View source for 5lj8


==Structure of the E. coli MacB periplasmic domain (P21)==
<StructureSection load='5lj8' size='340' side='right'caption='[[5lj8]], [[Resolution|resolution]] 1.95&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5lj8]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli_K-12 Escherichia coli K-12]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5LJ8 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5LJ8 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]] 1.95&#8491;</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=5lj8 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5lj8 OCA], [https://pdbe.org/5lj8 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5lj8 RCSB], [https://www.ebi.ac.uk/pdbsum/5lj8 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5lj8 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/MACB_ECOLI MACB_ECOLI] Part of the tripartite efflux system MacAB-TolC. MacB is a non-canonical ABC transporter that contains transmembrane domains (TMD), which form a pore in the inner membrane, and an ATP-binding domain (NBD), which is responsible for energy generation. When overexpressed, the system confers resistance against macrolides composed of 14- and 15-membered lactones but no or weak resistance against 16-membered ones. In addition, the system could also transport R-LPS or a similar glycolipid.<ref>PMID:11544226</ref> <ref>PMID:17214741</ref> <ref>PMID:18955484</ref> <ref>PMID:23974027</ref> 
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
MacB is an ABC transporter that collaborates with the MacA adaptor protein and TolC exit duct to drive efflux of antibiotics and enterotoxin STII out of the bacterial cell. Here we present the structure of ATP-bound MacB and reveal precise molecular details of its mechanism. The MacB transmembrane domain lacks a central cavity through which substrates could be passed, but instead conveys conformational changes from one side of the membrane to the other, a process we term mechanotransmission. Comparison of ATP-bound and nucleotide-free states reveals how reversible dimerization of the nucleotide binding domains drives opening and closing of the MacB periplasmic domains via concerted movements of the second transmembrane segment and major coupling helix. We propose that the assembled tripartite pump acts as a molecular bellows to propel substrates through the TolC exit duct, driven by MacB mechanotransmission. Homologs of MacB that do not form tripartite pumps, but share structural features underpinning mechanotransmission, include the LolCDE lipoprotein trafficking complex and FtsEX cell division signaling protein. The MacB architecture serves as the blueprint for understanding the structure and mechanism of an entire ABC transporter superfamily and the many diverse functions it supports.

Structure and mechanotransmission mechanism of the MacB ABC transporter superfamily.,Crow A, Greene NP, Kaplan E, Koronakis V Proc Natl Acad Sci U S A. 2017 Nov 6. pii: 201712153. doi:, 10.1073/pnas.1712153114. PMID:29109272<ref>PMID:29109272</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5lj8" style="background-color:#fffaf0;"></div>
== References ==
<references/>
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</StructureSection>
[[Category: Escherichia coli K-12]]
[[Category: Large Structures]]
[[Category: Crow A]]