Positive selection adaptation of two-domain arginine kinase (AK) from cold seep Vesicomyidae clams
Arginine kinase (AK) is an important member of Phosphagen kinases which engage in energy metabolism process, and AKs from cold seep clams may develop an effective mechanism to adapt a special habitat (e.g. low temperature). Three Vesicomyidae clams and seven Veneridae clams (belong to the same Order Veneroida) were chosen to analyze the evolution of two-domain AKs. In the present study, ten two-domain AKs were identified and Neighbor-joining tree showed that AKs were divided into two groups. Branch-site model indicated that two-domain AKs were subjected to strong positive selection (ω2a = 17.5058). 16 positively selective sites were detected and five of them showed posterior probabilities of 0.95 or more. Comparative analysis found that domain 2 might be suffered from more evolutionary selection pressure than domain 1, as most positively sites were located at domain 2. Residue Pro (positively selective site) (587P in ApAK) in domain 2 from all Vesicomyidae AKs might participate in change of the synergism and in the function of its cold-adapted characteristics. In conclusion, our studies provide evidence of positive Darwinian selection in the two-domain AKs family of Vesicomyidae clams, and may contribute to a better understanding of its adaptation mechanisms to cold seep habitats.
KeywordsTwo-domain arginine kinases Cold seep Positive selection Vesicomyidae Veneridae
The authors thank Dr. Robert C. Vrijenhoek and Shannon B. Johnson for their help in sample collection. The authors thank Yanan Li and Jiawei Chen for their helpful comments. This work was supported by Strategic Priority Research Program of the Chinese Academy of Sciences (CAS) (XDB06010104), The National Key Research and Development Program of China (2017YFC0306600), Knowledge Innovation Program of CAS (SIDSSE–201401), Hundred Talents Program of CAS (SIDSSE–BR–201401), National Natural Science Foundation of China (41576127), and Major scientific and technological projects of Hainan Province (ZDKJ2016009).
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Conflict of interest
The authors declare that they have no conflict of interest.
All applicable international, national, and/or institutional guidelines for the care and use of animals were not followed.