View source for 9bhe


==Salmonella undecaprenyl-phosphate 4-deoxy-4-formamido-L-arabinose transferase (ArnC) bound to UDP==
<StructureSection load='9bhe' size='340' side='right'caption='[[9bhe]], [[Resolution|resolution]] 3.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[9bhe]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Salmonella Salmonella]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=9BHE OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=9BHE FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.8&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=UDP:URIDINE-5-DIPHOSPHATE'>UDP</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=9bhe FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=9bhe OCA], [https://pdbe.org/9bhe PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=9bhe RCSB], [https://www.ebi.ac.uk/pdbsum/9bhe PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=9bhe ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/A0A663DHR7_SALER A0A663DHR7_SALER] Catalyzes the transfer of 4-deoxy-4-formamido-L-arabinose from UDP to undecaprenyl phosphate. The modified arabinose is attached to lipid A and is required for resistance to polymyxin and cationic antimicrobial peptides.[HAMAP-Rule:MF_01164]
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== Publication Abstract from PubMed ==
Polymyxins are last-resort antimicrobial peptides administered clinically against multi-drug resistant bacteria, specifically in the case of Gram-negative species. However, an increasing number of these pathogens employ a defense strategy that involves a relay of enzymes encoded by the pmrE (ugd) loci and the arnBCDTEF operon. The pathway modifies the lipid-A component of the outer membrane (OM) lipopolysaccharide (LPS) by adding a 4-amino-4-deoxy-l-arabinose (L-Ara4N) headgroup, which renders polymyxins ineffective. Here, we report the cryo-EM SPR structures of glycosyltransferase ArnC from Salmonella typhimurium determined in apo and UDP-bound forms at resolutions 2.75 A and 3.8 A, respectively. The structure of the ArnC protomer comprises three distinct regions: an N-terminal glycosyltransferase domain, transmembrane region, and the interface helices (IHs). ArnC forms a tetramer with C2 symmetry, where the C-terminal strand inserts into the adjacent protomer. This tetrameric state is further stabilized by two distinct interfaces formed by ArnC that form a network of hydrogen bonds and salt bridges. The binding of UDP induces conformational changes that stabilize the loop between residues H201 to S213, and part of the putative catalytic pocket formed by IH1 and IH2. The surface property analysis revealed a hydrophobic cavity formed by TM1 and TM2 in the apo state, which is disrupted upon UDP binding. The comparison of ArnC structures to their homologs GtrB and DPMS suggests the key residues involved in ArnC catalytic activity.

Cryo-EM SPR structures of Salmonella typhimurium ArnC; the key enzyme in lipid-A modification conferring polymyxin resistance.,Patel DH, Karimullina E, Guo Y, Semper C, Patel DT, Emde T, Borek D, Savchenko A Protein Sci. 2025 Feb;34(2):e70037. doi: 10.1002/pro.70037. PMID:39865303<ref>PMID:39865303</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 9bhe" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Large Structures]]
[[Category: Salmonella]]
[[Category: Borek D]]
[[Category: Guo Y]]