Computational Systems Biology Laboratory, Department of Biochemistry and Molecular Biology/Institute of Bioinformatics, University of Georgia, Athens, GA 30602-7229, USA.
Genomics Proteomics Bioinformatics. 2009 Dec;7(4):194-9. doi: 10.1016/S1672-0229(08)60049-2.
Cellulases are important glycosyl hydrolases (GHs) that hydrolyze cellulose polymers into smaller oligosaccharides by breaking the cellulose beta (1-->4) bonds, and they are widely used to produce cellulosic ethanol from the plant biomass. N-linked and O-linked glycosylations were proposed to impact the catalytic efficiency, cellulose binding affinity and the stability of cellulases based on observations of individual cellulases. As far as we know, there has not been any systematic analysis of the distributions of N-linked and O-linked glycosylated residues in cellulases, mainly due to the limited annotations of the relevant functional domains and the glycosylated residues. We have computationally annotated the functional domains and glycosylated residues in cellulases, and conducted a systematic analysis of the distributions of the N-linked and O-linked glycosylated residues in these enzymes. Many N-linked glycosylated residues were known to be in the GH domains of cellulases, but they are there probably just by chance, since the GH domain usually occupies more than half of the sequence length of a cellulase. Our analysis indicates that the O-linked glycosylated residues are significantly enriched in the linker regions between the carbohydrate binding module (CBM) domains and GH domains of cellulases. Possible mechanisms are discussed.
纤维素酶是一类重要的糖苷水解酶（GHs），能够通过切断纤维素β（1-4）糖苷键将纤维素聚合物水解成较小的寡糖，因此被广泛用于从植物生物质中生产纤维素乙醇。基于对个别纤维素酶的观察，人们提出 N 连接和 O 连接糖基化会影响其催化效率、纤维素结合亲和力和稳定性。据我们所知，由于相关功能域和糖基化残基的注释有限，尚未对纤维素酶中的 N 连接和 O 连接糖基化残基的分布进行任何系统分析。我们已经对纤维素酶中的功能域和糖基化残基进行了计算注释，并对这些酶中 N 连接和 O 连接糖基化残基的分布进行了系统分析。已知许多 N 连接糖基化残基位于纤维素酶的 GH 结构域中，但它们可能只是碰巧存在，因为 GH 结构域通常占据纤维素酶序列长度的一半以上。我们的分析表明，O 连接糖基化残基在纤维素酶的碳水化合物结合模块（CBM）结构域和 GH 结构域之间的连接区中明显富集。讨论了可能的机制。
