Function, structure and regulation of the vacuolar (H+)-ATPases

Department of Physiology, Tufts University School of Medicine, 136 Harrison Avenue, Boston, MA 02111, USA.
Archives of Biochemistry and Biophysics (Impact Factor: 3.02). 09/2008; 476(1):33-42. DOI: 10.1016/
Source: PubMed


The vacuolar ATPases (or V-ATPases) are ATP-driven proton pumps that function to both acidify intracellular compartments and to transport protons across the plasma membrane. Intracellular V-ATPases function in such normal cellular processes as receptor-mediated endocytosis, intracellular membrane traffic, prohormone processing, protein degradation and neurotransmitter uptake, as well as in disease processes, including infection by influenza and other viruses and killing of cells by anthrax and diphtheria toxin. Plasma membrane V-ATPases are important in such physiological processes as urinary acidification, bone resorption and sperm maturation as well as in human diseases, including osteopetrosis, renal tubular acidosis and tumor metastasis. V-ATPases are large multi-subunit complexes composed of a peripheral domain (V(1)) responsible for hydrolysis of ATP and an integral domain (V(0)) that carries out proton transport. Proton transport is coupled to ATP hydrolysis by a rotary mechanism. V-ATPase activity is regulated in vivo using a number of mechanisms, including reversible dissociation of the V(1) and V(0) domains, changes in coupling efficiency of proton transport and ATP hydrolysis and changes in pump density through reversible fusion of V-ATPase containing vesicles. V-ATPases are emerging as potential drug targets in treating a number of human diseases including osteoporosis and cancer.

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    • "Most fungal V-ATPase subunits are encoded by a single gene; the Voa subunit is the only subunit encoded by two isoforms. Mammalian V-ATPases are strikingly different, with seven different subunits displaying isoform variation (Jefferies et al., 2008; Figure 1). This drastic difference between fungi and mammals could be exploited for fungal-specific drug development. "
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    ABSTRACT: Vacuolar proton-translocating ATPase (V-ATPase) is a membrane-bound, multi-subunit enzyme that uses the energy of ATP hydrolysis to pump protons across membranes. V-ATPase activity is critical for pH homeostasis and organelle acidification as well as for generation of the membrane potential that drives secondary transporters and cellular metabolism. V-ATPase is highly conserved across species and is best characterized in the model fungus Saccharomyces cerevisiae. However, recent studies in mammals have identified significant alterations from fungi, particularly in the isoform composition of the 14 subunits and in the regulation of complex disassembly. These differences could be exploited for selectivity between fungi and humans and highlight the potential for V-ATPase as an anti-fungal drug target. Candida albicans is a major human fungal pathogen and causes fatality in 35% of systemic infections, even with anti-fungal treatment. The pathogenicity of C. albicans correlates with environmental, vacuolar, and cytoplasmic pH regulation, and V-ATPase appears to play a fundamental role in each of these processes. Genetic loss of V-ATPase in pathogenic fungi leads to defective virulence, and a comprehensive picture of the mechanisms involved is emerging. Recent studies have explored the practical utility of V-ATPase as an anti-fungal drug target in C. albicans, including pharmacological inhibition, azole therapy, and targeting of downstream pathways. This overview will discuss these studies as well as hypothetical ways to target V-ATPase and novel high-throughput methods for use in future drug discovery screens.
    Frontiers in Pharmacology 01/2014; 5:4. DOI:10.3389/fphar.2014.00004 · 3.80 Impact Factor
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    • "V-ATPases are highly conserved ATP-dependent proton pumps that play a universal role as pH regulators in intracellular acidic organelles of eukaryotic cells. They form multi-subunit complexes assembled in two subdomains: the Vo membrane domain, which is responsible for proton transport across membranes and is comprised of the subunits a, d, c, c″, and e; and the V1 cytoplasmic domain, which is responsible for ATP hydrolysis and is made up of 8 subunit types, designated as A to H. Intracellular V-ATPases play essential roles in receptor-mediated endocytosis, vesicular trafficking between organelles, membrane fusion, protein degradation and autophagy123. In addition to their role in intracellular compartments, V-ATPases can also pump protons across the plasma membrane, thus acidifying the extracellular medium. "
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    ABSTRACT: Vacuolar-type H(+) ATPases (V-ATPases) are multimeric protein complexes that play a universal role in the acidification of intracellular compartments in eukaryotic cells. We have isolated the recessive medaka mutation tintachina (tch), which carries an inactivating modification of the conserved glycine residue (G75R) of the proton pump subunit atp6v1Ba/vatB1. Mutant embryos show penetrant pigmentation defects, massive brain apoptosis and lethality before hatching. Strikingly, an equivalent mutation in atp6v1B1 (G78R) has been reported in a family of patients suffering from distal renal tubular acidosis (dRTA), a hereditary disease that causes metabolic acidosis due to impaired kidney function. This poses the question as to how molecularly identical mutations result in markedly different phenotypes in two vertebrate species. Our work offers an explanation for this phenomenon. We propose that, after successive rounds of whole-genome duplication, the emergence of paralogous copies allowed the divergence of the atp6v1B cis-regulatory control in different vertebrate groups.
    Scientific Reports 11/2013; 3:3217. DOI:10.1038/srep03217 · 5.58 Impact Factor
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    • "The V-ATPase pump plays an essential role in nutrient uptake and ion balance in the insect gut system [20]. The V-ATPase holoenzyme functions by hydrolyzing an ATP molecule to ADP and phosphate and using this generated energy to pump protons across plasma membranes to regulate pH in various intracellular compartments [21]. V-ATPase is composed of two functional domains, V1 and V0. "
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    ABSTRACT: The corn planthopper, Peregrinus maidis, is a major pest of agronomically-important crops. Peregrinus maidis has a large geographical distribution and transmits Maize mosaic rhabdovirus (MMV) and Maize stripe tenuivirus (MSpV). The objective of this study was to develop effective RNAi methods for P. maidis. Vacuolar-ATPase (V-ATPase) is an essential enzyme for hydrolysis of ATP and for transport of protons out of cells thereby maintaining membrane ion balance, and it has been demonstrated to be an efficacious target for RNAi in other insects. In this study, two genes encoding subunits of P. maidis V-ATPase (V-ATPase B and V-ATPase D) were chosen as RNAi target genes. The open reading frames of V-ATPase B and D were generated and used for constructing dsRNA fragments. Experiments were conducted using oral delivery and microinjection of V-ATPase B and V-ATPase D dsRNA to investigate the effectiveness of RNAi in P. maidis. Real-time quantitative reverse transcriptase-PCR (qRT-PCR) analysis indicated that microinjection of V-ATPase dsRNA led to a minimum reduction of 27-fold in the normalized abundance of V-ATPase transcripts two days post injection, while ingestion of dsRNA resulted in a two-fold reduction after six days of feeding. While both methods of dsRNA delivery resulted in knockdown of target transcripts, the injection method was more rapid and effective. The reduction in V-ATPase transcript abundance resulted in observable phenotypes. Specifically, the development of nymphs injected with 200 ng of either V-ATPase B or D dsRNA was impaired, resulting in higher mortality and lower fecundity than control insects injected with GFP dsRNA. Microscopic examination of these insects revealed that female reproductive organs did not develop normally. The successful development of RNAi in P. maidis to target specific genes will enable the development of new insect control strategies and functional analysis of vital genes and genes associated with interactions between P. maidis and MMV.
    PLoS ONE 08/2013; 8(8):e70243. DOI:10.1371/journal.pone.0070243 · 3.23 Impact Factor
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