title: DNA sequence requirements for the activation of 434 P(RM) transcription by 434 repressor.
abstract: A dimer of the 434 repressor bound at O(R)2 activated transcription initiation from P(RM) by contacting RNA polymerase. Although DNA-binding site mutations at either end of O(R)2 decreased the ability of the repressor to activate P(RM) transcription, mutations proximal to the promoter had a greater effect on transcription activation. Orienting a repressor subunit bearing the altered specificity Gln-28 --> Ala mutation to the halfsite of O(R)2 proximal to the P(RM) promoter decreased the repressor's ability to activate transcription initiation at 434 P(RM) to a much greater extent than if this subunit was placed in the O(R)2 half-site distal to P(RM). In addition to showing that the downstream (promoter proximal) subunit of the O(R)2-bound 434 repressor functions in activating 434 P(RM), the results indicated that DNA sequence-dependent conformational changes alter the efficiency with which the repressor activates P(RM) transcription. These unexpected findings highlight the importance of the structure of the repressor-DNA interface in activating transcription from P(RM).
authors.affiliation: Department of Biological Sciences, State University of New York at Buffalo, Buffalo, New York 14260-1300, USA.
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: G B
authors.initials: GB
authors.lastname: Koudelka
mesh_terms: D019943:Amino Acid Substitution; D001483:Base Sequence; D001665:Binding Sites; D001667:Binding, Competitive; D004279:DNA, Viral / Q000235:genetics / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D019281:Dimerization; D015967:Gene Expression Regulation, Viral; D008969:Molecular Sequence Data; D009154:Mutation; D011485:Protein Binding; D021122:Protein Subunits; D012097:Repressor Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D015533:Transcriptional Activation; D014764:Viral Proteins / Q000235:genetics*
chemical_list: C063367:434-repressor protein, Bacteriophage 434; D004279:DNA, Viral; D021122:Protein Subunits; D012097:Repressor Proteins; D014764:Viral Proteins; D012321:DNA-Directed RNA Polymerases