View source for 4icg


==N-terminal dimerization domain of H-NS in complex with Hha (Salmonella Typhimurium)==
<StructureSection load='4icg' size='340' side='right'caption='[[4icg]], [[Resolution|resolution]] 2.92&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[4icg]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Salmonella_enterica_subsp._enterica_serovar_Typhimurium_str._LT2 Salmonella enterica subsp. enterica serovar Typhimurium str. LT2]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=4ICG OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=4ICG FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 2.9217&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=MSE:SELENOMETHIONINE'>MSE</scene></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=4icg FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=4icg OCA], [https://pdbe.org/4icg PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=4icg RCSB], [https://www.ebi.ac.uk/pdbsum/4icg PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=4icg ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/HNS_SALTY HNS_SALTY] H-NS binds tightly to ds-DNA, increases its thermal stability and inhibits transcription. It also binds to ss-DNA and RNA but with a much lower affinity. H-NS has possible histone-like function. May be a global transcriptional regulator through its ability to bind to curved DNA sequences, which are found in regions upstream of a certain subset of promoters. It plays a role in the thermal control of pili production. It is subject to transcriptional auto-repression. It binds preferentially to the upstream region of its own gene recognizing two segments of DNA on both sides of a bend centered around -150 (By similarity).
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The bacterial nucleoid associated proteins Hha and H-NS jointly repress horizontally acquired genes in Salmonella, including essential virulence loci encoded within Salmonella pathogenicity islands. Hha is known to interact with the N-terminal dimerization domain of H-NS, however the manner in which this interaction enhances transcriptional silencing is not understood. To further understand this process we solved the X-ray crystal structure of Hha in complex with the N-terminal dimerization domain of H-NS (H-NS1-46) to 3.2 A resolution. Two monomers of Hha bind to symmetrical sites on either side of the H-NS1-46 dimer. Disruption of the Hha/H-NS interaction by the H-NS site-specific mutation I11A, results in increased expression of the Hha/H-NS co-regulated gene hilA without affecting the expression levels of proV, a target gene repressed by H-NS in an Hha-independent fashion. Examination of the structure revealed a cluster of conserved basic amino acids that protrude from the surface of Hha on the opposite side of the Hha/H-NS1-46 interface. Hha mutants with a diminished positively charged surface maintain the ability to interact with H-NS but can no longer regulate hilA. Increased expression of the hilA locus did not correspond to significant depletion of H-NS at the promoter region in chromatin immunoprecipitation assays. However in vitro, we find Hha improves H-NS binding to target DNA fragments. Taken together, our results show for the first time how Hha and H-NS interact to direct transcriptional repression and reveal that a positively charged surface of Hha enhances the silencing activity of H-NS nucleoprotein filaments.

Structural Insights into the Regulation of Foreign Genes in Salmonella by the Hha/H-NS Complex.,Ali SS, Whitney JC, Stevenson J, Robinson H, Howell PL, Navarre WW J Biol Chem. 2013 Mar 20. PMID:23515315<ref>PMID:23515315</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 4icg" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Salmonella enterica subsp. enterica serovar Typhimurium str. LT2]]
[[Category: Ali SS]]
[[Category: Howell PL]]
[[Category: Navarre WW]]
[[Category: Robinson H]]
[[Category: Stevenson J]]
[[Category: Whitney JC]]