A thermostable vacuolar-type membrane pyrophosphatase from the archaeon Pyrobaculum aerophilum:: implications for the origins of pyrophosphate-energized pumps

Vacuolar-type H+-translocating pyrophosphatases (V-PPases) hale been considered to be restricted to plants, a few species of phototrophic proteobacteria and protists. Here, we describe PVP, a thermostable, sequence-divergent V-PPase from the facultatively aerobic hyperthermophilic archaeon Pyrobaculum nel aerophilum. PVP shares only 38% sequence identity with both the prototypical V-PPase from Arabidopsis thaliana and the H+-PPi synthase from Rhodospirillum rubrum, yet possesses most of the structural features characteristic of V-PPases, Heterologous expression of PVP in Saccharomyces cerevisiae yields a M-r 64 000 membrane polypeptide that specifically catalyzes Mg2+-dependent PPi hydrolysis. The existence of PVP implies that PPi-energized H+-translocation is phylogenetically more deeply rooted than previously: thought, (C) 1999 Federation of European Biochemical Societies.