Torrelo Guzman, Ribeiro de Souza Fayene Zeferino, Carrilho Emanuel, Hanefeld Ulf
Gebouw voor Scheikunde, Biokatalyse Afdeling Biotechnologie, Technische Universiteit Delft, Julianalaan 136, 2628 BL Delft (The Netherlands).
Chembiochem. 2015 Mar 2;16(4):625-30. doi: 10.1002/cbic.201402685. Epub 2015 Feb 12.
In 2009, we reported that the product of the gene SCJ21.16 (XFa0032) from Xylella fastidiosa, a xylem-restricted plant pathogen that causes a range of diseases in several important crops, encodes a protein (XfHNL) with putative hydroxynitrile lyase activity. Sequence analysis and activity tests indicated that XfHNL exhibits an α/β-hydrolase fold and could be classified as a member of the family of FAD-independent HNLs. Here we provide a more detailed sequence analysis and new experimental data. Using pure heterologously expressed XfHNL we show that this enzyme cannot catalyse the cleavage/synthesis of mandelonitrile and that this protein is in fact a non-enantioselective esterase. Homology modelling and ligand docking simulations were used to study the active site and support these results. This finding could help elucidate the common ancestor of esterases and hydroxynitrile lyases with an α/β -hydrolase fold.
2009年，我们报道了来自木质部限制型植物病原菌——苛养木杆菌（Xylella fastidiosa）的基因SCJ21.16（XFa0032）的产物，该病原菌会在几种重要作物中引发一系列疾病，其编码一种具有假定羟基腈裂解酶活性的蛋白质（XfHNL）。序列分析和活性测试表明，XfHNL呈现α/β-水解酶折叠结构，可归类为非依赖黄素腺嘌呤二核苷酸（FAD）的羟基腈裂解酶家族成员。在此，我们提供更详细的序列分析和新的实验数据。使用纯的异源表达XfHNL，我们发现这种酶不能催化扁桃腈的裂解/合成，并且该蛋白质实际上是一种非对映选择性酯酶。同源建模和配体对接模拟被用于研究活性位点并支持这些结果。这一发现有助于阐明具有α/β-水解酶折叠结构的酯酶和羟基腈裂解酶的共同祖先。
