PMID:9324270
| Citation |
Yang, J, Murakami, K, Camakaris, H, Fujita, N, Ishihama, A and Pittard, AJ (1997) Amino acid residues in the alpha-subunit C-terminal domain of Escherichia coli RNA polymerase involved in activation of transcription from the mtr promoter. J. Bacteriol. 179:6187-91 |
|---|---|
| Abstract |
To examine the role of the amino acid residues (between positions 258 and 275 and positions 297 and 298) of the alpha-subunit of RNA polymerase in TyrR-mediated activation of the mtr promoter, we have carried out in vitro transcription experiments using a set of mutant RNA polymerases with a supercoiled mtr template. Decreases in factor-independent transcription in vitro by mutant RNA polymerases L262A, R265A, and K297A suggested the presence of a possible UP element associated with the mtr promoter. Mutational studies have revealed that an AT-rich sequence centered at -41 of the mtr promoter (SeqA) functions like an UP element. In vivo and in vitro analyses using a mutant mtr promoter carrying a disrupted putative UP element showed that this AT-rich sequence is responsible for interactions with the alpha-subunit which influence transcription in the absence of TyrR protein. However, the putative UP element is not needed for activator-dependent activation of the mtr promoter by TyrR and phenylalanine. The results from in vitro studies indicated that the alpha-subunit residues leucine-262, arginine-265, and lysine-297 are critical for interaction with the putative UP element of the mtr promoter and play major roles in TyrR-dependent transcription activation. The residues at positions 258, 260, 261, 268, and 270 also play important roles in TyrR-dependent activation. Other residues, at positions 259, 263, 264, 266, 269, 271, 273, 275, and 298, appear to play less significant roles or no role in activation of mtr transcription. |
| Links | |
| Keywords |
Amino Acid Transport Systems; Amino Acid Transport Systems, Neutral; Bacterial Proteins/genetics; Bacterial Proteins/pharmacology; Base Sequence; DNA-Binding Proteins/pharmacology; DNA-Directed RNA Polymerases/chemistry; DNA-Directed RNA Polymerases/metabolism; Escherichia coli/enzymology; Escherichia coli/genetics; Escherichia coli Proteins; Gene Expression Regulation, Bacterial; Membrane Proteins/genetics; Membrane Transport Proteins/genetics; Molecular Sequence Data; Mutation; Phenylalanine/pharmacology; Promoter Regions, Genetic; Repressor Proteins/metabolism; Repressor Proteins/pharmacology; Templates, Genetic; Transcriptional Activation |
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