5gkq

Structure of PL6 family alginate lyase AlyGC mutant-R241A

spinqualitylabelsall models 5gkq, resolution 2.56Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 5gkq is a 2 chain structure with sequence from Paraglaciecola chathamensis S18K6. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.565Å Ligands: BEM, CA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A0A1S4NYD8_9ALTE Publication Abstract from PubMed Alginate lyases that degrade alginate via a beta-elimination reaction fall into seven polysaccharide lyase (PL) families. Although the structures and catalytic mechanisms of alginate lyases in the other PL families have been clarified, those in family PL6 have yet to be revealed. Here, the crystal structure of AlyGC, a PL6 alginate lyase from marine bacterium Glaciecola chathamensis S18K6T, was solved, and its catalytic mechanism was illustrated. AlyGC is a homodimeric enzyme and adopts a structure distinct from other alginate lyases. Each monomer contains a catalytic N-terminal domain and a functionally unknown C-terminal domain. A combined structural and mutational analysis using the structures of AlyGC and of an inactive mutant R241A in complex with an alginate tetrasaccharide indicates that conformational changes occur in AlyGC when a substrate is bound and that the two active centers in AlyGC may not bind substrates simultaneously. The C-terminal domain is shown to be essential for the dimerization and the catalytic activity of AlyGC. Residues Tyr130, Arg187, His242, Arg265, and Tyr304 in the active center are also important for the activity of AlyGC. In catalysis, Lys220 and Arg241 function as the Bronsted base and acid, respectively, and a Ca2+ in the active center neutralizes the negative charge of the C5 carboxyl group of the substrate. Finally, based on our data, we propose a metal ion-assisted catalytic mechanism of AlyGC for alginate cleavage with a state change mode, which provides a better understanding for polysaccharide lyases and alginate degradation. Novel Molecular Insights into the Catalytic Mechanism of Marine Bacterial Alginate Lyase AlyGC from Polysaccharide Lyase Family 6.,Xu F, Dong F, Wang P, Cao HY, Li CY, Li PY, Pang XH, Zhang YZ, Chen XL J Biol Chem. 2017 Mar 17;292(11):4457-4468. doi: 10.1074/jbc.M116.766030. Epub, 2017 Feb 1. PMID:28154171 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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