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J. Bacteriol., Dec 1995, 6740-6744, Vol 177, No. 23
K Tao, C Zou, N Fujita and A Ishihama
The Escherichia coli OxyR protein requires the C-terminal contact site I
region of the RNA polymerase alpha subunit for cooperative interaction with
and transcription activation at OxyR-dependent promoters, suggesting direct
protein-protein contact between OxyR and the C-terminal region of the alpha
subunit. To determine the precise location of the OxyR protein contact
site(s) in this region, we carried out mutational analysis of the 3' half
of E. coli rpoA, the gene encoding the alpha subunit of RNA polymerase. We
isolated a number of rpoA mutants defective in oxyR-dependent transcription
activation at the E. coli katG promoter. Nucleotide sequence analysis of
the rpoA gene from these mutants revealed that the mutations showing clear
phenotypes are all clustered at two narrow regions (amino acid residues 265
to 269 and 293 to 300) within the C terminus of the alpha subunit.
Reconstituted RNA polymerases containing the mutant alpha subunits were
unable to respond to transcription activation in vitro at the katG, ahpC,
and oxyX promoters by OxyR. These results suggest that these two regions
comprise the contact surfaces on the alpha subunit for OxyR.
Copyright © 1995, American Society for Microbiology
Mapping of the OxyR protein contact site in the C-terminal region of RNA polymerase alpha subunit
Radioisotope Center, University of Tokyo, Japan.
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