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The Interaction between the AsiA Protein of Bacteriophage T4 and the Ï70 Subunit of Escherichia coli RNA Polymerase
The AsiA protein of bacteriophage T4 binds to the Ï 70 subunit of Escherichia coli RNA polymerase and plays a dual regulatory role during T4 development: (i) inhibition of host and phage early transcription, and (ii) coactivation of phage middle-mode transcription, which also requires the T4 DNA bi...
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Published in: | The Journal of biological chemistry 1997-10, Vol.272 (43), p.27435 |
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Main Authors: | , , , , |
Format: | Article |
Language: | English |
Online Access: | Get full text |
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Summary: | The AsiA protein of bacteriophage T4 binds to the Ï 70 subunit of Escherichia coli RNA polymerase and plays a dual regulatory role during T4 development: (i) inhibition of host and phage early transcription,
and (ii) coactivation of phage middle-mode transcription, which also requires the T4 DNA binding transcriptional activator,
MotA. We report that the interaction between AsiA and Ï 70 occurs with a 1:1 stoichiometry. When preincubated with RNA polymerase, AsiA is a potent inhibitor of open complex formation
at the lac UV5 promoter, whereas it does not perturb preformed open or intermediate promoter complexes. DNase I footprinting and electrophoretic
mobility shift analyses of RNA polymerase-DNA complexes formed at the T4 early promoter P15.0 show that AsiA blocks the initial
RNA polymerase binding step that leads to the formation of specific closed promoter complexes. A contrasting result is obtained
on the T4 middle promoter PrIIB2, where AsiA stimulates the formation of both closed complexes and open complexes. Therefore,
we propose that AsiA modulates initial DNA binding by the RNA polymerase, switching promoter usage at the level of closed
complex formation. |
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ISSN: | 0021-9258 1083-351X |
DOI: | 10.1074/jbc.272.43.27435 |