Analysis of Adaptive Evolution and Coevolution of L Gene in the Genus (Rhodophyta).

The adaptive evolution and coevolution of the ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit (L) gene in the genus were studied based on phylogenetic tree construction and the physicochemical properties and the secondary structures of protein encoded by L (Rubisco large subunit) were analyzed. The amino acids compositions and grand average of hydropathicity of freshwater and marine were similar. Rubisco large subunit of was hydrophilic and the secondary structure was primarily composed of α-helixes and β-sheets, revealing the relatively stable structure of this protein. The predicted phosphorylation sites in and were 33 and 36, respectively. No positive selection sites were detected in the genus , implying that L gene evolved either neutrally or under purifying selection. A total of 41 coevolutionary groups were detected in the Rubisco large subunit of and the coevolving sites are in closer proximity in 3-dimensional structure of the protein. Despite the long evolutionary history, L gene in genus under different environments is rather conservative.