22hi | pdb_000022hi
Beta-1,2-glucan-binding protein complexed with cyclic beta-1,2-glucoheptadecaose
Structural highlights
FunctionPublication Abstract from PubMedbeta-1,2-Glucans are glucose polymers widely distributed in nature and play various physiological roles in the interactions between organisms such as pathogenicity and symbiosis. While various beta-1,2-glucan-degrading enzymes have been identified recently, transporters incorporating beta-1,2-glucans are still poorly characterized. In this study, we have found a beta-1,2-glucan binding protein of ABC transporter from Chloroflexus aurantiacus Y-400-fl, a filamentous anoxygenic phototrophic bacterium. The protein showed a clear affinity for linear beta-1,2-glucan in the gel shift assay. Isothermal titration calorimetric analysis revealed high binding affinities for both linear and cyclic beta-1,2-glucans, unlike for the barley beta-glucan. The recorded binding constants were high for the binding of the ABC transporter to beta-1,2-glucans. The observed unfavorable negative entropy change may have resulted from conformational restraints upon complex formation. Complex structures with linear beta-1,2-glucan and cyclic beta-1,2-glucans with degrees of polymerization of 17-20 were obtained using X-ray crystallography. Ten glucose units, designated A-J from the nonreducing end, were shared among the substrates in the complexes. Unit G is recognized by W74, W308, and D336, which are highly conserved residues within the phylogenetic group Chy400_4166. The substrate-binding mode of Chy400_4166 is completely different from that of the beta-1,2-glucooligosaccharide-binding protein from Listeria innocua. The discovery of a new type of beta-1,2-glucan-related binding protein has expanded our understanding of the metabolism of beta-1,2-glucans. Structural and thermodynamic analyses of a novel beta-1,2-glucan binding mode in the ABC transporter solute-binding protein Chy400_4166 from Chloroflexus aurantiacus.,Kato K, Kaneko T, Hirayama R, Tanaka N, Nakai H, Torigoe H, Nakajima M FEBS J. 2026 May 10. doi: 10.1111/febs.70576. PMID:42108234[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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