Department of Biology, Faculty of Natural Sciences, University of Ss. Cyril and Methodius, SK-91701 Trnava, Slovakia.
Laboratory of Protein Evolution, Institute of Molecular Biology, Slovak Academy of Sciences, SK-84551 Bratislava, Slovakia.
Molecules. 2021 Sep 21;26(18):5704. doi: 10.3390/molecules26185704.
This study brings a detailed bioinformatics analysis of fungal and chloride-dependent α-amylases from the family GH13. Overall, 268 α-amylase sequences were retrieved from subfamilies GH13_1 (39 sequences), GH13_5 (35 sequences), GH13_15 (28 sequences), GH13_24 (23 sequences), GH13_32 (140 sequences) and GH13_42 (3 sequences). Eight conserved sequence regions (CSRs) characteristic for the family GH13 were identified in all sequences and respective sequence logos were analysed in an effort to identify unique sequence features of each subfamily. The main emphasis was given on the subfamily GH13_32 since it contains both fungal α-amylases and their bacterial chloride-activated counterparts. In addition to in silico analysis focused on eventual ability to bind the chloride anion, the property typical mainly for animal α-amylases from subfamilies GH13_15 and GH13_24, attention has been paid also to the potential presence of the so-called secondary surface-binding sites (SBSs) identified in complexed crystal structures of some particular α-amylases from the studied subfamilies. As template enzymes with already experimentally determined SBSs, the α-amylases from (GH13_1), , and (all from GH13_5) and (saliva; GH13_24) were used. Evolutionary relationships between GH13 fungal and chloride-dependent α-amylases were demonstrated by two evolutionary trees-one based on the alignment of the segment of sequences spanning almost the entire catalytic TIM-barrel domain and the other one based on the alignment of eight extracted CSRs. Although both trees demonstrated similar results in terms of a closer evolutionary relatedness of subfamilies GH13_1 with GH13_42 including in a wider sense also the subfamily GH13_5 as well as for subfamilies GH13_32, GH13_15 and GH13_24, some subtle differences in clustering of particular α-amylases may nevertheless be observed.
本研究对 GH13 家族的真菌和氯依赖性α-淀粉酶进行了详细的生物信息学分析。总体上,从 GH13_1(39 个序列)、GH13_5(35 个序列)、GH13_15(28 个序列)、GH13_24(23 个序列)、GH13_32(140 个序列)和 GH13_42(3 个序列)亚家族中检索到 268 个α-淀粉酶序列。在所有序列中鉴定出 8 个家族 GH13 特征性的保守序列区(CSR),并对相应的序列标志进行了分析,以确定每个亚家族的独特序列特征。重点放在 GH13_32 亚家族上,因为它既包含真菌α-淀粉酶,也包含其细菌氯激活对应物。除了针对可能结合氯离子的能力的计算机分析外,这种能力主要是亚家族 GH13_15 和 GH13_24 中的动物α-淀粉酶所具有的特性,还关注了在研究的亚家族中一些特定α-淀粉酶的复合物晶体结构中所鉴定的所谓二级表面结合位点(SBS)的存在可能性。作为具有已实验确定 SBS 的模板酶,使用了来自 GH13_1(1)、(2)、(3)和(4)(均来自 GH13_5)和(唾液;GH13_24)的α-淀粉酶。通过基于跨越几乎整个催化 TIM 桶结构域的序列片段的比对的两棵进化树和基于提取的 8 个 CSR 的比对的另一棵进化树,证明了 GH13 真菌和氯依赖性α-淀粉酶之间的进化关系。尽管两棵树在亚家族 GH13_1 与包括广义上的 GH13_5 以及亚家族 GH13_32、GH13_15 和 GH13_24 的 GH13_42 之间的进化关系更为密切方面表现出相似的结果,但在特定α-淀粉酶聚类方面可能观察到一些细微的差异。