Affiliation:
1. Department of Agricultural, Food and Nutritional Science University of Alberta 116 St and 85 Ave Edmonton Alberta T6G 2P5 Canada
2. Department of Biological Sciences University of Toronto Scarborough 1265 Military Trail Toronto Ontario M1C 1A4 Canada
3. Department of Molecular and Cellular Biology University of Guelph Guelph Ontario N1G 2W1 Canada
4. Agriculture and Agri‐Food Canada Lethbridge Research and Development Centre Lethbridge Alberta T1J 4B1 Canada
Abstract
SUMMARYPhosphatidylcholine has essential functions in many eukaryotic cells, and its de novo biosynthesis is rate‐limited by cytidine triphosphate:phosphocholine cytidylyltransferase (CCT). Although the biological and biochemical functions of CCT have been reported in mammals and several plants, this key enzyme has yet to be examined at a genome‐wide level. As such, certain fundamental questions remain unanswered, including the evolutionary history, genetic and functional relationships, and structural variations among CCTs in the green lineage. In the current study, in‐depth phylogenetic analysis, as well as the conservation and diversification in CCT gene structure and motif patterns, indicated that CCTs exist broadly in chlorophytes, bryophytes, lycophytes, monilophytes, gymnosperms, early‐diverging angiosperms, monocots, and eudicots, and form eight relatively conserved clades. To further explore the potential function of selection pressure, we conducted extensive selection pressure analysis with a representative CCT gene, CCT1 from the model plant Arabidopsis thaliana (AthCCT1), and identified two positive selection sites, L59 and Q156. Site‐directed mutagenesis and in vitro enzyme assays demonstrated that these positively selected sites were indeed important for the activity and substrate affinity of AthCCT1, and subsequent 3D structure analyses explained the potential biochemical mechanism. Taken together, our results unraveled the evolution and diversity of CCTs in the green lineage, as well as their association with the enzyme's biochemical and structural properties, and expanded our understanding of this important enzyme at the genome‐wide level.
Funder
China Scholarship Council
Natural Sciences and Engineering Research Council of Canada
Subject
Cell Biology,Plant Science,Genetics