2x8t
From Proteopedia
Crystal Structure of the Abn2 H318A mutant
Structural highlights
FunctionEABN2_BACSU Involved in the degradation of arabinan and is a key enzyme in the complete degradation of the plant cell wall. Catalyzes the internal cleavage of alpha-(1->5)-L-arabinofuranosyl residues of the alpha-1,5-L-arabinan to produce arabino-oligosaccharides and L-arabinose. It is also active toward linear branched sugar beet arabinan, and pectin from apple.[1] [2] Publication Abstract from PubMedEndo-1,5-alpha-l-arabinanases are glycosyl hydrolases that are able to cleave the glycosidic bonds of alpha-1,5-l-arabinan, releasing arabino-oligosaccharides and l-arabinose. Two extracellular endo-1,5-alpha-l-arabinanases have been isolated from Bacillus subtilis, BsArb43A and BsArb43B (formally named AbnA and Abn2, respectively). BsArb43B shows low sequence identity with previously characterized 1,5-alpha-l-arabinanases and is a much larger enzyme. Here we describe the 3D structure of native BsArb43B, biochemical and structure characterization of two BsArb43B mutant proteins (H318A and D171A), and the 3D structure of the BsArb43B D171A mutant enzyme in complex with arabinohexose. The 3D structure of BsArb43B is different from that of other structurally characterized endo-1,5-alpha-l-arabinanases, as it comprises two domains, an N-terminal catalytic domain, with a 3D fold similar to that observed for other endo-1,5-alpha-l-arabinanases, and an additional C-terminal domain. Moreover, this work also provides experimental evidence for the presence of a cluster containing a calcium ion in the catalytic domain, and the importance of this calcium ion in the enzymatic mechanism of BsArb43B. New evidence for the role of calcium in the glycosidase reaction of GH43 arabinanases.,De Sanctis D, Inacio JM, Lindley PF, De Sa-Nogueira I, Bento I FEBS J. 2010 Sep 10. doi: 10.1111/j.1742-4658.2010.07870.x. PMID:20883454[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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