H+-translocating pyrophosphatase (H+-PPase)

H+-translocating pyrophosphatase (H+-PPase), also known as vacuolar H+-translocating pyrophosphatase, is a membrane-bound enzyme that couples the hydrolysis of inorganic pyrophosphate (PPi) to the active transport of protons across biological membranes [1, 5]. It is a unique type of proton pump, distinct from F-, P-, and V-type ATPases, and typically functions as a homodimer composed of a single 70-80 kDa polypeptide [5, 13]. The enzyme is primarily found in the vacuolar membranes of plants and the plasma or organellar membranes of various protozoa, bacteria, and archaea [1, 6]. In plants, it plays a dual role in acidifying the vacuole and maintaining low cytosolic PPi levels to prevent the inhibition of biosynthetic reactions [5, 15]. In parasitic protozoa like Plasmodium falciparum and Leishmania, H+-PPase is essential for maintaining intracellular pH and ion homeostasis [4]. Because H+-PPase is entirely absent in humans and fungi, it represents a promising target for the development of selective antiprotozoal drugs [4, 5]. Compounds such as bisphosphonates and their analogs have been shown to inhibit H+-PPase activity, effectively disrupting the bioenergetics of the parasite [4, 13]. Targeting this enzyme offers a strategy to combat drug-resistant strains of malaria and other neglected tropical diseases [4].

Other names

Vacuolar H+-translocating pyrophosphataseV-PPasemPPaseMembrane-bound inorganic pyrophosphatasePyrophosphate-energized vacuolar membrane proton pumpVHP1AVP1PfVP1

Inhibition of pyrophosphate hydrolysis and proton translocation, leading to disruption of intracellular pH homeostasis and accumulation of toxic levels of inorganic pyrophosphate.