1TKV

Solution Structure of T4 AsiA Dimer

Replaces:  1KA3

Summary for 1TKV

• Entry DOI: 10.2210/pdb1tkv/pdb
• Descriptor: 10 kDa anti-sigma factor (1 entity in total)
• Functional Keywords: anti-sigma, homodimer, transcription
• Biological source: Enterobacteria phage T4
• Total number of polymer chains: 2
• Total formula weight: 21208.02

Authors

Lambert, L.J.,Schirf, V.,Demeler, B.,Cadene, M.,Werner, M.H. (deposition date: 2004-06-09, release date: 2004-06-22, Last modification date: 2024-05-22)

Primary citation

Lambert, L.J.,Schirf, V.,Demeler, B.,Cadene, M.,Werner, M.H.
Flipping a genetic switch by subunit exchange
Embo J., 20:7149-7159, 2001

PubMed Abstract: 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.

PubMed: 11742991
DOI: 10.1093/emboj/20.24.7149

Experimental method

SOLUTION NMR