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The three-dimensional structure of beta-fructosidase (invertase) from Thermotoga maritima
Structural highlights
FunctionBFRA_THEMA Hydrolysis of sucrose, raffinose, inulin and levan. Specific for the fructose moiety and the beta-anomeric configuration of the glycosidic linkages of its substrates. The enzyme released fructose from sucrose and raffinose, and the fructose polymer inulin is hydrolyzed quantitatively in an exo-type fashion. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedThermotoga maritima invertase (beta-fructosidase) hydrolyzes sucrose to release fructose and glucose, which are major carbon and energy sources for both prokaryotes and eukaryotes. The name "invertase" was given to this enzyme over a century ago, because the 1:1 mixture of glucose and fructose that it produces was named "invert sugar." Despite its name, the enzyme operates with a mechanism leading to the retention of the anomeric configuration at the site of cleavage. The enzyme belongs to family GH32 of the sequence-based classification of glycosidases. The crystal structure, determined at 2-A resolution, reveals two modules, namely a five-bladed beta-propeller with structural similarity to the beta-propeller structures of glycosidase from families GH43 and GH68 connected to a beta-sandwich module. Three carboxylates at the bottom of a deep, negatively charged funnel-shaped depression of the beta-propeller are essential for catalysis and function as nucleophile, general acid, and transition state stabilizer, respectively. The catalytic machinery of invertase is perfectly superimposable to that of the enzymes of families GH43 and GH68. The variation in the position of the furanose ring at the site of cleavage explains the different mechanisms evident in families GH32 and GH68 (retaining) and GH43 (inverting) furanosidases. The three-dimensional structure of invertase (beta-fructosidase) from Thermotoga maritima reveals a bimodular arrangement and an evolutionary relationship between retaining and inverting glycosidases.,Alberto F, Bignon C, Sulzenbacher G, Henrissat B, Czjzek M J Biol Chem. 2004 Apr 30;279(18):18903-10. Epub 2004 Feb 18. PMID:14973124[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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