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1.
Front Sports Act Living ; 4: 1060851, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36685066

RESUMO

Athlete health and wellbeing requires a holistic, multidimensional approach to understanding, supporting, and treating individual athletes. Building more supportive, inclusive, and equitable environments for the health and wellbeing of women and gender expansive people further requires gender-responsive approaches that promote broader cultural change. Feminist sport and exercise medicine practitioners, sports scientists, and social science researchers are increasingly coming together in their efforts to do this work. However, working across disciplines inevitably includes an array of ontological, epistemological, and political challenges. In this paper, we offer a curated 'dialogue' with a group of feminist scholars engaged in research and practice across disciplines, bringing them together to discuss some of the most pressing gendered issues in sport today (i.e., ACL injury, concussion, menstruation in sport, mental health, gender categories). In so doing, we amplify the voices of those working (empirically and clinically) at the disciplinary intersections of gender, sport and health, and learn about some of the current and future possibilities for transdisciplinary innovations and strategies for building (responsiveness to) cultural change.

2.
Hum Reprod ; 26(1): 47-58, 2011 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-21088015

RESUMO

BACKGROUND: Spermatozoa with large vacuoles (SLV) may have a negative impact on embryo development. The origin of these vacuoles is unknown. We evaluated acrosome and nucleus alterations in isolated SLV, versus unselected spermatozoa. METHODS: We studied 20 patients with teratozoospermia. Spermatozoa from the native semen sample and spermatozoa presenting a vacuole occupying >13.0% total head area, isolated under high magnification (×6600), were assessed. Confocal and transmission electron microscope evaluations were performed on SLV and native sperm, respectively. Acrosome morphology and DNA fragmentation were analysed using proacrosin immunolabelling (monoclonal antibody 4D4) and terminal deoxynucleotidyl transferase-mediated dUTP nick end labelling assay. Chromatin condensation was evaluated with aniline blue staining. Sperm aneuploidy was assessed using fluorescence in situ hybridization. RESULTS: SLV represented 38.0 ± 5.10% of motile spermatozoa obtained after gradient density centrifugation. Vacuoles were mainly in the anterior and median sperm head (45.7 ± 2.90 and 46.1 ± 3.00%, respectively). Abnormal acrosomes were increased in SLV compared with unselected spermatozoa (77.8 ± 2.49 versus 70.6 ± 2.62%; P = 0.014). Microscopic observations showed an exclusively nuclear localization of large vacuoles. Complete DNA fragmentation was higher in native spermatozoa (P < 0.0001) than SLV, while chromatin condensation was altered in SLV (P < 0.0001). Aneuploidy and diploidy rates were increased in SLV (P < 0.0001). CONCLUSIONS: Sperm vacuoles were exclusively nuclear. In our selected teratozoospermic population, aneuploidy and chromatin condensation defects were the main alterations observed in SLV. Based on results from this small sample of spermatozoa, we propose a global impairment of the spermatogenesis process as a common origin of the morphological alterations.


Assuntos
Acrossomo/ultraestrutura , Infertilidade Masculina/patologia , Análise do Sêmen/métodos , Espermatozoides/ultraestrutura , Vacúolos/ultraestrutura , Adulto , Aneuploidia , Núcleo Celular/ultraestrutura , Cromatina/ultraestrutura , Fragmentação do DNA , Desenvolvimento Embrionário , Humanos , Hibridização in Situ Fluorescente , Marcação In Situ das Extremidades Cortadas , Masculino , Microscopia Eletrônica de Transmissão , Pessoa de Meia-Idade
3.
Trends Biochem Sci ; 16(3): 92-7, 1991 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-1647556

RESUMO

Many proteins have the ability to bind to a variety of DNA sequences, the recognition of which depends on some general rather than specific feature of the DNA. Some of the protein motifs that are responsible for this type of recognition have been identified in transcription factors and chromosomal proteins. These motifs consist of sequences capable of forming a structural framework in which positively charged residues can be arranged so that binding to a particular DNA structure is preferred.


Assuntos
DNA/química , Proteínas/química , Sequência de Aminoácidos , Sítios de Ligação , Conformação Molecular , Dados de Sequência Molecular , Netropsina/química , Relação Estrutura-Atividade
4.
Trends Biochem Sci ; 26(3): 167-74, 2001 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-11246022

RESUMO

The HMG-box proteins, one of the three classes of high mobility group (HMG) chromosomal proteins, bend DNA and bind preferentially to distorted DNA structures. The proteins appear to act primarily as architectural facilitators in the assembly of nucleoprotein complexes; for example, in effecting recombination and in the initiation of transcription. HMG-box proteins might be targeted to particular DNA sites in chromatin by either protein-protein interactions or recognition of specific DNA structures.


Assuntos
Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/metabolismo , Sequência de Aminoácidos , Proteínas de Ligação a DNA/química , Proteínas de Grupo de Alta Mobilidade/química , Humanos , Dados de Sequência Molecular , Conformação Proteica , Homologia de Sequência de Aminoácidos
5.
Br J Oral Maxillofac Surg ; 57(2): 125-134, 2019 02.
Artigo em Inglês | MEDLINE | ID: mdl-30658870

RESUMO

The ability of patients to participate in recreational activities is an important facet of health-related quality of life (HRQoL) after treatment for cancer of the head and neck. The aim of this study was to analyse patients' responses to the activity and recreation domains of the University of Washington quality of life questionnaire (UW-QoL), and to relate them to clinical characteristics, the intensity of leisure-time exercise/week, perceived barriers that interfere with exercise, and feeling able to participate in an exercise programme. Other questionnaires used were the Godin Leisure-Time Exercise questionnaire, the Perceived Exercise Barriers questionnaire, and the Exercise Preferences questionnaire. The survey sample comprised 1021 patients of whom 437 responded (43%). Of them, 9% reported a serious problem with activity and 8% with recreation. The main influencing factors were site (oropharynx), advanced stage, radiotherapy and chemotherapy, composite flap, gastrostomy tube, and coexisting conditions. Low (worse) scores in the UW-QoL activity and recreation domains were associated with little time spent exercising, low-intensity exercise, more barriers to exercising, and a lack of preference. The use of the UW-QoL in follow-up assessments can help to identify patients who are having difficulties in these two domains, as well as those who feel able to participate in an exercise programme. Further research is required to optimise the interventions that will promote exercise and improve recovery and wellbeing.


Assuntos
Neoplasias de Cabeça e Pescoço , Qualidade de Vida , Gastrostomia , Humanos , Recreação , Inquéritos e Questionários
6.
Curr Biol ; 9(1): R23-5, 1999 Jan 14.
Artigo em Inglês | MEDLINE | ID: mdl-9889114

RESUMO

Specific patterns of acetylation of the core histones are associated with specific structures and functions of chromatin. A basis for the specificity of acetylation is now apparent in the recent crystal structures of two acetyltransferases.


Assuntos
Acetiltransferases/metabolismo , Cromatina/fisiologia , Histonas/metabolismo , Acetilação , Acetiltransferases/química , Cromatina/enzimologia , Ativação Enzimática , Histona Acetiltransferases , Histonas/química , Especificidade por Substrato
7.
Curr Biol ; 7(4): R252-4, 1997 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-9162504

RESUMO

The crystal structure of Escherichia coli integration host factor complexed with DNA reveals how the sequence-specificity of DNA binding can be determined almost entirely by the structural features of the DNA itself and not by direct readout of the base sequence. There are lessons to be drawn for other DNA-binding motifs.


Assuntos
Proteínas de Bactérias/química , Proteínas de Ligação a DNA/química , DNA/química , Conformação de Ácido Nucleico , Estrutura Secundária de Proteína , Sequência de Aminoácidos , Animais , Proteínas de Bactérias/metabolismo , Sequência de Bases , Sítios de Ligação , Sequência Conservada , DNA/metabolismo , Proteínas de Ligação a DNA/metabolismo , Escherichia coli/metabolismo , Humanos , Fatores Hospedeiros de Integração , Substâncias Macromoleculares , Modelos Estruturais
8.
Curr Biol ; 6(4): 401-3, 1996 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-8723344

RESUMO

Recent crystal and solution structures of components of the core transcription initiation complex that assembles at RNA polymerase II promoters reveal similarities to core histones and cyclin A.


Assuntos
Regiões Promotoras Genéticas , RNA Polimerase II/genética , Transcrição Gênica , Animais , Ciclinas , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Histonas/química , Humanos , Modelos Moleculares , TATA Box , Proteína de Ligação a TATA-Box , Fator de Transcrição TFIIB , Fatores de Transcrição/química , Fatores de Transcrição/metabolismo
9.
Curr Biol ; 8(17): R616-8, 1998 Aug 27.
Artigo em Inglês | MEDLINE | ID: mdl-9742392

RESUMO

The cooperative formation of a higher-order complex between transcription factors NFAT and Fos-Jun is accompanied by conformational changes in both DNA and protein. This allows formation of an extended interface between the proteins, while conserving recognition of the core DNA binding sequences.


Assuntos
DNA/química , Fatores de Transcrição/química , Ativação Transcricional/fisiologia , Conformação de Ácido Nucleico , Conformação Proteica
10.
Curr Biol ; 4(7): 659-61, 1994 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-7953550

RESUMO

A new model system has been used to demonstrate how a nucleosome may remain associated with an actively transcribed gene and yet maintain DNA compaction during transcription.


Assuntos
Proteínas de Ligação a DNA/metabolismo , DNA/metabolismo , Modelos Genéticos , Nucleossomos/fisiologia , Transcrição Gênica/fisiologia , Cromatina/metabolismo , Cromatina/ultraestrutura , DNA/genética , DNA Helicases/metabolismo , DNA Super-Helicoidal/genética , DNA Super-Helicoidal/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Ligação Proteica
11.
N Engl J Med ; 351(7): 637-46, 2004 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-15306665

RESUMO

BACKGROUND: The rate of survival after out-of-hospital cardiac arrest is low. It is not known whether this rate will increase if laypersons are trained to attempt defibrillation with the use of automated external defibrillators (AEDs). METHODS: We conducted a prospective, community-based, multicenter clinical trial in which we randomly assigned community units (e.g., shopping malls and apartment complexes) to a structured and monitored emergency-response system involving lay volunteers trained in cardiopulmonary resuscitation (CPR) alone or in CPR and the use of AEDs. The primary outcome was survival to hospital discharge. RESULTS: More than 19,000 volunteer responders from 993 community units in 24 North American regions participated. The two study groups had similar unit and volunteer characteristics. Patients with treated out-of-hospital cardiac arrest in the two groups were similar in age (mean, 69.8 years), proportion of men (67 percent), rate of cardiac arrest in a public location (70 percent), and rate of witnessed cardiac arrest (72 percent). No inappropriate shocks were delivered. There were more survivors to hospital discharge in the units assigned to have volunteers trained in CPR plus the use of AEDs (30 survivors among 128 arrests) than there were in the units assigned to have volunteers trained only in CPR (15 among 107; P=0.03; relative risk, 2.0; 95 percent confidence interval, 1.07 to 3.77); there were only 2 survivors in residential complexes. Functional status at hospital discharge did not differ between the two groups. CONCLUSIONS: Training and equipping volunteers to attempt early defibrillation within a structured response system can increase the number of survivors to hospital discharge after out-of-hospital cardiac arrest in public locations. Trained laypersons can use AEDs safely and effectively.


Assuntos
Reanimação Cardiopulmonar , Cardioversão Elétrica , Serviços Médicos de Emergência , Parada Cardíaca/terapia , Voluntários , Adolescente , Adulto , Idoso , Idoso de 80 Anos ou mais , Comércio , Feminino , Parada Cardíaca/mortalidade , Hospitalização , Habitação , Humanos , Masculino , Pessoa de Meia-Idade , Estudos Prospectivos , Método Simples-Cego , Análise de Sobrevida
12.
Mol Cell Biol ; 20(3): 1072-82, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10629064

RESUMO

The ubiquitin-related SUMO-1 modifier can be covalently attached to a variety of proteins. To date, four substrates have been characterized in mammalian cells: RanGAP1, IkappaBalpha, and the two nuclear body-associated PML and Sp100 proteins. SUMO-1 modification has been shown to be involved in protein localization and/or stabilization and to require the activity of specialized E1-activating and E2 Ubc9-conjugating enzymes. SUMO-1 homologues have been identified in various species and belong to the so-called Smt3 family of proteins. Here we have characterized the Drosophila homologues of mammalian SUMO-1 and Ubc9 (termed dSmt3 and dUbc9, respectively). We show that dUbc9 is the conjugating enzyme for dSmt3 and that dSmt3 can covalently modify a number of proteins in Drosophila cells in addition to the human PML substrate. The dSmt3 transcript and protein are maternally deposited in embryos, where the protein accumulates predominantly in nuclei. Similar to its human counterpart, dSmt3 protein is observed in a punctate nuclear pattern. We demonstrate that Tramtrack 69 (Ttk69), a repressor of neuronal differentiation, is a bona fide in vivo substrate for dSmt3 conjugation. Finally, we show that both the modified and unmodified forms of Ttk69 can bind to a Ttk69 binding site in vitro. Moreover, dSmt3 and Ttk69 proteins colocalize on polytene chromosomes, indicating that the dSmt3-conjugated Ttk69 species can bind at sites of Ttk69 action in vivo. Altogether, these data indicate a high conservation of the Smt3 conjugation pathway and further suggest that this mechanism may play a role in the transcriptional regulation of cell differentiation in Drosophila flies.


Assuntos
Proteínas de Drosophila , Drosophila/genética , Proteínas Repressoras/genética , Proteínas Repressoras/metabolismo , Transcrição Gênica , Sequência de Aminoácidos , Animais , Cromossomos/fisiologia , Drosophila/embriologia , Biblioteca Gênica , Células HeLa , Humanos , Dados de Sequência Molecular , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Proteínas Repressoras/química , Proteína SUMO-1 , Alinhamento de Sequência , Homologia de Sequência de Aminoácidos , Proteínas Modificadoras Pequenas Relacionadas à Ubiquitina , Transfecção , Ubiquitinas/química , Ubiquitinas/metabolismo
13.
Curr Opin Struct Biol ; 10(1): 102-9, 2000 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-10679469

RESUMO

Recent biochemical and structural studies have shown that the preferential recognition of distorted DNA structures, including DNA bulges, four-way junctions and cis-platinated DNA, by HMG domains is dependent on residues immediately preceding the second alpha helix of the L-shaped HMG domain.


Assuntos
Dano ao DNA , Proteínas de Grupo de Alta Mobilidade/metabolismo , Conformação de Ácido Nucleico , Sequência de Aminoácidos , Reparo do DNA , Proteínas de Grupo de Alta Mobilidade/química , Substâncias Macromoleculares , Modelos Moleculares , Dados de Sequência Molecular , Ligação Proteica , Estrutura Terciária de Proteína , Alinhamento de Sequência , Homologia de Sequência do Ácido Nucleico , Especificidade por Substrato
14.
Nat Biotechnol ; 19(6): 559-62, 2001 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-11385461

RESUMO

Nuclear transfer offers a cell-based route for producing precise genetic modifications in a range of animal species. Using sheep, we report reproducible targeted gene deletion at two independent loci in fetal fibro-blasts. Vital regions were deleted from the alpha(1,3)galactosyl transferase (GGTA1) gene, which may account for the hyperacute rejection of xenografted organs, and from the prion protein (PrP) gene, which is directly associated with spongiform encephalopathies in humans and animals. Reconstructed embryos were prepared using cultures of targeted or nontargeted donor cells. Eight pregnancies were maintained to term and four PrP-/+ lambs were born. Although three of these perished soon after birth, one survived for 12 days. These data show that lambs carrying targeted gene deletions can be generated by nuclear transfer.


Assuntos
Animais Geneticamente Modificados , Galactosiltransferases/genética , Deleção de Genes , Técnicas de Transferência de Genes , Príons/genética , Animais , Animais Recém-Nascidos , Southern Blotting , Núcleo Celular/metabolismo , Éxons , Fibroblastos/metabolismo , Marcação de Genes , Modelos Genéticos , Ovinos , Fatores de Tempo , Transfecção
15.
Nucleic Acids Res ; 29(24): 5107-14, 2001 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-11812843

RESUMO

The Escherichia coli chromatin protein FIS modulates the topology of DNA in a growth phase-dependent manner. In this study we have investigated the global effect of FIS binding on DNA architecture in vitro. We show that in supercoiled DNA molecules FIS binds at multiple sites in a non-random fashion and increases DNA branching. This global DNA reshaping effect is independent of the helical phasing of FIS binding sites. We propose, in addition to the previously inferred stabilisation of tightly bent DNA microloops in the upstream regions of certain promoters, that FIS may perform the distinct architectural function of organising branched plectonemes in the E.coli nucleoid.


Assuntos
Proteínas de Transporte/metabolismo , DNA Bacteriano/química , Proteínas de Escherichia coli , Escherichia coli/genética , Proteínas de Transporte/fisiologia , DNA Bacteriano/metabolismo , DNA Bacteriano/ultraestrutura , DNA Super-Helicoidal/química , DNA Super-Helicoidal/metabolismo , DNA Super-Helicoidal/ultraestrutura , Escherichia coli/química , Fator Proteico para Inversão de Estimulação , Fatores Hospedeiros de Integração , Microscopia de Força Atômica , Microscopia Eletrônica , Conformação de Ácido Nucleico , Plasmídeos/química , Plasmídeos/metabolismo , Plasmídeos/ultraestrutura , Ligação Proteica
16.
Nucleic Acids Res ; 27(24): 4768-74, 1999 Dec 15.
Artigo em Inglês | MEDLINE | ID: mdl-10572177

RESUMO

Promoter sequences of Escherichia coli were compiled and their transcribed regions characterized by site-specific cluster analysis. Here we report that transcribed regions contain a non-random distribution of A/T tracts with strongly preferred positions at 6 +/- 3, 23 +/- 3, 40 +/- 2 and 56 +/- 2. The maxima of this distribution follow an unusual periodicity (approximately 17 bp) and are in phase with important promoter elements involved in interaction with RNA polymerase, while the value of periodicity numerically fits the spacer length between the canonical -35 and -10 elements. The possible functional significance of this newly described feature is discussed in the context of promoter clearance and transcription pausing.


Assuntos
Composição de Bases , DNA Bacteriano/química , Escherichia coli/genética , Regiões Promotoras Genéticas , Transcrição Gênica , Adenina , Sequência de Bases , Bases de Dados como Assunto , Dados de Sequência Molecular , Timina
17.
Structure ; 2(7): 609-27, 1994 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-7922039

RESUMO

BACKGROUND: The HMG-box is a conserved DNA-binding motif that has been identified in many high mobility group (HMG) proteins. HMG-D is a non-histone chromosomal protein from Drosophila melanogaster that is closely related to the mammalian HMG-box proteins HMG-1 and HMG-2. Previous structures determined for an HMG-box domain from rat and hamster exhibit the same global topology, but differ significantly in detail. It has been suggested that these differences may arise from hinge motions which allow the protein to adapt to the shape of its target DNA. RESULTS: We present the solution structure of HMG-D determined by NMR spectroscopy to an overall precision of 0.85 A root mean squared deviation (rmsd) for the backbone atoms. The protein consists of an extended amino-terminal region and three alpha-helices that fold into a characteristic 'L' shape. The central core region of the molecule is highly stable and maintains an angle of approximately 80 degrees between the axes of helices 2 and 3. The backbone dynamics determined from 15N NMR relaxation measurements show a high correlation with the mean residue rmsd determined from the calculated structures. CONCLUSIONS: The structure determined for the HMG-box motif from HMG-D is essentially identical to the structure determined for the B-domain of mammalian HMG-1. Since these proteins have significantly different sequences our results indicate that the global fold and the mode of interaction with DNA are also likely to be conserved in all eukaryotes.


Assuntos
Proteínas de Ligação a DNA/química , Drosophila melanogaster/química , Proteínas de Grupo de Alta Mobilidade/química , Sequência de Aminoácidos , Animais , Sequência de Bases , Simulação por Computador , DNA/metabolismo , Proteínas de Ligação a DNA/genética , Proteínas de Ligação a DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/genética , Proteínas de Grupo de Alta Mobilidade/metabolismo , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Dados de Sequência Molecular , Conformação Proteica , Estrutura Secundária de Proteína , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Homologia de Sequência de Aminoácidos , Soluções/química
18.
CJEM ; 18(3): 213-22, 2016 May.
Artigo em Inglês | MEDLINE | ID: mdl-26832320

RESUMO

OBJECTIVE: Two major processes underlie human decision-making: experiential (intuitive) and rational (conscious) thinking. The predominant thinking process used by working paramedics and student paramedics to make clinical decisions is unknown. METHODS: A survey was administered to ground ambulance paramedics and to primary care paramedic students. The survey included demographic questions and the Rational Experiential Inventory-40, a validated psychometric tool involving 40 questions. Twenty questions evaluated each thinking style: 10 assessed preference and 10 assessed ability to use that style. Responses were provided on a five-point Likert scale, with higher scores indicating higher affinity for the style in question. Analysis included both descriptive statistics and t tests to evaluate differences in thinking style. RESULTS: The response rate was 88.4% (1172/1326). Paramedics (n=904) had a median age of 36 years (IQR 29-42) and most were male (69.5%) and primary or advanced care paramedics (PCP=55.5%; ACP=32.5%). Paramedic students (n=268) had a median age of 23 years (IQR 21-26), most were male (63.1%) and had completed high school (31.7%) or an undergraduate degree (25.4%) prior to paramedic training. Both groups scored their ability to use and favourability toward rational thinking significantly higher than experiential thinking. The mean score for rational thinking was 3.86/5 among paramedics and 3.97/5 among paramedic students (p<0.001). The mean score for experiential thinking was 3.41/5 among paramedics and 3.35/5 among paramedic students (p=0.06). CONCLUSION: Working paramedics and student paramedics prefer and perceive that they have the ability to use rational over experiential thinking. This information adds to our current knowledge on paramedic decision-making and is potentially important for developing continuing education and clinical support tools.


Assuntos
Pessoal Técnico de Saúde/psicologia , Tomada de Decisões , Medicina de Emergência/educação , Adulto , Estudos Transversais , Feminino , Humanos , Masculino , Nova Escócia , Psicometria , Inquéritos e Questionários , Pensamento
19.
J Mol Biol ; 279(5): 1027-43, 1998 Jun 26.
Artigo em Inglês | MEDLINE | ID: mdl-9642081

RESUMO

Prokaryotic transcriptional activation often involves the formation of DNA microloops upstream of the polymerase binding site. There is substantial evidence that these microloops function to bring activator and polymerase into close spatial proximity. However additional functions are suggested by the ability of certain activators, of which FIS is the best characterised example, to facilitate polymerase binding, promoter opening and polymerase escape. We review here the evidence for the concept that the topology of the microloop formed by such activators is tightly coupled to the structural transitions in DNA mediated by RNA polymerase. In this process, which we term torsional transmission, a major function of the activator is to act as a local topological homeostat. We argue that the same mechanism may also be employed in site-specific DNA inversion.


Assuntos
DNA Bacteriano/química , Proteínas de Escherichia coli , Conformação de Ácido Nucleico , Ativação Transcricional , Proteínas de Transporte/metabolismo , RNA Polimerases Dirigidas por DNA/metabolismo , Escherichia coli/genética , Fator Proteico para Inversão de Estimulação , Regulação Bacteriana da Expressão Gênica , Fatores Hospedeiros de Integração , Regiões Promotoras Genéticas/genética , Fator sigma/metabolismo , Fatores de Transcrição/metabolismo
20.
J Mol Biol ; 266(1): 66-75, 1997 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-9054971

RESUMO

HMG-D is one of the Drosophila counterparts of the vertebrate HMG1/2 class of abundant chromosomal proteins and contains three domains: an HMG domain followed by a basic region and a short acidic carboxyterminal tail. We show that the HMG domain of HMG-D does not bind to deformed DNA structures such as DNA bulges, cis-platinated DNA or four-way junctions but does bind tightly to DNA microcircles, suggesting that in vivo the natural ligands of this domain are tightly bent DNA loops. The flanking basic region substantially increases the DNA-binding activity of the HMG domain to DNA ligands other than microcircles. We demonstrate that the acidic tail alters the structural selectivity of DNA binding by increasing the affinity for deformed DNA and decreasing the affinity for linear B-DNA. Finally, we show that the acidic tail increases the efficiency of constraining preformed negative supercoils but conversely decreases the efficiency of supercoiling relaxed DNA in the presence of topoisomerase I.


Assuntos
DNA Super-Helicoidal/metabolismo , DNA/metabolismo , Proteínas de Grupo de Alta Mobilidade/química , Proteínas de Grupo de Alta Mobilidade/metabolismo , Sequência de Aminoácidos , Animais , Sequência de Bases , DNA/química , DNA Topoisomerases Tipo I/metabolismo , DNA Super-Helicoidal/química , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/metabolismo , Drosophila , Dados de Sequência Molecular , Oligodesoxirribonucleotídeos , Plasmídeos , Especificidade por Substrato , Vertebrados
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