View source for 6ivu


==Solution structure of the Sigma-anti-sigma factor complex RsgI1N-SigI1C from Clostridium thermocellum==
<StructureSection load='6ivu' size='340' side='right'caption='[[6ivu]]' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6ivu]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Acetivibrio_thermocellus_ATCC_27405 Acetivibrio thermocellus ATCC 27405]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6IVU OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=6IVU FirstGlance]. <br>
</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=6ivu FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6ivu OCA], [https://pdbe.org/6ivu PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=6ivu RCSB], [https://www.ebi.ac.uk/pdbsum/6ivu PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=6ivu ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/RSGI1_ACET2 RSGI1_ACET2] Anti-sigma factor for SigI1. Negatively regulates SigI1 activity through direct interaction (PubMed:20937888). Binding of the polysaccharide substrate to the extracellular C-terminal sensing domain of RsgI1 may induce a conformational change in its N-terminal cytoplasmic region, leading to the release and activation of SigI1 (Probable).<ref>PMID:20937888</ref> <ref>PMID:20937888</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
The sigma70 family alternative sigmaI factors and their cognate anti-sigmaI factors are widespread in Clostridia and Bacilli and play a role in heat stress response, virulence, and polysaccharide sensing. Multiple sigmaI/anti-sigmaI factors exist in some lignocellulolytic clostridial species, specifically for regulation of components of a multienzyme complex, termed the cellulosome. The sigmaI and anti-sigmaI factors are unique, because the C-terminal domain of sigmaI (SigIC) and the N-terminal inhibitory domain of anti-sigmaI (RsgIN) lack homology to known proteins. Here, we report structure and interaction studies of a pair of sigmaI and anti-sigmaI factors, SigI1 and RsgI1, from the cellulosome-producing bacterium, Clostridium thermocellum. In contrast to other known anti-sigma factors that have N-terminal helical structures, RsgIN has a beta-barrel structure. Unlike other anti-sigma factors that bind both sigma2 and sigma4 domains of the sigma factors, RsgIN binds SigIC specifically. Structural analysis showed that SigIC contains a positively charged surface region that recognizes the promoter -35 region, and the synergistic interactions among multiple interfacial residues result in the specificity displayed by different sigmaI/anti-sigmaI pairs. We suggest that the sigmaI/anti-sigmaI factors represent a distinctive mode of sigma/anti-sigma complex formation, which provides the structural basis for understanding the molecular mechanism of the intricate sigmaI/anti-sigmaI system.

Alternative sigmaI/anti-sigmaI factors represent a unique form of bacterial sigma/anti-sigma complex.,Wei Z, Chen C, Liu YJ, Dong S, Li J, Qi K, Liu S, Ding X, Ortiz de Ora L, Munoz-Gutierrez I, Li Y, Yao H, Lamed R, Bayer EA, Cui Q, Feng Y Nucleic Acids Res. 2019 May 20. pii: 5490815. doi: 10.1093/nar/gkz355. PMID:31106374<ref>PMID:31106374</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 6ivu" style="background-color:#fffaf0;"></div>

==See Also==
*[[Sigma factor 3D structures|Sigma factor 3D structures]]
== References ==
<references/>
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</StructureSection>
[[Category: Acetivibrio thermocellus ATCC 27405]]
[[Category: Large Structures]]
[[Category: Feng Y]]
[[Category: Wei Z]]