View source for 1tkv


==Solution Structure of T4 AsiA Dimer==
<StructureSection load='1tkv' size='340' side='right'caption='[[1tkv]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1tkv]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_virus_T4 Escherichia virus T4]. This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=1ka3 1ka3]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1TKV OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1TKV FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR</td></tr>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1tkv FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1tkv OCA], [https://pdbe.org/1tkv PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1tkv RCSB], [https://www.ebi.ac.uk/pdbsum/1tkv PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1tkv ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/ASIA_BPT4 ASIA_BPT4] Transcriptional inhibitor. Inhibits sigma 70-directed transcription by weakening its interaction with the core of the host's RNA polymerase. This allows Gp55 to successfully compete for the core enzyme. Plays an important role during the prereplicative period of phage T4 development.<ref>PMID:8021178</ref> <ref>PMID:15257291</ref> 
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/tk/1tkv_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/main_output.php?pdb_ID=1tkv ConSurf].
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== Publication Abstract from PubMed ==
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.

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<ref>PMID:11742991</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia virus T4]]
[[Category: Large Structures]]
[[Category: Cadene M]]
[[Category: Demeler B]]
[[Category: Lambert LJ]]
[[Category: Schirf V]]
[[Category: Werner MH]]