Document Detail


Influencing the binding configuration of sucrose in the active sites of chicory fructan 1-exohydrolase and sugar beet fructan 6-exohydrolase.
MedLine Citation:
PMID:  18331426     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The hydrolytic plant enzymes of family 32 of glycoside hydrolases (GH32), including acid cell wall type invertases (EC 3.2.1.26), fructan 1-exohydrolases (1-FEH; EC 3.2.1.153) and fructan 6-exohydrolases (6-FEH; EC 3.2.1.154), are very similar at the molecular and structural levels, but are clearly functionally different. The work presented here aims at understanding the evolution of enzyme specificity and functional diversity in this family by means of site-directed mutagenesis. It is demonstrated for the first time that invertase activity can be introduced in an S101L mutant of chicory (Cichorium intybus) 1-FEH IIa by influencing the orientation of Trp 82. At high sucrose and enzyme concentrations, a shift is proposed from a stable inhibitor configuration to an unstable substrate configuration. In the same way, invertase activity was introduced in Beta vulgaris 6-FEH by introducing an acidic amino acid in the vicinity of the acid-base catalyst (F233D mutant), creating a beta-fructofuranosidase type of enzyme with dual activity against sucrose and levan. As single amino acid substitutions can influence the donor substrate specificity of FEHs, it is predicted that plant invertases and FEHs may have diversified by introduction of a very limited number of mutations in the common ancestor.
Authors:
Katrien Le Roy; Willem Lammens; André Van Laere; Wim Van den Ende
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't     Date:  2008-03-03
Journal Detail:
Title:  The New phytologist     Volume:  178     ISSN:  1469-8137     ISO Abbreviation:  New Phytol.     Publication Date:  2008  
Date Detail:
Created Date:  2008-04-22     Completed Date:  2008-10-27     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  9882884     Medline TA:  New Phytol     Country:  England    
Other Details:
Languages:  eng     Pagination:  572-80     Citation Subset:  IM    
Affiliation:
K. U. Leuven, Laboratory of Molecular Plant Physiology, Kasteelpark Arenberg 31, box 2434, B-3001 Leuven, Belgium.
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MeSH Terms
Descriptor/Qualifier:
Amino Acid Sequence
Beta vulgaris / enzymology*
Binding Sites
Chicory / enzymology*
Genetic Engineering
Glycoside Hydrolases / chemistry,  genetics*,  metabolism
Models, Molecular
Plant Proteins / chemistry,  genetics,  metabolism
Protein Binding
Protein Conformation
Substrate Specificity
Sucrose / chemistry*,  metabolism*
Chemical
Reg. No./Substance:
0/Plant Proteins; 57-50-1/Sucrose; EC 3.2.1.-/Glycoside Hydrolases

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine


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