10 September 2017: Sussing-out starch recognition in CBM58:
We are excited to report that Nicole Koropatkin
has completed the Carbohydrate Binding Module Family 58
page today. CBM58
constitutes a comparatively small family of CBMs found in bacteria in the phylum Bacteroidetes, including key members of the human gut microbiota such as Bacteroides thetaiotaomicron
. Within these bacteria, CBM58
modules are found inserted within the GH13
catalytic module of SusG, the essential outer-membrane-bound amylase of the starch utilization system (sus). Nicole’s
seminal structural biology has defined the family and provided insight into the recognition of amylose helices by CBM58
members in SusG homologs. Read more about this fascinating system here.
10 April 2017: A classic GH family: The Glycoside Hydrolase Family 22 page was completed today by Spencer Williams, with editorial input from Responsible Curator David Vocadlo. GH22 contains the classic bacterial peptidoglycan hydrolase, hen egg-white lysozyme (HEWL), the first enzyme for which the three-dimensional structure was solved (reported in 1965). Moreover, seminal enzyme-carbohydrate complex structures have made HEWL a paradigm for glycosidases that operate through the classical Koshland retaining mechanism. Although the nature of the reaction intermediate remained contentious for many years since the original proposal of an oxacarbenium ion-carboxylate pair, a definitive study by Vocadlo, Davies, Laine, and Withers resolved the covalent nature of the glycosyl-enzyme HEWL in 2001, thus bringing mechanistic understanding of this classic enzyme in concordance with other retaining GH families. The lysozyme fold of HEWL defines the archetype for other hexosaminidases (i.e. those of GH19 and GH23) and the non-catalytic alpha-lactalbumins, and this fold notably has also been observed in recently emergent families of cellulases (GH124) and mannanases (GH134). Find out more about this classic GH family here!
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