Structure of the Humicola insolens cellobiohydrolase Cel6A D416A mutant in complex with a non-hydrolysable substrate analogue, methyl cellobiosyl-4-thio-β-cellobioside, at 1.9 Å

被引:29
作者
Varrot, A
Frandsen, TP
Driguez, H
Davies, GJ [1 ]
机构
[1] Univ York, Struct Biol Lab, Dept Chem, York Y010 5YW, N Yorkshire, England
[2] Novozymes AS, DK-2880 Bagsvaerd, Denmark
[3] CNRS, Ctr Rech Macromol Vegetales, F-38041 Grenoble 9, France
来源
ACTA CRYSTALLOGRAPHICA SECTION D-STRUCTURAL BIOLOGY | 2002年 / 58卷
关键词
D O I
10.1107/S0907444902017006
中图分类号
Q5 [生物化学];
学科分类号
071010 ; 081704 ;
摘要
The enzymatic degradation of cellulose continues to be one of the most important enzyme-catalysed reactions. Glycoside hydrolases from family GH-6 hydrolyse cellulose with inversion of the configuration of the anomeric carbon. Whilst the catalytic proton donor has been clearly identified (Asp226 in Humicola insolens Cel6A), the identification and even the existence of a potential Bronsted base remains unclear. Equally controversial is the role of surface-loop flexibility. Here, the structure of the D416A mutant of the H. insolens cellobiohydrolase Cel6A in complex with a nonhydrolysable thiooligosaccharide methyl cellobiosyl-4-thio-beta-cellobioside at 1.9 Angstrom resolution is presented. Substrate distortion in the -1 subsite, to a S-2(0) skew-boat conformation, is observed, similar to that seen in the analogous Trichoderma reesei Cel6A structure [Zou et al. (1999), Structure, 7, 1035-1045], but the active-centre N-terminal loop of the H. insolens enzyme is found in a more open conformation than described for previous structures.
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页码:2201 / 2204
页数:4
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