The C-terminal domain of the Escherichia coli RNA polymerase alpha subunit plays a role in the CI-dependent activation of the bacteriophage lambda pM promoter.
The bacteriophage lambda p(M) promoter is required for maintenance of the lambda prophage in Escherichia coli, as it facilitates transcription of the cI gene, encoding the lambda repressor (CI). CI levels are maintained through a transcriptional feedback mechanism whereby CI can serve as an activator or a repressor of p(M). CI activates p(M) through cooperative binding to the O(R)1 and O(R)2 sites within the O(R) operator, with the O(R)2-bound CI dimer making contact with domain 4 of the RNA polymerase sigma subunit (sigma(4)). Here we demonstrate that the 261 and 287 determinants of the C-terminal domain of the RNA polymerase alpha subunit (alphaCTD), as well as the DNA-binding determinant, are important for CI-dependent activation of p(M). We also show that the location of alphaCTD at the p(M) promoter changes in the presence of CI. Thus, in the absence of CI, one alphaCTD is located on the DNA at position -44 relative to the transcription start site, whereas in the presence of CI, alphaCTD is located at position -54, between the CI-binding sites at O(R)1 and O(R)2. These results suggest that contacts between CI and both alphaCTD and sigma are required for efficient CI-dependent activation of p(M).
Kedzierska
Barbara
B
Department of Molecular Biology, University of Gdansk, Kladki 24, Gdansk, Poland.
Szambowska
Anna
A
Herman-Antosiewicz
Anna
A
Lee
David J
DJ
Busby
Stephen J W
SJ
Wegrzyn
Grzegorz
G
Thomas
Mark S
MS
D019943:Amino Acid Substitution; D010582:Bacteriophage lambda / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000378:metabolism*; D012321:DNA-Directed RNA Polymerases / Q000737:chemistry* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000378:metabolism; D015967:Gene Expression Regulation, Viral; D008957:Models, Genetic; D011401:Promoter Regions, Genetic; D017434:Protein Structure, Tertiary; D012097:Repressor Proteins / Q000378:metabolism*; D015533:Transcriptional Activation; D014764:Viral Proteins / Q000378:metabolism*; D054334:Viral Regulatory and Accessory Proteins
D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; D014764:Viral Proteins; D054334:Viral Regulatory and Accessory Proteins; C016649:phage repressor proteins; D012321:DNA-Directed RNA Polymerases; C113275:RNA polymerase alpha subunit