Evidence for an evolutionary relationship between Vmp1 and bacterial DedA proteins.

VMP1 and DedA proteins are conserved families of transmembrane proteins in eukaryotes and prokaryotes respectively. Despite numerous reports involving these proteins in multiple cellular processes, their molecular function is still unknown. They share the domain of unknown function PF09335, suggesting a possible functional relationship between these protein families. Here we show that VMP1 from different species contain two short motifs conserved in the bacterial DedA proteins and the yeast protein Tvp38. The hallmark of one of these motifs is a glycine residue previously shown to be strictly conserved in all the DedA proteins. Substitution of this residue to leucine, glutamate or arginine in Dictyostelium Vmp1 inactivates the protein, as shown by the inability of the mutants to rescue the phenotypes associated with the lack of Vmp1 including development and lipid homeostasis. This is the first experimental approach that supports an evolutionary relationship between Vmp1 and DedA proteins and highlights the importance of the conserved glycine residue in the PF09335 domain.