title: Phylogenetic analysis reveals the evolution and diversification of cyclins in eukaryotes.
abstract: Cyclins are a family of diverse proteins that play fundamental roles in regulating cell cycle progression in Eukaryotes. Cyclins have been identified from protists to higher Eukaryotes, while its evolution remains vague and the findings turn out controversial. Current classification of cyclins is mainly based on their functions, which may not be appropriate for the systematic evolutionary analysis. In this work, we performed comparative and phylogenetic analysis of cyclins to investigate their classification, origin and evolution. Cyclins originated in early Eukaryotes and evolved from protists to plants, fungi and animals. Based on the phylogenetic tree, cyclins can be divided into three major groups designated as the group I, II and III with different functions and features. Group I plays key roles in cell cycle, group II varied in actions are kingdom (plant, fungi and animal) specific, and group III functions in transcription regulation. Our results showed that the dominating cyclins (group I) diverged from protists to plants, fungi and animals, while divergence of the other cyclins (groups II and III) has occurred in protists. We also discussed the evolutionary relationships between cyclins and cyclin-dependent kinases (CDKs) and found that the cyclins have undergone divergence in protists before the divergence of animal CDKs. This reclassification and evolutionary analysis of cyclins might facilitate understanding eukaryotic cell cycle control.
authors.affiliation: Hubei Bioinformatics & Molecular Imaging Key Laboratory, Department of Biomedical Engineering, College of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, Hubei 430074, PR China.
authors.forename: Zhaowu
authors.initials: Z
authors.lastname: Ma
authors.forename: Yuliang
authors.initials: Y
authors.lastname: Wu
authors.forename: Jialu
authors.initials: J
authors.lastname: Jin
authors.forename: Jun
authors.initials: J
authors.lastname: Yan
authors.forename: Shuzhen
authors.initials: S
authors.lastname: Kuang
authors.forename: Mi
authors.initials: M
authors.lastname: Zhou
authors.forename: Yuexuan
authors.initials: Y
authors.lastname: Zhang
authors.forename: An-Yuan
authors.initials: AY
authors.lastname: Guo
mesh_terms: D000595:Amino Acid Sequence; D001499:Bayes Theorem; D019295:Computational Biology; D016213:Cyclins / Q000145:classification* / Q000235:genetics*; D056890:Eukaryota / Q000235:genetics*; D019143:Evolution, Molecular; D014644:Genetic Variation; D016013:Likelihood Functions; D008957:Models, Genetic; D008969:Molecular Sequence Data; D010802:Phylogeny; D013045:Species Specificity
chemical_list: D016213:Cyclins