HUSCAP logo Hokkaido Univ. logo

Hokkaido University Collection of Scholarly and Academic Papers >
Graduate School of Agriculture / Faculty of Agriculture >
Peer-reviewed Journal Articles, etc >

Structural Elucidation of Dextran Degradation Mechanism by Streptococcus mutans Dextranase Belonging to Glycoside Hydrolase Family 66

Files in This Item:
JBC287-24_19916-19926.pdf6.75 MBPDFView/Open
Please use this identifier to cite or link to this item:http://hdl.handle.net/2115/51763

Title: Structural Elucidation of Dextran Degradation Mechanism by Streptococcus mutans Dextranase Belonging to Glycoside Hydrolase Family 66
Authors: Suzuki, Nobuhiro Browse this author
Kim, Young-Min Browse this author
Fujimoto, Zui Browse this author
Momma, Mitsuru Browse this author
Okuyama, Masayuki Browse this author →KAKEN DB
Mori, Haruhide Browse this author →KAKEN DB
Funane, Kazumi Browse this author
Kimura, Atsuo Browse this author →KAKEN DB
Keywords: dextranase
crystal structure
catalytic mechanism
Issue Date: 8-Jun-2012
Publisher: American Society for Biochemistry and Molecular Biology
Journal Title: Journal of Biological Chemistry
Volume: 287
Issue: 24
Start Page: 19916
End Page: 19926
Publisher DOI: 10.1074/jbc.M112.342444
Abstract: Dextranase is an enzyme that hydrolyzes dextran α-1,6 linkages. Streptococcus mutans dextranase (SmDex) belongs to glycoside hydrolase family 66, producing isomaltooligosaccharides of various sizes, and consisting of at least five amino acid sequence regions. The crystal structure of the conserved fragment from Gln-100 to Ile-732 of SmDex, devoid of its N and C-terminal variable regions, was determined at 1.6 Å resolution and found to contain three structural domains. Domain N possessed an immunoglobulin-like β-sandwich fold, domain A the enzyme's catalytic module, comprising a (β/α)8-barrel, and domain C formed a β-sandwich structure containing two Greek key motifs. Two ligand complex structures were also determined and, in the enzyme/isomaltotriose complex structure, the bound isomaltooligosaccharide with four glucose moieties was observed in the catalytic glycone cleft and considered to be the transglycosylation product of the enzyme, indicating the presence of four subsites -4 to -1 in the catalytic cleft. The complexed structure with 4',5'-epoxypentyl-α-D-glucopyranoside, a suicide substrate of the enzyme, revealed that the epoxide ring reacted to form a covalent bond with the Asp-385 sidechain. These structures collectively indicated that Asp-385 was the catalytic nucleophile and Glu-453 the acid/base of the double displacement mechanism, in which the enzyme showed a retaining catalytic character. This is the first structural report for a GH-66 enzyme elucidating the enzyme's catalytic machinery.
Rights: This research was originally published in Journal of Biological Chemistry. Nobuhiro Suzuki; Young-Min Kim; Zui Fujimoto; Mitsuru Momma; Masayuki Okuyama; Haruhide Mori; Kazumi Funane; Atsuo Kimura. Structural Elucidation of Dextran Degradation Mechanism by Streptococcus mutans Dextranase Belonging to Glycoside Hydrolase Family 66. Journal of Biological Chemistry. 2012; 287:19916-19926. © the American Society for Biochemistry and Molecular Biology.
Type: article (author version)
URI: http://hdl.handle.net/2115/51763
Appears in Collections:農学院・農学研究院 (Graduate School of Agriculture / Faculty of Agriculture) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 木村 淳夫

Export metadata:

OAI-PMH ( junii2 , jpcoar )


 

Feedback - Hokkaido University