The global phylogeny of glycolytic enzymes.

Genes encoding the glycolytic enzymes of the facultative endocellular parasite Bartonella henselae have been analyzed phylogenetically within a very large cohort of homologues from bacteria and eukaryotes. We focus on this relative of Rickettsia prowazekii along with homologues from other alpha-proteobacteria to determine whether there have been systematic transfers of glycolytic genes from the presumed alpha-proteobacterial ancestor of the mitochondrion to the nucleus of the early eukaryote. The alpha-proteobacterial homologues representing the eight glycolytic enzymes studied here tend to cluster in well-supported nodes. Nevertheless, not one of these alpha-proteobacterial enzymes is related as a sister clade to the corresponding eukaryotic homologues. Nor is there a close phylogenetic relationship between glycolytic genes from Eucarya and any other bacterial phylum. In contrast, several of the reconstructions suggest that there may have been systematic transfer of sequences encoding glycolytic enzymes from cyanobacteria to some green plants. Otherwise, surprisingly little exchange between the bacterial and eukaryotic domains is observed. The descent of eukaryotic genes encoding enzymes of intermediary metabolism is reevaluated.