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Publication Abstract from PubMed

Glucuronic and/or methylglucuronic acid (GlcAp/MeGlcAp) decorate the major forms of xylan in hardwood and coniferous softwoods, as well as many cereal grains. Accordingly, the complete utilization of glucuronoxylans or conversion to sugar precursors requires the action of main chain xylanases as well as alpha-glucuronidases that release the alpha- (1-->2)-linked (Me)GlcAp side groups. Herein, a family GH115 enzyme from the marine bacterium Saccharophagus degradans 2-40T, SdeAgu115A, demonstrated activity towards glucuronoxylan and oligomers thereof with preference towards MeGlcAp linked to internal xylopyranosyl residues. Unique biochemical characteristics of NaCl activation was observed. The crystal structure of SdeAgu115A revealed a five-domain architecture, with an additional insertion C+ domain that had significant impact to the domain arrangement of SdeAgu115A monomer and its dimerization. The participation of domain C+ in substrate binding was supported by reduced substrate inhibition upon introducing W773A, W689A and F696A substitutions within this domain. In addition to D335, the catalytic essentiality of E216 was revealed by site-specific mutagenesis. A primary sequence analysis suggested that the SdeAgu115A architecture is shared by more than half of GH115 members, thus defining a distinct archetype for GH115 enzymes.

Biochemical and Structural Characterization of a Five-domain GH115 alpha-Glucuronidase from the Marine Bacterium Saccharophagus degradans 2-40T.,Wang W, Yan R, Nocek BP, Voung TV, Leo RD, Xu X, Cui H, Gatenholm P, Toriz G, Tenkanen M, Savchenko A, Master ER J Biol Chem. 2016 Apr 18. pii: jbc.M115.702944. PMID:27129264^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.