6an5

<StructureSection load='6an5' size='340' side='right' caption='[[6an5]], [[Resolution|resolution]] 3.51&Aring;' scene=''>

<table><tr><td colspan='2'>[[6an5]] is a 2 chain structure with sequence from [http://en.wikipedia.org/wiki/Aquae Aquae]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6AN5 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6AN5 FirstGlance]. <br>

</td></tr><tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">abcT4, aq_1094 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=224324 AQUAE])</td></tr>

<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6an5 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6an5 OCA], [http://pdbe.org/6an5 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6an5 RCSB], [http://www.ebi.ac.uk/pdbsum/6an5 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6an5 ProSAT]</span></td></tr>

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== Publication Abstract from PubMed ==

O-antigens are cell surface polysaccharides of many Gram-negative pathogens that aid in escaping innate immune responses. A widespread O-antigen biosynthesis mechanism involves the synthesis of the lipid-anchored polymer on the cytosolic face of the inner membrane, followed by transport to the periplasmic side where it is ligated to the lipid A core to complete a lipopolysaccharide molecule. In this pathway, transport to the periplasm is mediated by an ATP-binding cassette (ABC) transporter, called Wzm-Wzt. Here we present the crystal structure of the Wzm-Wzt homologue from Aquifex aeolicus in an open conformation. The transporter forms a transmembrane channel that is sufficiently wide to accommodate a linear polysaccharide. Its nucleotide-binding domain and a periplasmic extension form 'gate helices' at the cytosolic and periplasmic membrane interfaces that probably serve as substrate entry and exit points. Site-directed mutagenesis of the gates impairs in vivo O-antigen secretion in the Escherichia coli prototype. Combined with a closed structure of the isolated nucleotide-binding domains, our structural and functional analyses suggest a processive O-antigen translocation mechanism, which stands in contrast to the classical alternating access mechanism of ABC transporters.

 

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== References ==

[[Category: Aquae]]

[[Category: Bi, Y]]

[[Category: Zimmer, J]]

[[Category: Nucleotide binding domain of abct4]]

[[Category: Transport protein]]