Structural highlights
Publication Abstract from PubMedComplete degradation of the xylan backbone of hemicellulosic plant cell walls requires the synergistic action of endo-xylanases and beta-1,4-xylosidases. While endo-xylanases produce xylooligosaccharides from xylan, beta-1,4-xylosidases degrade the xylooligosaccharides into xylose monomers. The glycoside hydrolase family 43 beta-1,4-xylosidase from Geobacillus thermoleovorans IT-08 is a promising, heat stable catalyst for the saccharification of hemicellulosic material into simple fermentable sugars, but it is competitively inhibited by its products arabinose and xylose. As a first step to help overcome this problem, we elucidated crystal structures of the enzyme in the unliganded form and with bound products, at 1.7-2.0 A resolution. The structures are very similar to those of other enzymes belonging to glycoside hydrolase family 43. Unexpectedly, the monosaccharides are bound in very different ways. Arabinose preferentially binds in subsite -1, while xylose exclusively interacts with subsite +1. These structures and sugar binding preferences suggest ways for improving the catalytic performance of the enzyme by rational mutational design. Structural basis of product inhibition by arabinose and xylose of the thermostable GH43 beta-1,4-xylosidase from Geobacillus thermoleovorans IT-08.,Rohman A, van Oosterwijk N, Puspaningsih NNT, Dijkstra BW PLoS One. 2018 Apr 26;13(4):e0196358. doi: 10.1371/journal.pone.0196358., eCollection 2018. PMID:29698436[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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