title: Structure of a two-domain chitotriosidase from Serratia marcescens at 1.9-A resolution.
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.
authors.affiliation: Biocenter Oulu, Department of Biochemistry, University of Oulu, Linnanmaa, FIN-90570 Oulu, Finland. dava@davapc1.bioch.dundee.ac.uk
authors.forename: D M
authors.initials: DM
authors.lastname: van Aalten
authors.forename: B
authors.initials: B
authors.lastname: Synstad
authors.forename: M B
authors.initials: MB
authors.lastname: Brurberg
authors.forename: E
authors.initials: E
authors.lastname: Hough
authors.forename: B W
authors.initials: BW
authors.lastname: Riise
authors.forename: V G
authors.initials: VG
authors.lastname: Eijsink
authors.forename: R K
authors.initials: RK
authors.lastname: Wierenga
mesh_terms: D000117:Acetylglucosamine / Q000378:metabolism; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry*; D001665:Binding Sites; D020134:Catalytic Domain; D002686:Chitin / Q000378:metabolism; D002688:Chitinases / Q000737:chemistry; D018360:Crystallography, X-Ray; D006596:Hexosaminidases / Q000737:chemistry*; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009113:Muramidase / Q000737:chemistry; D010940:Plant Proteins / Q000737:chemistry; D011487:Protein Conformation; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D012706:Serratia marcescens / Q000201:enzymology*; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D010940:Plant Proteins; D002686:Chitin; D006596:Hexosaminidases; C086400:chitotriosidase; D002688:Chitinases; C094255:PLC-B protein, Phytolacca americana; C063764:hevamine; D009113:Muramidase; D000117:Acetylglucosamine