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

Abstract

Vacuolar-type H+-translocating pyrophosphatases (V-PPases) have 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 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.