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Title | Molecular basis for polysaccharide recognition and modulated ATP hydrolysis by the O antigen ABC transporter. |
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Journal, issue, pages | Nat Commun, Vol. 13, Issue 1, Page 5226, Year 2022 |
Publish date | Sep 5, 2022 |
Authors | Nicholas Spellmon / Artur Muszyński / Ireneusz Górniak / Jiri Vlach / David Hahn / Parastoo Azadi / Jochen Zimmer / |
PubMed Abstract | O antigens are ubiquitous protective extensions of lipopolysaccharides in the extracellular leaflet of the Gram-negative outer membrane. Following biosynthesis in the cytosol, the lipid-linked ...O antigens are ubiquitous protective extensions of lipopolysaccharides in the extracellular leaflet of the Gram-negative outer membrane. Following biosynthesis in the cytosol, the lipid-linked polysaccharide is transported to the periplasm by the WzmWzt ABC transporter. Often, O antigen secretion requires the chemical modification of its elongating terminus, which the transporter recognizes via a carbohydrate-binding domain (CBD). Here, using components from A. aeolicus, we identify the O antigen structure with methylated mannose or rhamnose as its cap. Crystal and cryo electron microscopy structures reveal how WzmWzt recognizes this cap between its carbohydrate and nucleotide-binding domains in a nucleotide-free state. ATP binding induces drastic conformational changes of its CBD, terminating interactions with the O antigen. ATPase assays and site directed mutagenesis reveal reduced hydrolytic activity upon O antigen binding, likely to facilitate polymer loading into the ABC transporter. Our results elucidate critical steps in the recognition and translocation of polysaccharides by ABC transporters. |
External links | Nat Commun / PubMed:36064941 / PubMed Central |
Methods | EM (single particle) / X-ray diffraction |
Resolution | 1.61 - 4.1 Å |
Structure data | EMDB-27491, PDB-8dku: EMDB-27494, PDB-8dl0: EMDB-27556, PDB-8dn8: EMDB-27563, PDB-8dnc: EMDB-27564, PDB-8dne: EMDB-27623, PDB-8dou: PDB-8dky: |
Chemicals | ChemComp-U90: ChemComp-HOH: ChemComp-MG: ChemComp-ADP: ChemComp-ATP: |
Source |
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Keywords | TRANSLOCASE / O antigen / ABC transporter / CBD-dependent / SUGAR BINDING PROTEIN / O antigen ABC transporter / carbohydrate binding domain / 3-O-methyl-D-mannose |