title: Physicochemical evolution and positive selection of the gymnosperm matK proteins.
abstract: It is not clear whether matK evolves under Darwinian selection. In this study, the gymnosperm Taxaceae, Cephalotaxaceae and Pinaceae were used to illustrate the physicochemical evolution, molecular adaptation and evolutionary dynamics of gene divergence in matKs. matK sequences were amplified from 27 Taxaceae and 12 Cephalotaxaceae species. matK sequences of 19 Pinaceae species were retrieved from GenBank. The phylogenetic tree was generated using conceptual-translated amino acid sequences. Selective influences were investigated using standard dN/dS ratio methods and more sensitive techniques investigating the amino acid property changes resulting from nonsynonymous replacements in a phylogenetic context. Analyses revealed the presence of positive selection in matKs (N-terminal region, RT domain and domain X) of Taxaceae and Pinaceae,and found positive destabilizing selection in N-terminal region and RT domain of Cephalotaxaceae matK. Moreover, various amino acid properties were found to be influenced by destabilizing positive selection. Amino acid sites relating to these properties and to different secondary structures were found and have the potential to affect group II intron maturase function. Despite the evolutionary constraint on the rapidly evolving matK, this protein evolves under positive selection in gymnosperm. Several regions of matK have experienced molecular adaptation which fine-tunes maturase performance.
authors.affiliation: Biotechnology Institute, College of Environment, Dalian Jiaotong University, Dalian 116028, People's Republic of China. hao@djtu.edu.cn
authors.forename: Da Cheng
authors.initials: da C
authors.lastname: Hao
authors.forename: Jun
authors.initials: J
authors.lastname: Mu
authors.forename: Shi Lin
authors.initials: SL
authors.lastname: Chen
authors.forename: Pei Gen
authors.initials: PG
authors.lastname: Xiao
mesh_terms: D000596:Amino Acids / Q000235:genetics; D001499:Bayes Theorem; D003062:Codon / Q000235:genetics; D032462:Cycadopsida / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics; D019143:Evolution, Molecular; D017343:Genes, Plant / Q000235:genetics; D016013:Likelihood Functions; D010802:Phylogeny; D010940:Plant Proteins / Q000235:genetics*; D012641:Selection, Genetic
chemical_list: D000596:Amino Acids; D003062:Codon; D018744:DNA, Plant; D010940:Plant Proteins