1tkv
From Proteopedia
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| Gene: | ASIA (Bacteriophage T4) | ||||||
| Coordinates: | save as pdb, mmCIF, xml | ||||||
Solution Structure of T4 AsiA Dimer
Overview
The bacteriophage T4 AsiA protein is a multifunctional protein that simultaneously acts as both a repressor and activator of gene expression during the phage life cycle. These dual roles with opposing transcriptional consequences are achieved by modification of the host RNA polymerase in which AsiA binds to conserved region 4 (SR4) of sigma(70), altering the pathway of promoter selection by the holoenzyme. The mechanism by which AsiA flips this genetic switch has now been revealed, in part, from the three-dimensional structure of AsiA and the elucidation of its interaction with SR4. The structure of AsiA is that of a novel homodimer in which each monomer is constructed as a seven-helix bundle arranged in four overlapping helix-loop-helix elements. Identification of the protein interfaces for both the AsiA homodimer and the AsiA-sigma(70) complex reveals that these interfaces are coincident. Thus, the AsiA interaction with sigma(70) necessitates that the AsiA homodimer dissociate to form an AsiA-SR4 heterodimer, exchanging one protein subunit for another to alter promoter choice by RNA polymerase.
About this Structure
1TKV is a Single protein structure of sequence from Bacteriophage t4. This structure supersedes the now removed PDB entry 1KA3. Full crystallographic information is available from OCA.
Reference
Flipping a genetic switch by subunit exchange., Lambert LJ, Schirf V, Demeler B, Cadene M, Werner MH, EMBO J. 2001 Dec 17;20(24):7149-59. PMID:11742991
Page seeded by OCA on Thu Mar 20 14:19:43 2008
