古菌、细菌和真核生物纤维素酶的整体进化关系(英文)

Overall Evolutionary Relationship of Cellulases from Archaea,Bacteria and Eukaryota

【目的】纤维素酶在生物燃料、食品、造纸、制药和纺织工业应用广泛。许多生物都能产生纤维素酶,因此纤维素酶的进化关系非常复杂;加上人类用工程手段不断改造纤维素酶,使得纤维素酶的进化关系更加复杂化。因此,本研究对纤维素酶的整体进化关系进行大规模的系统发育和统计分析。【方法】选取来自116种古菌、1 744种细菌和556种真核生物的2 416种纤维素酶进行系统进化分析。通过计算平均成对p距离反映每个分类组中的序列差异;然后将差异分为组内差异和组间差异,从数值上反映基因的垂直转移和水平转移;最后,通过进化树展示基因转移的趋势。【结果】来自不同门、纲、目、科和属的纤维素酶,其氨基酸序列的平均成对p距离差异很大。在各个系统分类中,纤维素酶的组间差异和组内差异亦存在很大不同。大规模的系统发育分析显示,大多数纤维素酶的进化经历了不同的路径和分岔,并形成相互交织在一起的群簇。【结论】本研究从统计分析和系统发育的角度提供纤维素酶的整体进化关系,不仅包括纤维素酶基因的垂直遗传和水平转移,还包括多时间和多种属进化,展示了纤维素酶进化的全貌。统计分析不仅丰富系统发育的分析结果,还为利用生物技术设计所需要的纤维素酶提供补充信息。

【Objective】Cellulases have wide applications in biofuel,food,paper,pharmaceutical,and textile industries.Many organisms produce cellulases,therefore there is a very complicated evolutionary relationship for cellulases.Such a relationship is further tangled by the efforts that manipulate cellulase structures and express cellulase genes in different species to improve their activity and suitability.So far,no large-scale phylogenetic studies have been conducted to analyze the overall evolutionary relationship of cellulases.Yet no statistical studies have been conducted to exhaustively analyze variances of cellulases and their partitioned variances along taxonomic lineage from superkingdom to organism.【Methods】To fill these knowledge gaps,2 416 cellulases,including 116,1 744 and 556from archaea,bacteria and eukaryota,were studied using statistical and phylogenetic analyses.Statistical analysis was conducted by computing the average pairwise p?distance for each phylum,class,order,family and genus,and by further partitioning the variance into inter-clan variance and intraclan variance along taxonomic lineage.Large-scale phylogenetic analysis was performed through the phylogenetic tree of cellulases.【Results】The average pairwise p?distance of amino acid sequences varied greatly in the cellulases from different phylum,class,order,family and genus.The inter-clan variance and intra-clan variance varied also greatly along taxonomic lineage but a light pattern could be found in eukaryota.For large-scale phylogenetic analyses,most cellulases underwent different paths and bifurcations,and formed intertwined clusters,where many meaningful hints can be tracked.【Conclusion】This large-scale study provides the insights on overall evolutionary relationship of cellulases from both statistical and phylogenetic viewpoints.As additional information,the statistical analysis not only enriches the phylogeneticanalysis,but also suggests how to biotechnologically manipulate cellulases with desired qualities,and how the evolution of cellulases are involved with vertical inheritance,horizontal gene transfer,multiple times and multiple clans.