Genomics and evolution of eukaryotic phospholipid biosynthesis

Abstract

Phospholipid biosynthetic enzymes produce diverse molecular structures and they are often present in multiple forms encoded by different genes. This work utilizes comparative genomics and phylogenetics to explore the distribution, structure and evolution of phospholipid biosynthetic genes and pathways in 26 eukaryotic genomes. The emerging picture indicates that, although the basic pathway structure was formed early in eukaryotic evolution, individual enzyme families followed unique evolutionary trajectories. Choline and ethanolamine kinases and cytidylyltransferases emerged in ancestral eukaryotes whereas the corresponding phosphatidyltransferases evolved mainly in a lineage specific manner. Several unicellular eukaryotes maintain bacterial-type enzymes and reactions for the synthesis of phosphatidylglycerol and cardiolipin. Base-exchange phosphatidylserine synthases are widespread and ancestral enzymes. The multiplicity of phospholipid biosynthetic enzymes has been largely generated by gene expansion in a lineage specific manner. These observations suggest that phospholipid biosynthesis has been an actively evolving system. Furthermore, genomic analysis indicates the existence of novel phosphatidyltransferases and provides a candidate for the uncharacterized eukaryotic phosphatidylglycerol phosphate phosphatase.