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1.
Br J Dermatol ; 190(5): 668-679, 2024 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-38226713

RESUMO

BACKGROUND: In the phase III POETYK PSO-1 and PSO-2 trials, deucravacitinib, an oral selective allosteric tyrosine kinase 2 inhibitor, was well tolerated and efficacious over 1 year in patients with psoriasis. OBJECTIVE: To evaluate deucravacitinib safety and efficacy over 2 years in patients participating in the phase III trials. METHODS: In the POETYK long-term extension (LTE), an ongoing phase IIIb open-label trial, adults with moderate-to-severe plaque psoriasis who completed PSO-1 or PSO-2 receive deucravacitinib 6 mg once daily. Safety was assessed via adverse events (AEs) and laboratory parameter abnormalities. Efficacy endpoints, including ≥ 75% reduction from baseline Psoriasis Area and Severity Index score (PASI 75) and static Physician's Global Assessment (sPGA) score of 0/1 (clear/almost clear), were evaluated in patients originally randomized to deucravacitinib, patients who crossed over from placebo at week 16 and patients who achieved PASI 75 at week 24 (peak efficacy). RESULTS: At data cutoff (1 October 2021), 1519 patients had received at least one dose of deucravacitinib; 79.0% and 39.9% had ≥ 52 weeks and ≥ 104 weeks of total deucravacitinib exposure, respectively. Exposure-adjusted incidence rates (EAIRs) per 100 person-years were similar at 1 year and 2 years for any AEs (229.2 vs. 154.4, respectively), serious AEs (5.7 vs. 6.1), discontinuations (4.4 vs. 2.8), deaths (0.2 vs. 0.4), serious infections (1.7 vs. 2.6), herpes zoster (0.9 vs. 0.8), major adverse cardiovascular events (0.3 vs. 0.4), venous thromboembolic events (0.2 vs. 0.1) and malignancies (1.0 vs. 0.9). EAIRs for COVID-19 infections were higher at 2 years than at 1 year (5.1 vs. 0.5) owing to the peak of the global COVID-19 pandemic occurring during the LTE. No clinically meaningful changes from baseline or trends were observed over 2 years in haematological, chemistry or lipid parameters. Clinical responses were maintained in patients who received continuous deu-cravacitinib treatment from baseline [PASI 75: week 52, 72.4%; week 112, 79.7%; sPGA 0/1: week 52, 57.9%; week 112, 61.1% (as observed)]. Responses at week 52 were also maintained in placebo crossovers and in week-24 PASI-75 responders. CONCLUSIONS: Deucravacitinib maintained efficacy and demonstrated consistent safety with no new safety signals observed through 2 years.


Psoriasis is a chronic inflammatory skin condition. Many available treatments for psoriasis are injected, but can be inadequate in terms of effectiveness, and/or cause serious side-effects. Deucravacitinib is a recently approved oral medicine that interferes with an enzyme involved in inflammation called 'tyrosine kinase 2' (TYK2). Deucravacitinib has been shown to improve psoriatic patches and symptoms (such as itching) through 1 year in two global clinical trials in adults with moderate-to-severe plaque psoriasis (POETYK PSO-1 and PSO-2). This study was an analysis of the safety and efficacy of deu­cravacitinib for up to 2 years. To do this, the researchers used data from approximately 1500 people who completed both trials and continued into an ongoing, long-term extension trial (POETYK LTE). Overall, there were no new side-effects, and the number, type and severity of side-effects, as well as the number of patients who stopped treatment because of these side-effects, remained low. The most frequent side-effects included common cold symptoms and COVID-19. Rates of shingles and serious side-effects were comparable to rates reported in the real world. Improvements in psoriasis symptoms seen at 1 year were maintained for up to 2 years in patients receiving deucravacitinib treatment from the start of PSO-1 or PSO-2, or who crossed over from placebo to deucravacitinib at 4 months. Long-term treatment with deucravacitinib improved psoriasis symptoms and resulted in mostly mild side-effects. The study findings suggest that deucravacitinib could be a well-tolerated and effective treatment for people with psoriasis.


Assuntos
Compostos Heterocíclicos , Pandemias , Psoríase , Adulto , Humanos , Índice de Gravidade de Doença , Psoríase/tratamento farmacológico , Resultado do Tratamento , Método Duplo-Cego
2.
J Dermatol ; 51(3): 365-379, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38268101

RESUMO

Deucravacitinib, an oral, selective, allosteric tyrosine kinase 2 inhibitor, is approved in Japan for adult patients with plaque (PP), generalized pustular (GPP), and erythrodermic (EP) psoriasis who have had an inadequate response to conventional systemic therapies. This approval is based on results from the global phase 3 POETYK PSO-1 and PSO-2 trials in which deucravacitinib was associated with significantly improved efficacy outcomes compared with placebo in adults with moderate to severe plaque psoriasis, and results described here from POETYK PSO-4, an open-label, single-arm, phase 3 trial (NCT03924427), which evaluated the efficacy and safety of deucravacitinib 6 mg once daily in adult Japanese patients with PP, GPP, or EP. The coprimary endpoints were the proportion of patients achieving a ≥75% reduction from baseline in the Psoriasis Area and Severity Index (PASI 75) and a static Physician's Global Assessment score of 0 (clear) or 1 (almost clear) (sPGA 0/1) with at least a two-point improvement from baseline at week 16. Nonresponder imputation was used for missing data. Efficacy responses, adverse events (AEs), and serious AEs (SAEs) were recorded for up to 52 weeks. Seventy-four patients were treated (PP, n = 63; GPP, n = 3; EP, n = 8). At week 16, 76.2%, 66.7%, and 37.5% of patients with PP, GPP, and EP, respectively, had achieved PASI 75, and 82.5%, 0.0%, and 50.0% had achieved sPGA 0/1. Responses were overall maintained through week 52. AEs occurred in 74.6% of patients with PP, 100% of patients with GPP, and 87.5% of patients with EP. The most common AEs were nasopharyngitis and acne. Rates of SAEs and discontinuations were low. There were no deaths. Deucravacitinib was effective and well tolerated in Japanese patients with moderate to severe PP and in a limited number of patients with GPP or EP.


Assuntos
Exantema , Compostos Heterocíclicos , Psoríase , Dermatopatias Vesiculobolhosas , Adulto , Humanos , Japão , TYK2 Quinase/uso terapêutico , Anticorpos Monoclonais Humanizados/uso terapêutico , Resultado do Tratamento , Índice de Gravidade de Doença , Psoríase/tratamento farmacológico , Psoríase/induzido quimicamente , Doença Crônica , Doença Aguda , Exantema/tratamento farmacológico , Dermatopatias Vesiculobolhosas/tratamento farmacológico , Método Duplo-Cego
3.
JAMA Dermatol ; 160(2): 204-209, 2024 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-38117487

RESUMO

Importance: Change from baseline score on the validated Psoriasis Symptoms and Signs Diary (PSSD) is a widely used, patient-reported end point in clinical trials for psoriasis. Meaningful score change thresholds anchored to patient-reported assessments have not been established in a clinical trial setting. Objective: To evaluate meaningful within-patient score change thresholds for the PSSD using data from the phase 3 Program to Evaluate the Efficacy and Safety of Deucravacitinib, a Selective TYK2 Inhibitor (POETYK), PSO-1 clinical trial, which compared the efficacy and safety of deucravacitinib vs placebo and apremilast among adults with moderate to severe plaque psoriasis. Design, Setting, and Participants: In this predefined analysis using data from the POETYK PSO-1 multicenter, randomized, double-blind, placebo-controlled phase 3 clinical trial, conducted from August 7, 2018, to September 2, 2020, 666 adults with moderate to severe plaque psoriasis completed the PSSD daily throughout the trial. Meaningful change thresholds were derived by anchoring mean PSSD score change from baseline to week 16 to category improvements on the Patient Global Impression of Change (PGI-C) and the Patient Global Impression of Severity (PGI-S). Interventions: Deucravacitinib, 6 mg, once daily; placebo; or apremilast, 30 mg, twice daily. Main Outcome and Measures: The main outcome was score change from baseline to week 16 on the PSSD, anchored to the PGI-C and PGI-S. Results: The trial included 666 patients (mean [SD] age, 46.1 [13.4] years; 453 men [68.0%]). Three thresholds were identified using an analysis set of 609 patients. Score improvement of at least 15 points from baseline reflected meaningful within-patient change anchored to the PGI-C. Score improvements of 25 points were supported by both the PGI-C and the PGI-S, while a 30-point score change identified patients with greater improvements in their psoriasis symptoms and signs. Conclusions and Relevance: This analysis suggests that PSSD score improvements of 15, 25, or 30 points represent increasing improvements in disease burden that are meaningful to patients with psoriasis.


Assuntos
Psoríase , Talidomida , Talidomida/análogos & derivados , Adulto , Masculino , Humanos , Pessoa de Meia-Idade , Índice de Gravidade de Doença , Talidomida/uso terapêutico , Psoríase/diagnóstico , Psoríase/tratamento farmacológico , Método Duplo-Cego , Resultado do Tratamento
4.
Dermatol Ther (Heidelb) ; 12(2): 495-510, 2022 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-35025062

RESUMO

INTRODUCTION: Deucravacitinib is an oral, selective tyrosine kinase 2 inhibitor that demonstrated therapeutic benefit in a Phase 2 clinical trial of adults with moderate to severe plaque psoriasis. This analysis was designed to evaluate the effect of deucravacitinib on additional clinical and quality-of-life (QoL) outcomes and assess the relationship between these outcomes in adults with psoriasis. METHODS: Post-hoc analysis of a 12-week Phase 2 trial was conducted for the three most efficacious dosage groups (3 mg twice daily, 6 mg twice daily, 12 mg once daily) and placebo. Investigator assessments for efficacy included Psoriasis Area and Severity Index (PASI), body surface area (BSA) involvement, and static Physician's Global Assessment; QoL was assessed using the Dermatology Life Quality Index (DLQI). Treatment responses and their associations were evaluated over time. RESULTS: Deucravacitinib elicited improvement versus placebo as early as Week 4 for most efficacy measures (including changes in absolute PASI and BSA), with efficacy trends observed from Week 2 to Week 12. Improvements in QoL, assessed by achievement of a DLQI overall score of 0/1 (no effect at all on patient's life), followed a pattern similar to deucravacitinib-related clinical outcomes over 12 weeks. Overall, patients with greater improvements in psoriasis-related clinical signs and symptoms also reported greater improvement in QoL. However, complete skin clearance was not required for achieving DLQI 0/1. CONCLUSION: Deucravacitinib treatment produced early response and similar trends in improvements across multiple efficacy assessments and QoL in moderate to severe plaque psoriasis. Deucravacitinib has the potential to become a promising new oral therapy for this condition. TRIAL REGISTRATION: ClinicalTrials.gov identifier; NCT02931838.


Psoriasis is a skin disease that affects up to 2% of the population. In psoriasis, red, scaly lesions develop on the skin driven by an aberrant immune response. Psoriasis impacts not only physical and mental health but also quality of life (QoL). Deucravacitinib is being investigated as a treatment for psoriasis. We performed a Phase 2 dose-ranging, placebo-controlled, 12-week study of deucravacitinib in adults with moderate to severe psoriasis. Patients in the USA, Australia, Canada, Germany, Japan, Latvia, Mexico, and Poland participated. The study showed that oral treatment with deucravacitinib was effective using a disease severity score (percentage of patients with ≥ 75% reduction from baseline in Psoriasis Area and Severity Index score) at Week 12­placebo 7% and deucravacitinib 67%­75% for the three highest dosages­and was generally well tolerated. We further analyzed the association between efficacy and a QoL measure, the Dermatology Life Quality Index (DLQI), in patients who received placebo or the most effective dosages of deucravacitinib (≥ 3 mg twice daily). Deucravacitinib was effective at the three dosage levels tested. Skin improvement occurred early during treatment and was mirrored by improvements in DLQI score during the 12 weeks of treatment. Although some patients did not have complete clearance of their psoriasis, a large percentage of those patients still achieved considerable improvement in QoL as measured by achieving a DLQI score of 0/1 (i.e., no effect at all on the patient's QoL).

5.
Biochemistry ; 59(48): 4523-4532, 2020 12 08.
Artigo em Inglês | MEDLINE | ID: mdl-33205945

RESUMO

We demonstrate here that the α subunit C-terminal domain of Escherichia coli RNA polymerase (αCTD) recognizes the upstream promoter (UP) DNA element via its characteristic minor groove shape and electrostatic potential. In two compositionally distinct crystallized assemblies, a pair of αCTD subunits bind in tandem to the UP element consensus A-tract that is 6 bp in length (A6-tract), each with their arginine 265 guanidinium group inserted into the minor groove. The A6-tract minor groove is significantly narrowed in these crystal structures, as well as in computationally predicted structures of free and bound DNA duplexes derived by Monte Carlo and molecular dynamics simulations, respectively. The negative electrostatic potential of free A6-tract DNA is substantially enhanced compared to that of generic DNA. Shortening the A-tract by 1 bp is shown to "knock out" binding of the second αCTD through widening of the minor groove. Furthermore, in computationally derived structures with arginine 265 mutated to alanine in either αCTD, either with or without the "knockout" DNA mutation, contact with the DNA is perturbed, highlighting the importance of arginine 265 in achieving αCTD-DNA binding. These results demonstrate that the importance of the DNA shape in sequence-dependent recognition of DNA by RNA polymerase is comparable to that of certain transcription factors.


Assuntos
DNA Bacteriano/química , DNA Bacteriano/metabolismo , RNA Polimerases Dirigidas por DNA/química , RNA Polimerases Dirigidas por DNA/metabolismo , Proteínas de Escherichia coli/química , Proteínas de Escherichia coli/metabolismo , Sítios de Ligação , Cristalografia por Raios X , Proteína Receptora de AMP Cíclico/química , Proteína Receptora de AMP Cíclico/genética , Proteína Receptora de AMP Cíclico/metabolismo , DNA Bacteriano/genética , RNA Polimerases Dirigidas por DNA/genética , Escherichia coli/genética , Escherichia coli/metabolismo , Proteínas de Escherichia coli/genética , Técnicas de Inativação de Genes , Genes Bacterianos , Modelos Moleculares , Mutação , Conformação de Ácido Nucleico , Regiões Promotoras Genéticas , Domínios Proteicos , Eletricidade Estática
6.
Hepatol Commun ; 2(4): 354-363, 2018 04.
Artigo em Inglês | MEDLINE | ID: mdl-29619415

RESUMO

We report the findings of an early access program providing treatment for chronic hepatitis C virus infection (any genotype) with daclatasvir and sofosbuvir with/without ribavirin to patients with Child-Pugh class C cirrhosis or prior liver transplant recipients with recurrent hepatitis C virus infection and advanced fibrosis/cirrhosis. Patients had <12-month life expectancies per the local investigator. Patients received daclatasvir 60 mg and sofosbuvir 400 mg once daily, with/without ribavirin, for 24 weeks. Sustained virologic response (SVR) at posttreatment week 12 (SVR12) was measured. Assessments adhered to local standards. One patient (prior Child-Pugh class C who improved to class B) enrolled by exemption was included in the overall data but not the class C cohort efficacy/safety data. Of the 77 treated patients, including 62 liver transplant recipients (genotype 1, n = 43, 69%; genotype 3, n = 16, 26%) and 14 patients with Child-Pugh class C cirrhosis (genotype 1, n = 4, 29%; genotype 3, n = 10, 71%), 63 (82%) completed treatment. SVR12 rates by modified intention-to-treat analysis (excluding nonvirologic failures lost to follow-up and withdrawal [consent/no reason]) in the overall, liver transplant, and Child-Pugh class C cohorts were 84% (n = 64/76), 90% (n = 56/62), and 62% (n = 8/13), respectively. Rates increased to 96% (n = 64/67), 97% (n = 56/58), and 89% (n = 8/9), respectively, in patients with available virologic data (including early discontinuations); 22/23 patients with genotype 3 (96%) achieved SVR12. Single cases of virologic nonresponse and relapse (both in liver transplant recipients with genotype 1) and viral breakthrough (Child-Pugh class C; genotype 3) occurred. Six patients died, 10 had adverse events leading to discontinuation, and 30 experienced serious adverse events. Conclusion: Daclatasvir plus sofosbuvir, with/without ribavirin, provided high SVR12 rates and was generally well tolerated in patients with life-threatening disease and high unmet needs. (Hepatology Communications 2018;2:354-363).

7.
AIDS ; 31(17): 2337-2344, 2017 11 13.
Artigo em Inglês | MEDLINE | ID: mdl-28832406

RESUMO

OBJECTIVES: Some studies suggest that bioavailable 25-dihydroxyvitamin D [25-(OH)D] is more accurate than total 25-(OH)D as an assessment of vitamin D (VitD) status in black individuals. We hypothesized that increases in bioavailable 25-(OH)D would correlate better with improvement in bone outcomes among black HIV-infected adults. DESIGN: This is a secondary analysis of AIDS Clinical Trials Group A5280, a randomized, double-blind study of VitD3 and calcium supplementation in HIV-infected participants initiating antiretroviral therapy. METHODS: Effect of VitD/calcium on total and calculated bioavailable 25-(OH)D, parathyroid hormone, bone turnover markers, and bone mineral density in black and nonblack participants were evaluated at 48 weeks. Wilcoxon signed-rank tests and Wilcoxon rank sum tests assessed within and between-race differences. RESULTS: Of 165 participants enrolled, 129 (40 black and 89 nonblack) had complete data. At baseline, black participants had lower total 25-(OH)D [median (Q1,Q3) 22.6 (15.8, 26.9) vs. 31.1 (23.1, 38.8) ng/ml, P < 0.001] but higher bioavailable 25-(OH)D [2.9 (1.5, 5.2) vs. 2.0 (1.5, 3.0) ng/ml, P = 0.022] than nonblack participants. After 48 weeks of VitD/calcium supplementation, bioavailable 25-(OH)D increased more in black than nonblack participants, but there were no between-race differences change in bone turnover markers or bone mineral density. The associations between increases in 25-(OH)D levels and change in bone outcomes appeared similar for both total and bioavailable 25-(OH)D. CONCLUSION: Baseline and change in bioavailable 25-(OH)D were higher among black adults initiating antiretroviral therapy with VitD/calcium; however, associations between 25-(OH)D and bone outcomes appeared similar for total and bioavailable 25-(OH)D. The assessment of total 25-(OH)D may be sufficient for evaluation of VitD status in black HIV-infected individuals. TRIAL REGISTRATION NUMBER: NCT01403051.


Assuntos
População Negra , Cálcio/administração & dosagem , Infecções por HIV/complicações , Osteoporose/prevenção & controle , Vitamina D/administração & dosagem , Vitamina D/farmacocinética , Adulto , Disponibilidade Biológica , Densidade Óssea , Remodelação Óssea , Método Duplo-Cego , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Hormônio Paratireóideo/sangue , Resultado do Tratamento
8.
Ann Intern Med ; 162(12): 815-24, 2015 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-26075752

RESUMO

BACKGROUND: Antiretroviral therapy initiation for HIV-1 infection is associated with 2% to 6% loss of bone mineral density (BMD). OBJECTIVE: To evaluate the effect of vitamin D3 plus calcium supplementation on bone loss associated with antiretroviral therapy initiation. DESIGN: 48-week prospective, randomized, double-blind, placebo-controlled study. (ClinicalTrials.gov: NCT01403051). SETTING: 39 AIDS Clinical Trials Group units. PATIENTS: Adults with antiretroviral therapy-naive HIV. MEASUREMENTS: BMD by dual-energy x-ray absorptiometry, 25-hydroxyvitamin D levels, and other laboratory assessments. RESULTS: 165 eligible patients were randomly assigned (79 received vitamin D3 plus calcium and 86 received placebo). The study groups were well-balanced at baseline: 90% were men, 33% were non-Hispanic black, and the median CD4 count was 0.341 × 109 cells/L. At 48 weeks, the percentage of decline in total hip BMD was smaller in the vitamin D3 plus calcium group than in the placebo group: Medians were -1.36% (interquartile range [IQR], -3.43% to 0.50%) and -3.22% (IQR, -5.56% to -0.88%), respectively (P = 0.004). Similar results were seen at the lumbar spine. At 48 weeks, 90% of patients achieved HIV-1 RNA levels less than 50 copies/mL. Levels of 25-hydroxyvitamin D3 increased with vitamin D3 plus calcium but not with placebo: Median change was 61.2 nmol/L (IQR, 36.4 to 94.3) versus 1.7 nmol/L (IQR, -13.2 to 10.7) (P < 0.001). Overall, 103 patients (62%) reported 1 or more adverse event, with similar distribution between groups; no cases of hypercalcemia and 1 case of nephrolithiasis were reported in the placebo group. LIMITATION: No international sites were included, and follow-up was only 48 weeks. CONCLUSION: Vitamin D3 plus calcium supplementation mitigates the BMD loss seen with initiation of efavirenz/emtricitabine/tenofovir disoproxil fumarate.


Assuntos
Antirretrovirais/efeitos adversos , Conservadores da Densidade Óssea/uso terapêutico , Calcifediol/uso terapêutico , Carbonato de Cálcio/uso terapêutico , Suplementos Nutricionais , Osteoporose/prevenção & controle , Absorciometria de Fóton , Adulto , Biomarcadores/sangue , Densidade Óssea/efeitos dos fármacos , Reabsorção Óssea , Calcifediol/efeitos adversos , Calcifediol/sangue , Carbonato de Cálcio/efeitos adversos , Carbonato de Cálcio/sangue , Método Duplo-Cego , Feminino , Infecções por HIV/tratamento farmacológico , HIV-1 , Humanos , Masculino , Pessoa de Meia-Idade , Osteoporose/induzido quimicamente , Hormônio Paratireóideo/sangue , Estudos Prospectivos
9.
J Int AIDS Soc ; 17: 19214, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-25192857

RESUMO

OBJECTIVE: To assess the potential association of selected antiretrovirals (ARVs), including efavirenz, with suicidality. DESIGN: Retrospective analysis of the Food and Drug Administration Adverse Event Reporting System (FAERS), by performing a Multi-Item Gamma Poisson Shrinker (MGPS) disproportionality analysis. METHODS: MGPS disproportionality analysis, a technique to identify associations between drugs and adverse events, was performed using cumulative data from the FAERS database collected up to August 2012. This method yields an Empirical Bayesian Geometric Mean score and corresponding 90% confidence interval (EB05, EB95). EB05 scores ≥ 2 were pre-defined as a signal for a potential drug-event association. The FAERS database includes spontaneous adverse-event reports from consumers and healthcare professionals. All FAERS reports of suicidality (including suicidal ideation, suicide attempt and completed suicide or a composite of these) in patients taking efavirenz (as single agent or in fixed-dose combination), atazanavir, darunavir, etravirine, nevirapine and raltegravir were identified. A number of parallel analyses were performed to assess the validity of the methodology: fluoxetine and sertraline, antidepressants with a known association with suicidality, and raltegravir, an ARV with rhabdomyolysis and myopathy listed as "uncommon" events in the US-prescribing information. RESULTS: A total of 29,856 adverse event reports were identified among patients receiving efavirenz, atazanavir, darunavir, etravirine, nevirapine and raltegravir, of which 457 were reports of suicidality events. EB05 scores observed for the composite suicidality term for efavirenz (EB05=0.796), and other ARVs (EB05=0.279-0.368), were below the pre-defined threshold. Fluoxetine and sertraline gave EB05 scores for suicidality >2. Raltegravir gave EB05 scores >2 for myopathy and rhabdomyolysis. CONCLUSIONS: The pre-determined threshold for signals for suicidality, including suicidal ideation, suicide attempt, completed suicide and a composite suicidality endpoint, was not exceeded for efavirenz and other ARVs in this analysis. Efavirenz has been associated with suicidality in clinical trials. Further studies that adjust for confounding factors are needed to better understand any potential association with ARVs and suicidality.


Assuntos
Antirretrovirais/efeitos adversos , Antirretrovirais/uso terapêutico , Benzoxazinas/efeitos adversos , Benzoxazinas/uso terapêutico , Infecções por HIV/tratamento farmacológico , Infecções por HIV/fisiopatologia , Suicídio/estatística & dados numéricos , Alcinos , Ciclopropanos , Humanos , Vigilância de Produtos Comercializados , Estados Unidos/epidemiologia
10.
J Mol Biol ; 386(4): 1054-65, 2009 Mar 06.
Artigo em Inglês | MEDLINE | ID: mdl-19244617

RESUMO

One obstacle to achieving complete understanding of the principles underlying sequence-dependent recognition of DNA is the paucity of structural data for DNA recognition sequences in their free (unbound) state. Here, we carried out crystallization screening of 50 DNA duplexes containing cognate protein binding sites and obtained new crystal structures of free DNA binding sites for three distinct modes of DNA recognition: anti-parallel beta strands (MetR), helix-turn-helix motif + hinge helices (PurR), and zinc fingers (Zif268). Structural changes between free and protein-bound DNA are manifested differently in each case. The new DNA structures reveal that distinctive sequence-dependent DNA geometry dominates recognition by MetR, protein-induced bending of DNA dictates recognition by PurR, and deformability of DNA along the A-B continuum is important in recognition by Zif268. Together, our findings show that crystal structures of free DNA binding sites provide new information about the nature of protein-DNA interactions and thus lend insights towards a structural code for DNA recognition.


Assuntos
DNA/metabolismo , Proteínas/metabolismo , Proteínas de Bactérias/química , Proteínas de Bactérias/metabolismo , Pareamento de Bases , Sequência de Bases , Sítios de Ligação , Cristalografia por Raios X , DNA/química , Proteína 1 de Resposta de Crescimento Precoce/química , Proteína 1 de Resposta de Crescimento Precoce/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Ligação Proteica , Proteínas/química , Sequências Reguladoras de Ácido Nucleico/genética , Proteínas Repressoras/química , Proteínas Repressoras/metabolismo , Dedos de Zinco
11.
J Mol Biol ; 357(1): 173-83, 2006 Mar 17.
Artigo em Inglês | MEDLINE | ID: mdl-16427082

RESUMO

The catabolite activator protein (CAP) bends DNA in the CAP-DNA complex, typically introducing a sharp DNA kink, with a roll angle of approximately 40 degrees and a twist angle of approximately 20 degrees, between positions 6 and 7 of the DNA half-site, 5'-A1A2A3T4G5T6G7A8T9C10T11 -3' ("primary kink"). In previous work, we showed that CAP recognizes the nucleotide immediately 5' to the primary-kink site, T6, through an "indirect-readout" mechanism involving sequence effects on energetics of primary-kink formation. Here, to understand further this example of indirect readout, we have determined crystal structures of CAP-DNA complexes containing each possible nucleotide at position 6. The structures show that CAP can introduce a DNA kink at the primary-kink site with any nucleotide at position 6. The DNA kink is sharp with the consensus pyrimidine-purine step T6G7 and the non-consensus pyrimidine-purine step C6G7 (roll angles of approximately 42 degrees, twist angles of approximately 16 degrees ), but is much less sharp with the non-consensus purine-purine steps A6G7 and G6G7 (roll angles of approximately 20 degrees, twist angles of approximately 17 degrees). We infer that CAP discriminates between consensus and non-consensus pyrimidine-purine steps at positions 6-7 solely based on differences in the energetics of DNA deformation, but that CAP discriminates between the consensus pyrimidine-purine step and non-consensus purine-purine steps at positions 6-7 both based on differences in the energetics of DNA deformation and based on qualitative differences in DNA deformation. The structures further show that CAP can achieve a similar, approximately 46 degrees per DNA half-site, overall DNA bend through a sharp DNA kink, a less sharp DNA kink, or a smooth DNA bend. Analysis of these and other crystal structures of CAP-DNA complexes indicates that there is a large, approximately 28 degrees per DNA half-site, out-of-plane component of CAP-induced DNA bending in structures not constrained by end-to-end DNA lattice interactions and that lattice contacts involving CAP tend to involve residues in or near biologically functional surfaces.


Assuntos
Proteína Receptora de AMP Cíclico/química , DNA/química , Conformação de Ácido Nucleico , Estrutura Terciária de Proteína , Purinas/química , Pirimidinas/química , Análise de Sequência de DNA , Sequência de Bases , Proteína Receptora de AMP Cíclico/genética , Proteína Receptora de AMP Cíclico/metabolismo , DNA/metabolismo , Escherichia coli/metabolismo , Substâncias Macromoleculares , Modelos Moleculares , Dados de Sequência Molecular
12.
Cell ; 122(4): 541-52, 2005 Aug 26.
Artigo em Inglês | MEDLINE | ID: mdl-16122422

RESUMO

We define the target, mechanism, and structural basis of inhibition of bacterial RNA polymerase (RNAP) by the tetramic acid antibiotic streptolydigin (Stl). Stl binds to a site adjacent to but not overlapping the RNAP active center and stabilizes an RNAP-active-center conformational state with a straight-bridge helix. The results provide direct support for the proposals that alternative straight-bridge-helix and bent-bridge-helix RNAP-active-center conformations exist and that cycling between straight-bridge-helix and bent-bridge-helix RNAP-active-center conformations is required for RNAP function. The results set bounds on models for RNAP function and suggest strategies for design of novel antibacterial agents.


Assuntos
Aminoglicosídeos/farmacologia , Bactérias/enzimologia , Bactérias/genética , RNA Polimerases Dirigidas por DNA/antagonistas & inibidores , RNA Polimerases Dirigidas por DNA/metabolismo , RNA Mensageiro/biossíntese , Aminoglicosídeos/química , Sítios de Ligação/efeitos dos fármacos , Sítios de Ligação/fisiologia , RNA Polimerases Dirigidas por DNA/química , Retroalimentação Fisiológica/fisiologia , Modelos Moleculares , Estrutura Molecular , Estrutura Secundária de Proteína/efeitos dos fármacos , Estrutura Secundária de Proteína/genética
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