1-/S-phase boundary. The Cdk (cyclin dependent kinase) sites are also required for Sic1 destruction during sporulation. Sic1 that is devoid of Cdk phosphorylation sites displays increased stability and decreased phosphorylation in vivo. In addition, we found that Sic1 was modified by ubiquitin in sporulating cells and that SCF(Cdc4) was required for this modification. The meiosis-specific kinase Ime2 has been proposed to promote Sic1 destruction by phosphorylating Sic1 in sporulating cells. We found that Ime2 phosphorylates Sic1 at multiple sites in vitro. However, only a subset of these sites corresponds to Cdk sites. The identification of multiple sites phosphorylated by Ime2 has allowed us to propose a motif for phosphorylation by Ime2 (PXS/T) where serine or threonine acts as a phospho-acceptor. Although Ime2 phosphorylates Sic1 at multiple sites in vitro, the modified Sic1 fails to bind to SCF(Cdc4). In addition, the expression of Ime2 in G1 arrested haploid cells does not promote the destruction of Sic1. These data support a model where Ime2 is necessary but not sufficient to promote Sic1 destruction during sporulation.
Assuntos
Proteínas de Ciclo Celular/metabolismo , Proteínas Quinases/metabolismo , Proteínas de Saccharomyces cerevisiae/química , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Sítios de Ligação , Proteínas de Ciclo Celular/genética , Proteínas Inibidoras de Quinase Dependente de Ciclina , Estabilidade Enzimática , Fase G1/fisiologia , Regulação Fúngica da Expressão Gênica , Peptídeos e Proteínas de Sinalização Intracelular , Fosforilação , Proteínas Quinases/genética , Processamento de Proteína Pós-Traducional , Proteínas Serina-Treonina Quinases , Proteínas de Saccharomyces cerevisiae/genética , Esporos Fúngicos/metabolismoRESUMO
In proliferating S. cerevisiae, genes whose products function in DNA replication are regulated by the MBF transcription factor composed of Mbp1 and Swi6 that binds to consensus MCB sequences in target promoters. We find that during meiotic development a subset of DNA replication genes exemplified by TMP1 and RNR1 are regulated by Mbp1. Deletion of Mbp1 deregulated TMP1 and RNR1 but did not interfere with premeiotic S-phase, meiotic recombination, or spore formation. Surprisingly, deletion of MBP1 had no effect on the expression of CLB5, which is purportedly controlled by MBF. Extensive analysis of the CLB5 promoter revealed that the gene is largely regulated by elements within a 100-bp fragment containing a cluster of MCB sequences. Surprisingly, induction of the CLB5 promoter requires MCB sequences, but not Mbp1, implying that another MCB-binding factor may exist in cells undergoing meiosis. In addition, full activation of CLB5 during meiosis requires Clb5 activity, suggesting that CLB5 may be regulated by a positive feedback mechanism. We further demonstrate that during meiosis MCBs function as effective transcriptional activators independent of MBP1.
Assuntos
Ciclo Celular/genética , Ciclina B/genética , Replicação do DNA , DNA Fúngico/genética , Meiose/genética , Regiões Promotoras Genéticas , Fase S/genética , Proteínas de Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/genética , Fatores de Transcrição/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição/metabolismoRESUMO
Granzymes are a family of serine proteases that were once thought to function exclusively as mediators of cytotoxic lymphocyte-induced target cell death. However, non-apoptotic roles for granzymes, including granzyme K (GzK), have been proposed. As recent studies have observed elevated levels of GzK in the plasma of patients diagnosed with clinical sepsis, we hypothesized that extracellular GzK induces a proinflammatory response in endothelial cells. In the present study, extracellular GzK proteolytically activated protease-activated receptor-1 leading to increased interleukin 6 and monocyte chemotactic protein 1 production in endothelial cells. Enhanced expression of intercellular adhesion molecule 1 along with an increased capacity for adherence of THP-1 cells was also observed. Characterization of downstream pathways implicated the mitogen-activated protein kinase p38 pathway for intercellular adhesion molecule 1 expression, and both the p38 and the extracellular signal-regulated protein kinases 1 and 2 pathways in cytokine production. GzK also increased tumour necrosis factor α-induced inflammatory adhesion molecule expression. Furthermore, the physiological inhibitor of GzK, inter-α-inhibitor protein, significantly inhibited GzK activity in vitro. In summary, extracellular GzK promotes a proinflammatory response in endothelial cells.
Assuntos
Granzimas/farmacologia , Células Endoteliais da Veia Umbilical Humana/efeitos dos fármacos , Monócitos/efeitos dos fármacos , Receptor PAR-1/genética , alfa-Globulinas/farmacologia , Butadienos/farmacologia , Adesão Celular , Linhagem Celular , Quimiocina CCL2/genética , Quimiocina CCL2/metabolismo , Regulação da Expressão Gênica , Granzimas/antagonistas & inibidores , Granzimas/genética , Granzimas/metabolismo , Células Endoteliais da Veia Umbilical Humana/citologia , Células Endoteliais da Veia Umbilical Humana/metabolismo , Humanos , Imidazóis/farmacologia , Interleucina-6/genética , Interleucina-6/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 1 Ativada por Mitógeno/genética , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Proteína Quinase 3 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 3 Ativada por Mitógeno/genética , Proteína Quinase 3 Ativada por Mitógeno/metabolismo , Monócitos/citologia , Monócitos/metabolismo , Nitrilas/farmacologia , Proteólise/efeitos dos fármacos , Piridinas/farmacologia , Receptor PAR-1/antagonistas & inibidores , Receptor PAR-1/metabolismo , Transdução de Sinais , Proteínas Quinases p38 Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases p38 Ativadas por Mitógeno/genética , Proteínas Quinases p38 Ativadas por Mitógeno/metabolismoRESUMO
During HIV-1 infection a population of latently infected cells is established. This population is the major obstacle preventing total eradication of the virus from AIDS patients. HIV-1 latency is thought to arise by various mechanisms including repressive chromatin modifications. Transcription factors such as YY1 have been shown to facilitate repressive chromatin modifications by the recruitment of histone deacetylases. In this study, we identified a novel binding site for YY1 on the HIV-1 LTR, 120 nucleotides upstream of the transcription start site. We show that YY1 can bind to this site in vitro and in vivo and that binding to the LTR is dissociated upon T cell activation. Overexpression of YY1 causes an increase in the proportion of cells that produce latent infections. These observations, in combination with previous results, demonstrate that YY1 plays a prominent role in controlling the establishment and maintenance of latent HIV-1 provirus in unstimulated cells.
Assuntos
Regulação Viral da Expressão Gênica , Infecções por HIV/genética , Repetição Terminal Longa de HIV , HIV-1/fisiologia , Latência Viral , Fator de Transcrição YY1/metabolismo , Animais , Sequência de Bases , Sítios de Ligação , Células HEK293 , Infecções por HIV/metabolismo , Histona Desacetilases/metabolismo , Humanos , Células Jurkat , Regulação para CimaRESUMO
PhosphoGRID is an online database that curates and houses experimentally verified in vivo phosphorylation sites in the Saccharomyces cerevisiae proteome (www.phosphogrid.org). Phosphosites are annotated with specific protein kinases and/or phosphatases, along with the condition(s) under which the phosphorylation occurs and/or the effects on protein function. We report here an updated data set, including nine additional high-throughput (HTP) mass spectrometry studies. The version 2.0 data set contains information on 20 177 unique phosphorylated residues, representing a 4-fold increase from version 1.0, and includes 1614 unique phosphosites derived from focused low-throughput (LTP) studies. The overlap between HTP and LTP studies represents only â¼3% of the total unique sites, but importantly 45% of sites from LTP studies with defined function were discovered in at least two independent HTP studies. The majority of new phosphosites in this update occur on previously documented proteins, suggesting that coverage of phosphoproteins in the yeast proteome is approaching saturation. We will continue to update the PhosphoGRID data set, with the expectation that the integration of information from LTP and HTP studies will enable the development of predictive models of phosphorylation-based signaling networks. Database URL: http://www.phosphogrid.org/
Assuntos
Bases de Dados de Proteínas , Fosfoproteínas/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/metabolismo , Ensaios de Triagem em Larga Escala , Fosforilação , Proteoma/metabolismo , Transdução de SinaisRESUMO
The yeast Saccharomyces differentiates into filamentous pseudohyphae when exposed to a poor source of nitrogen in a process involving a collection of transcription factors regulated by nutrient signaling pathways. Phd1 is important for this process in that it regulates expression of most other transcription factors involved in differentiation and can induce filamentation on its own when overproduced. In this article, we show that Phd1 is an unstable protein whose degradation is initiated through phosphorylation by Cdk8 of the RNA polymerase II mediator subcomplex. Phd1 is stabilized by cdk8 disruption, and the naturally filamenting Σ1278b strain was found to have a sequence polymorphism that eliminates a Cdk8 phosphorylation site, which both stabilizes the protein and contributes to enhanced differentiation. In nitrogen-starved cells, PHD1 expression is upregulated and the Phd1 protein becomes stabilized, which causes its accumulation during differentiation. PHD1 expression is partially dependent upon Ste12, which was also previously shown to be destabilized by Cdk8-dependent phosphorylations, but to a significantly smaller extent than Phd1. These observations demonstrate the central role that Cdk8 plays in initiation of differentiation. Cdk8 activity is inhibited in cells shifted to limiting nutrient conditions, and we argue that this effect drives the initiation of differentiation through stabilization of multiple transcription factors, including Phd1, that cause activation of genes necessary for filamentous response.
Assuntos
Quinase 8 Dependente de Ciclina/metabolismo , Proteínas de Ligação a DNA/metabolismo , Proteínas de Saccharomyces cerevisiae/metabolismo , Saccharomyces cerevisiae/citologia , Saccharomyces cerevisiae/metabolismo , Fatores de Transcrição/metabolismo , Quinase 8 Dependente de Ciclina/genética , Proteínas de Ligação a DNA/genética , Regulação Fúngica da Expressão Gênica , Polimorfismo Genético , Estabilidade Proteica , RNA Polimerase II/genética , RNA Polimerase II/metabolismo , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Fatores de Transcrição/genéticaRESUMO
Flow cytometry is important tool for investigating DNA replication in sporulating Saccharomyces cerevisiae. However, flow cytometry data from maturing spores is often difficult to interpret due to extensive broadening of the fluorescence peaks. This problem is markedly improved by treatment of the spores with potassium hydroxide prior to staining.
Assuntos
Replicação do DNA , DNA Fúngico/metabolismo , Citometria de Fluxo/métodos , Corantes Fluorescentes/farmacologia , Saccharomyces cerevisiae/fisiologia , Coloração e Rotulagem/métodosRESUMO
The spliceosome is a complex ribonucleoprotein (RNP) particle containing five RNAs and more than 100 associated proteins. One of these proteins, PRP8, has been shown to interact directly with the splice sites and branch region of precursor-mRNAs (pre-mRNAs) and spliceosomal RNAs associated with catalysis of the two steps of splicing. The 1.85-A X-ray structure of the core of PRP8 domain IV, implicated in key spliceosomal interactions, reveals a bipartite structure that includes the presence of an RNase H fold linked to a five-helix assembly. Analysis of mutant yeast alleles and cross-linking results in the context of this structure, coupled with RNA binding studies, suggests that domain IV forms a surface that interacts directly with the RNA structures at the catalytic core of the spliceosome.