RESUMO
A series of transition-state analog inhibitors of the D-glutamic acid-adding enzyme (MurD) of bacterial peptidoglycan biosynthesis has been synthesized and evaluated for inhibition of the E. coli enzyme.
Assuntos
Parede Celular/enzimologia , Escherichia coli/enzimologia , Peptídeo Sintases/antagonistas & inibidores , Estrutura Molecular , Compostos Organofosforados/química , Peptídeo Sintases/químicaRESUMO
By selective attachment of a DNA cleavage agent to specific residues in the yeast TATA box binding protein (yTBP), we demonstrate that, in solution, yTBP binds to the TATA boxes of both the adenovirus major late promoter and the yeast CYC1 promoter with only a modest preference in orientation and binds well to several overlapping binding sites. The general factors TFIIA and TFIIB each increase the rotational and translational selectivity of yTBP but are not sufficient, at least individually, to confer a unique polarity to the preinitiation complex. We conclude that TBP alone cannot define the productive orientation of general factor assembly on a promoter.
Assuntos
Proteínas de Ligação a DNA/metabolismo , TATA Box , Fatores de Transcrição/metabolismo , Adenoviridae/genética , Alquilação , Sequência de Bases , Sítios de Ligação/genética , DNA Fúngico/química , DNA Fúngico/genética , DNA Fúngico/metabolismo , Proteínas de Ligação a DNA/química , Proteínas de Ligação a DNA/genética , Modelos Moleculares , Dados de Sequência Molecular , Conformação de Ácido Nucleico , Regiões Promotoras Genéticas , Ligação Proteica , Conformação Proteica , Saccharomyces cerevisiae/genética , Saccharomyces cerevisiae/metabolismo , Proteína de Ligação a TATA-Box , Fatores de Transcrição/química , Fatores de Transcrição/genéticaRESUMO
At least three hundred million people worldwide are infected with the hepatitis B virus (HBV), and epidemiological studies show a clear correlation between chronic HBV infection and the development of hepatocellular carcinoma. HBV encodes a protein, pX, which abducts the cellular transcriptional machinery in several ways including direct interactions with bZIP transcription factors. These interactions increase the DNA affinities of target bZIP proteins in a DNA sequence-dependent manner. Here we use a series of bZIP peptide models to explore the mechanism by which pX interacts with bZIP proteins. Our results suggest that pX increases bZIP.DNA stability by increasing the stability of the bZIP dimer as well as the affinity of the dimer for DNA. Additional experiments provide evidence for a mechanism in which pX recognizes the composite structure of the peptide.DNA complex, not simply the primary peptide sequence. These experiments provide a framework for understanding how pX alters the patterns of transcription within the nucleus. The similarities between the mechanism proposed for pX and the mechanism previously proposed for the human T-cell leukemia virus protein Tax are discussed.
