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Structural basis for cyclodextrin recognition by Thermoactinomyces vulgaris cyclo/maltodextrin-binding protein.

Authors :
Tonozuka, Takashi
Sogawa, Akiko
Yamada, Mitsugu
Matsumoto, Naoki
Yoshida, Hiromi
Kamitori, Shigehiro
Ichikawa, Kazuhiro
Mizuno, Masahiro
Nishikawa, Atsushi
Sakano, Yoshiyuki
Source :
FEBS Journal. Apr2007, Vol. 274 Issue 8, p2109-2120. 12p. 7 Diagrams, 2 Charts.
Publication Year :
2007

Abstract

The crystal structure of a Thermoactinomyces vulgaris cyclo/maltodextrin-binding protein ( TvuCMBP) complexed with γ-cyclodextrin has been determined. Like Escherichia coli maltodextrin-binding protein ( EcoMBP) and other bacterial sugar-binding proteins, TvuCMBP consists of two domains, an N- and a C-domain, both of which are composed of a central β-sheet surrounded by α-helices; the domains are joined by a hinge region containing three segments. γ-Cyclodextrin is located at a cleft formed by the two domains. A common functional conformational change has been reported in this protein family, which involves switching from an open form to a sugar-transporter bindable form, designated a closed form. The TvuCMBP–γ-cyclodextrin complex structurally resembles the closed form of EcoMBP, indicating that TvuCMBP complexed with γ-cyclodextrin adopts the closed form. The fluorescence measurements also showed that the affinities of TvuCMBP for cyclodextrins were almost equal to those for maltooligosaccharides. Despite having similar folds, the sugar-binding site of the N-domain part of TvuCMBP and other bacterial sugar-binding proteins are strikingly different. In TvuCMBP, the side-chain of Leu59 protrudes from the N-domain part into the sugar-binding cleft and orients toward the central cavity of γ-cyclodextrin, thus Leu59 appears to play the key role in binding. The cleft of the sugar-binding site of TvuCMBP is also wider than that of EcoMBP. These findings suggest that the sugar-binding site of the N-domain part and the wide cleft are critical in determining the specificity of TvuCMBP for γ-cyclodextrin. [ABSTRACT FROM AUTHOR]

Details

Language :
English
ISSN :
1742464X
Volume :
274
Issue :
8
Database :
Academic Search Index
Journal :
FEBS Journal
Publication Type :
Academic Journal
Accession number :
24594374
Full Text :
https://doi.org/10.1111/j.1742-4658.2007.05753.x