Dataset Information

Molecular basis for the recognition of long-chain substrates by plant ?-glucosidases.

ABSTRACT: Sugar beet ?-glucosidase (SBG), a member of glycoside hydrolase family 31, shows exceptional long-chain specificity, exhibiting higher kcat/Km values for longer malto-oligosaccharides. However, its amino acid sequence is similar to those of other short chain-specific ?-glucosidases. To gain structural insights into the long-chain substrate recognition of SBG, a crystal structure complex with the pseudotetrasaccharide acarbose was determined at 1.7 ? resolution. The active site pocket of SBG is formed by a (?/?)8 barrel domain and a long loop (N-loop) bulging from the N-terminal domain similar to other related enzymes. Two residues (Phe-236 and Asn-237) in the N-loop are important for the long-chain specificity. Kinetic analysis of an Asn-237 mutant enzyme and a previous study of a Phe-236 mutant enzyme demonstrated that these residues create subsites +2 and +3. The structure also indicates that Phe-236 and Asn-237 guide the reducing end of long substrates to subdomain b2, which is an additional element inserted into the (?/?)8 barrel domain. Subdomain b2 of SBG includes Ser-497, which was identified as the residue at subsite +4 by site-directed mutagenesis.

SUBMITTER: Tagami T

PROVIDER: S-EPMC3696700 | biostudies-literature | 2013 Jun

REPOSITORIES: biostudies-literature

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Publications

Molecular basis for the recognition of long-chain substrates by plant α-glucosidases.

Tagami Takayoshi T Yamashita Keitaro K Okuyama Masayuki M Mori Haruhide H Yao Min M Kimura Atsuo A

The Journal of biological chemistry 20130516 26

Sugar beet α-glucosidase (SBG), a member of glycoside hydrolase family 31, shows exceptional long-chain specificity, exhibiting higher kcat/Km values for longer malto-oligosaccharides. However, its amino acid sequence is similar to those of other short chain-specific α-glucosidases. To gain structural insights into the long-chain substrate recognition of SBG, a crystal structure complex with the pseudotetrasaccharide acarbose was determined at 1.7 Å resolution. The active site pocket of SBG is f ...[more]

PMID: 23687304

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Dataset Information

Molecular basis for the recognition of long-chain substrates by plant ?-glucosidases.

Publications

Molecular basis for the recognition of long-chain substrates by plant α-glucosidases.

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