Exchanging a single amino acid residue generates or weakens a +2 cellooligosaccharide binding subsite in rice β-glucosidases
| Autor: | Sompong Sansenya, Janjira Maneesan, James R. Ketudat Cairns |
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| Rok vydání: | 2012 |
| Předmět: |
Models
Molecular Protein Conformation Stereochemistry Oligosaccharides Biochemistry Analytical Chemistry Structure-Activity Relationship Hydrolysis chemistry.chemical_compound Residue (chemistry) Glycoside hydrolase Enzyme Inhibitors Laminaribiose chemistry.chemical_classification Glycoside hydrolase family 1 Binding Sites biology beta-Glucosidase Organic Chemistry Oryza General Medicine Oligosaccharide Amino Acid Substitution chemistry Cellooligosaccharide binding Mutagenesis Site-Directed biology.protein Glucosidases Protein Binding |
| Zdroj: | Carbohydrate Research. 351:130-133 |
| ISSN: | 0008-6215 |
| DOI: | 10.1016/j.carres.2012.01.010 |
| Popis: | Os3BGlu6, Os3BGlu7, and Os4BGlu12 are rice glycoside hydrolase family 1 β-glucosidases, the structures of which have been solved by X-ray crystallography. In complex structures, Os3BGlu7 residue Asn245 hydrogen bonds to the second sugar in the +1 subsite for laminaribiose and the third sugar in the +2 subsite for cellotetraose and cellopentaose. The corresponding Os3BGlu6 residue, Met251, appears to block the binding of cellooligosaccharides at the +2 subsite, whereas His252 in this position in Os4BGlu12 could hydrogen bond to oligosaccharides. Mutation of Os3BGlu6 Met251 to Asn resulted in a 15-fold increased k cat /K m value for hydrolysis of laminaribiose compared to wild type Os3BGlu6 and 9 to 24-fold increases for cellooligosaccharides with degrees of polymerization (DP) of 2–5. On the other hand, mutation of Os3BGlu7 Asn245 to Met decreased the k cat /K m of hydrolysis by 6.5-fold for laminaribiose and 17 to 30-fold for cellooligosaccharides with DP >2, while mutation of Os4BGlu12 His252 to Met decreased the corresponding k cat /K m values 2 to 6-fold. |
| Databáze: | OpenAIRE |
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