Mátrai Janka, Lammens Willem, Jonckheer Abel, Le Roy Katrien, Rabijns Anja, Van den Ende Wim, De Maeyer Marc
Laboratory of Biomolecular Modelling and BioMacS, Department of Chemistry, Katholieke Universiteit Leuven, Belgium.
Proteins. 2008 May 1;71(2):552-64. doi: 10.1002/prot.21700.
In the present study, we report on the X-ray crystallographic structure of a GH32 invertase mutant, (i.e., the Arabidopsis thaliana cell-wall invertase 1-E203Q, AtcwINV1-mutant) in complex with sucrose. This structure was solved to reveal the features of sugar binding in the catalytic pocket. However, as demonstrated by the X-ray structure the sugar binding and the catalytic pocket arrangement is significantly altered as compared with what was expected based on previous X-ray structures on GH-J clan enzymes. We performed a series of docking and molecular dynamics simulations on various derivatives of AtcwINV1 to reveal the reasons behind this modified sugar binding. Our results demonstrate that the E203Q mutation introduced into the catalytic pocket triggers conformational changes that alter the wild type substrate binding. In addition, this study also reveals the putative productive sucrose binding modus in the wild type enzyme.
在本研究中，我们报道了一种GH32转化酶突变体（即拟南芥细胞壁转化酶1-E203Q，AtcwINV1-突变体）与蔗糖复合物的X射线晶体结构。解析该结构以揭示催化口袋中糖结合的特征。然而，如X射线结构所示，与基于先前GH-J家族酶的X射线结构所预期的情况相比，糖结合和催化口袋排列发生了显著改变。我们对AtcwINV1的各种衍生物进行了一系列对接和分子动力学模拟，以揭示这种修饰的糖结合背后的原因。我们的结果表明，引入催化口袋的E203Q突变引发了构象变化，改变了野生型底物结合。此外，本研究还揭示了野生型酶中假定的有效蔗糖结合模式。
