4xig

</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=BEM:BETA-D-MANNURONIC+ACID'>BEM</scene>, <scene name='pdbligand=MAW:4-DEOXY-ALPHA-L-ERYTHRO-HEX-4-ENOPYRANURONIC+ACID'>MAW</scene></td></tr>

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== Publication Abstract from PubMed ==

The Gram-negative bacterium Sphingomonas sp. A1 incorporates alginate into cells via the cell-surface pit without prior depolymerization by extracellular enzymes. Alginate import across cytoplasmic membranes thereby depends on the ATP-binding cassette transporter AlgM1M2SS (a heterotetramer of AlgM1, AlgM2, and AlgS), which cooperates with the periplasmic solute-binding protein AlgQ1 or AlgQ2; however, several details of AlgM1M2SS-mediated alginate import are not well-understood. Herein, we analyzed ATPase and transport activities of AlgM1M2SS after reconstitution into liposomes with AlgQ2 and alginate oligosaccharide substrates having different polymerization degrees (PDs). Longer alginate oligosaccharides (PD &gt;/= 5) stimulated the ATPase activity of AlgM1M2SS but were inert as substrates of AlgM1M2SS-mediated transport, indicating that AlgM1M2SS-mediated ATP hydrolysis can be stimulated independently of substrate transport. Using X-ray crystallography in the presence of AlgQ2 and long alginate oligosaccharides (PD 6-8) and with the humid air and glue-coating method, we determined the crystal structure of AlgM1M2SS in complex with oligosaccharide-bound AlgQ2 at 3.6 A resolution. The structure of the ATP-binding cassette transporter in complex with non-transport ligand-bound periplasmic solute-binding protein revealed that AlgM1M2SS and AlgQ2 adopt inward-facing and closed conformations, respectively. These in vitro assays and structural analyses indicated that interactions between AlgM1M2SS in the inward-facing conformation and periplasmic ligand-bound AlgQ2 in the closed conformation induce ATP hydrolysis by the ATP-binding protein AlgS. We conclude that substrate-bound AlgQ2 in the closed conformation initially interacts with AlgM1M2SS, the AlgM1M2SS-AlgQ2 complex then forms, and this formation is followed by ATP hydrolysis.

A solute-binding protein in the closed conformation induces ATP hydrolysis in a bacterial ATP-binding cassette transporter involved in the import of alginate.,Kaneko A, Uenishi K, Maruyama Y, Mizuno N, Baba S, Kumasaka T, Mikami B, Murata K, Hashimoto W J Biol Chem. 2017 Sep 22;292(38):15681-15690. doi: 10.1074/jbc.M117.793992. Epub , 2017 Aug 2. PMID:28768763<ref>PMID:28768763</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

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== References ==

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