Structure of a two-domain chitotriosidase from Serratia marcescens at 1.9-A resolution.
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van Aalten DM, Synstad B, Brurberg MB, Hough E, Riise BW, Eijsink VG, Wierenga RK
Structure of a two-domain chitotriosidase from Serratia marcescens at 1.9-A resolution.
Proc Natl Acad Sci U S A. 2000 May 23;97(11):5842-7.
- PubMed ID
- 10823940 [ View in PubMed]
- Abstract
In this paper, we describe the structure of chitinase B from Serratia marcescens, which consists of a catalytic domain with a TIM-barrel fold and a 49-residue C-terminal chitin-binding domain. This chitinase is the first structure of a bacterial exochitinase, and it represents one of only a few examples of a glycosyl hydrolase structure having interacting catalytic and substrate-binding domains. The chitin-binding domain has exposed aromatic residues that contribute to a 55-A long continuous aromatic stretch extending into the active site. Binding of chitin oligomers is blocked beyond the -3 subsite, which explains why the enzyme has chitotriosidase activity and degrades the chitin chain from the nonreducing end. Comparison of the chitinase B structure with that of chitinase A explains why these enzymes act synergistically in the degradation of chitin.