Structure and Evolution of Glycogen Branching Enzyme N-Termini From Bacteria

作者：Liang Wang, Qinghua Liu, Junfeng Hu, James Asenso, Michael J. Wise, Xiang Wu, Chao Ma, Xiuqing Chen, Jianye Yang, Daoquan Tang · 发表于：Frontiers in Microbiology · 年份：2019 · DOI：10.3389/fmicb.2018.03354 · 被引用次数：37 · 研究领域：Genomics and Phylogenetic Studies、Glycosylation and Glycoproteins Research、Enzyme Production and Characterization

In bacteria, glycogen plays important roles in carbon and energy storage. Its structure has been linked with bacterial environmental durability. Among the essential genes for bacterial glycogen metabolism, glgB-encoded branching enzyme GBE plays an essential role in forming α-1, 6-glycosidic branching points, and determines the unique branching patterns in glycogen. Previously, evolutionary analysis of a small sets of GBEs based on their N-terminal domain organisation revealed that two types of GBEs might exist: 1) Type 1 GBE with both N1 and N2 (also known as CBM48) domains and 2) Type 2 GBE with only N2 domain. In this study, we initially analysed N-terminal domains of 169 manually reviewed bacterial GBEs based on hidden Markov models. A previously unreported group of GBEs (Type 3) with around 100 amino acids ahead of N1 domains was identified. Phylogenetic analysis found clustered patterns of GBE types in certain bacterial phyla, with the shorter, Type 2 GBEs predominantly found in Gram positive species, while longer Type 1 GBEs are found in Gram negative species. Several in vitro studies have linked N1 domain with transfer of short oligosaccharide chains during glycogen formation, which could lead to small and compact glycogen structures. Compact glycogen degrades more slowly and, as a result, may serve as a durable energy reserve, contributing to the enhanced environmental persistence for bacteria. We were therefore interested in classifying GBEs based on their N-termina...