Codon usage patterns and adaptive evolution of marine unicellular cyanobacteria Synechococcus and Prochlorococcus

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• 作者：Tonghai Yu^a ; ¹ ; Jinsong Li^a ; ¹ ; Yang Yang^b ; Liu Qi^a ; Biaobang Chen^a ; Fangqing Zhao^c ; Qiyu Bao^a ; ^{baoqy@genomics.org.cn} ; Jinyu Wu^a ; ^{iamwujy@yahoo.com.cn}
• 关键词：Synechococcus ; Prochlorococcus ; Codon usage patterns ; Adaptive evolution
• 刊名：Molecular Phylogenetics and Evolution
• 出版年：2012
• 出版时间：January 2012
• 年：2012
• 卷：62
• 期：1
• 页码：206-213
• 全文大小：1698 K

文摘

Marine unicellular cyanobacteria, represented by Synechococcus and Prochlorococcus, dominate the total phytoplankton biomass and production in oligotrophic ocean. In this study, we employed comparative genomics approaches to extensively investigate synonymous codon usage bias and evolutionary rates in a large number of closely related species of marine unicellular cyanobacteria. Although these two groups of marine cyanobacteria have a close phylogenetic relationship, we find that they are highly divergent not only in codon usage patterns but also in the driving forces behind the diversification. It is revealed that in Prochlorococcus, mutation and genome compositional constraints are the main forces contributing to codon usage bias, whereas in Synechococcus, translational selection. In addition, nucleotide substitution rate analysis indicates that they are not evolving at a constant rate after the divergence and that the average d_N/d_S values of core genes in Synechococcus are significantly higher than those in Prochlorococcus. Our evolutionary genomic analysis provides the first insight into codon usage, evolutionary genetic mechanisms and environmental adaptation of Synechococcus and Prochlorococcus after divergence.