Crystal structure of a lactosucrose-producing enzyme, Arthrobacter sp. K-1 β-fructofuranosidase.

Takashi Tonozuka, Akiko Tamaki, Gaku Yokoi, Takatsugu Miyazaki, Megumi Ichikawa, Atsushi Nishikawa, Yukari Ohta, Yuko Hidaka, Kinya Katayama, Yuji Hatada, Tetsuya Ito, Koki Fujita

Department of Applied Biological Science, Tokyo University of Agriculture and Technology, 3-5-8 Saiwai-cho, Fuchu, Tokyo 186-0001, Japan. tonozuka@cc.tuat.ac.jp

Enzyme and microbial technology 2012 Dec 10

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Arthrobacter sp. K-1 β-fructofuranosidase (ArFFase), a glycoside hydrolase family 68 enzyme, catalyzes the hydrolysis and transfructosylation of sucrose. ArFFase is useful for producing a sweetener, lactosucrose (4(G)-β-D-galactosylsucrose). The primary structure of ArFFase is homologous to those of levansucrases, although ArFFase catalyzes mostly hydrolysis when incubated with sucrose alone, even at high concentration. Here, we determined the crystal structure of ArFFase in unliganded form and complexed with fructose. ArFFase consisted of a five-bladed β-propeller fold as observed in levansucrases. The structure of ArFFase was most similar to that of Gluconacetobacter diazotrophicus levansucrase (GdLev). The structure of the catalytic cleft of ArFFase was also highly homologous to that of GdLev. However, two amino acid residues, Tyr232 and Pro442 in ArFFase, were not conserved between them. A tunnel observed at the bottom of the catalytic cleft of ArFFase may serve as a water drain or its reservoir. Copyright © 2012 Elsevier Inc. All rights reserved.

Citation

Takashi Tonozuka, Akiko Tamaki, Gaku Yokoi, Takatsugu Miyazaki, Megumi Ichikawa, Atsushi Nishikawa, Yukari Ohta, Yuko Hidaka, Kinya Katayama, Yuji Hatada, Tetsuya Ito, Koki Fujita. Crystal structure of a lactosucrose-producing enzyme, Arthrobacter sp. K-1 β-fructofuranosidase. Enzyme and microbial technology. 2012 Dec 10;51(6-7):359-65