Evolutionary Ancestry of Eukaryotic Protein Kinases and Choline Kinases
Shenshen Lai, Javad Safaei and Steven Pelech*
+ Author Affiliations
University of British Columbia, Canada
↵* Corresponding author; email: email@example.com
Author contributions: SP conceived the project. SL and SP designed and performed most of the analyses. JS carried out the pfam domain alignments and kinase domain evolutionary conservation analyses. SL wrote the initial draft of the manuscript and SP completed the final version. SL and SP prepared the figures and tables. All authors analyzed the results and approved the final version of the manuscript.
The reversible phosphorylation of proteins catalyzed by protein kinases in eukaryotes supports an important role for eukaryotic protein kinases (ePKs) in the emergence of nucleated cells in the third superkingdom of life. Choline kinases (ChKs) could also be critical in the early evolution of eukaryotes, because of their function in the biosynthesis of phosphatidylcholine, which is unique to eukaryotic membranes. However, the genomic origins of ePKs and ChKs are unclear. The high degeneracy of protein sequences and broad expansion of ePK families have made this fundamental question difficult to answer. In this study, we identified two class-I aminoacyl-tRNA synthetases with high similarities to consensus amino acid sequences of human protein-serine/threonine kinases. Comparisons of primary and tertiary structures supported that ePKs and ChKs evolved from a common ancestor related to glutaminyl aminoacyl-tRNA synthetases, which may have been one of the key factors in the successful of emergence of ancient eukaryotic cells from bacterial colonies.
aminoacyl tRNA synthetase protein evolution protein kinase protein phosphorylation signal transduction choline kinase glutaminyl aminoacyl tRNA synthetase phosphatidylcholine biosynthesis
Received September 10, 2015. Accepted January 7, 2016.
Copyright © 2016, The American Society for Biochemistry and Molecular Biology
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