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

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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.