View source for 8qa8


==Crystal structure of the C-terminally truncated transcriptional repressor protein KorB from the RK2 plasmid complexed with CTP-gamma-S==
<StructureSection load='8qa8' size='340' side='right'caption='[[8qa8]], [[Resolution|resolution]] 2.30&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[8qa8]] is a 6 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=8QA8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=8QA8 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]] 2.3&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=CL:CHLORIDE+ION'>CL</scene>, <scene name='pdbligand=CTP:CYTIDINE-5-TRIPHOSPHATE'>CTP</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=8qa8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=8qa8 OCA], [https://pdbe.org/8qa8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=8qa8 RCSB], [https://www.ebi.ac.uk/pdbsum/8qa8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=8qa8 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/KORB2_ECOLX KORB2_ECOLX] In conjunction with KorA, inhibits the transcription of the kilA, trfA and korAB operons. Is also involved in the negative control of the kilB operon.
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
Examples of long-range gene regulation in bacteria are rare and generally thought to involve DNA looping. Here, using a combination of biophysical approaches including X-ray crystallography and single-molecule analysis for the KorB-KorA system in Escherichia coli, we show that long-range gene silencing on the plasmid RK2, a source of multi-drug resistance across diverse Gram-negative bacteria, is achieved cooperatively by a DNA-sliding clamp, KorB, and a clamp-locking protein, KorA. We show that KorB is a CTPase clamp that can entrap and slide along DNA to reach distal target promoters up to 1.5 kb away. We resolved the tripartite crystal structure of a KorB-KorA-DNA co-complex, revealing that KorA latches KorB into a closed clamp state. DNA-bound KorA thus stimulates repression by stalling KorB sliding at target promoters to occlude RNA polymerase holoenzymes. Together, our findings explain the mechanistic basis for KorB role switching from a DNA-sliding clamp to a co-repressor and provide an alternative mechanism for long-range regulation of gene expression in bacteria.

KorB switching from DNA-sliding clamp to repressor mediates long-range gene silencing in a multi-drug resistance plasmid.,McLean TC, Balaguer-Perez F, Chandanani J, Thomas CM, Aicart-Ramos C, Burick S, Olinares PDB, Gobbato G, Mundy JEA, Chait BT, Lawson DM, Darst SA, Campbell EA, Moreno-Herrero F, Le TBK Nat Microbiol. 2025 Feb;10(2):448-467. doi: 10.1038/s41564-024-01915-3. Epub 2025 , Jan 23. PMID:39849085<ref>PMID:39849085</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 8qa8" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Lawson DM]]
[[Category: Le TBK]]
[[Category: McLean TC]]
[[Category: Mundy JEA]]