PMID:18467126

Citation	Songsiriritthigul, C, Pantoom, S, Aguda, AH, Robinson, RC and Suginta, W (2008) Crystal structures of Vibrio harveyi chitinase A complexed with chitooligosaccharides: implications for the catalytic mechanism. J. Struct. Biol. 162:491-9
Abstract	This research describes four X-ray structures of Vibrio harveyi chitinase A and its catalytically inactive mutant (E315M) in the presence and absence of substrates. The overall structure of chitinase A is that of a typical family-18 glycosyl hydrolase comprising three distinct domains: (i) the amino-terminal chitin-binding domain; (ii) the main catalytic (alpha/beta)(8) TIM-barrel domain; and (iii) the small (alpha+beta) insertion domain. The catalytic cleft of chitinase A has a long, deep groove, which contains six chitooligosaccharide ring-binding subsites (-4)(-3)(-2)(-1)(+1)(+2). The binding cleft of the ligand-free E315M is partially blocked by the C-terminal (His)(6)-tag. Structures of E315M-chitooligosaccharide complexes display a linear conformation of pentaNAG, but a bent conformation of hexaNAG. Analysis of the final 2F(o)-F(c) omit map of E315M-NAG6 reveals the existence of the linear conformation of the hexaNAG at a lower occupancy with respect to the bent conformation. These crystallographic data provide evidence that the interacting sugars undergo conformational changes prior to hydrolysis by the wild-type enzyme.
Links	PubMed Online version:10.1016/j.jsb.2008.03.008
Keywords	Binding Sites; Catalysis; Catalytic Domain; Chitin/chemistry; Chitinase/chemistry; Cloning, Molecular; Crystallography, X-Ray/methods; Hydrolysis; Molecular Conformation; Mutation; Oligosaccharides/chemistry; Protein Binding; Protein Structure, Secondary; Protein Structure, Tertiary; Vibrio/enzymology
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Annotations

Gene product	Qualifier	GO Term	Evidence Code	with/from	Aspect	Extension	Notes	Status
VIBHA:Q9AMP1		GO:0006032: chitin catabolic process	ECO:0000315:		P		Figure two shows specific chitin related binding with hydrogen bonds as dashed lines. NAG6 binds in the mutant variants well but results in a conformational change	complete CACAO 10120

References

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