Evidence for Positive Selection in Ser/Thr Protein Kinases (STKs) Genes of Trichodesmium erythraeum

Ser/Thr protein kinases, members of signal transduction systems, play important roles in responses to the environmental changes and intra-cellular signals. In comparison with extensive literature describing the function, comprehensive evolutionary analyses of STK gene family are rare. In this study, we employed a maximum likelihood method to detect evidence of positive selection on STKs. Several site-models in the PAML package were used and identified 17 positive selected sites. Sites mostly likely undergoing positive selection were found in the additional domain suggesting these sites may play a major role in their functional divergence. We postulate that STK domain and additional domain have different evolutionary patterns. The sites identified to be under positive selection would provide targets for further structural and functional analyses.