Structure and regulation of the vacuolar ATPases

Abstract

The vacuolar (H(+))-ATPases (V-ATPases) are ATP-dependent proton pumps responsible for both acidification of intracellular compartments and, for certain cell types, proton transport across the plasma membrane. Intracellular V-ATPases function in both endocytic and intracellular membrane traffic, processing and degradation of macromolecules in secretory and digestive compartments, coupled transport of small molecules such as neurotransmitters and ATP and in the entry of pathogenic agents, including envelope viruses and bacterial toxins. V-ATPases are present in the plasma membrane of renal cells, osteoclasts, macrophages, epididymal cells and certain tumor cells where they are important for urinary acidification, bone resorption, pH homeostasis, sperm maturation and tumor cell invasion, respectively. The V-ATPases are composed of a peripheral domain (V(1)) that carries out ATP hydrolysis and an integral domain (V(0)) responsible for proton transport. V(1) contains eight subunits (A-H) while V(0) contains six subunits (a, c, c', c'', d and e). V-ATPases operate by a rotary mechanism in which ATP hydrolysis within V(1) drives rotation of a central rotary domain, that includes a ring of proteolipid subunits (c, c' and c''), relative to the remainder of the complex. Rotation of the proteolipid ring relative to subunit a within V(0) drives active transport of protons across the membrane. Two important mechanisms of regulating V-ATPase activity in vivo are reversible dissociation of the V(1) and V(0) domains and changes in coupling efficiency of proton transport and ATP hydrolysis. This review focuses on recent advances in our lab in understanding the structure and regulation of the V-ATPases.

Estimating the rotation rate in the vacuolar proton-ATPase in native yeast vacuolar membranes

“…The proton-translocating adenosine-triphosphatase (first observed in vacuolar membranes, hence called vacuolar proton-ATPase or V-ATPase) is nature's most universal proton pump found in all eukaryots (Finbow and Harrison 1997;Nishi and Forgac 2002;Cipriano et al 2008;Jefferies et al 2008). Similarly to the more familiar and related F-ATP synthase (FATPase) there are 3 catalytic sites, here for ATP hydrolysis, in the water soluble V 1 domain (F 1 domain in F-ATPase), and trans-membrane proton transport takes places in hydrophilic channels (or sacks) in the interface between the "c ring" and subunit a of the membrane bound V o (F o ) domain (Wilkens et al 1999;Grabe et al 2000;KawasakiNishi et al 2001;Wang et al 2004;Beyenbach and Wieczorek 2006) (Fig.…”

“…In the case of V-ATPase rotation is driven by ATP binding and hydrolysis. One ATP molecule drives a 120 degrees rotation of the rotor and a transport of two protons from the cytoplasmic side to the "other" side, which can be the lumen of intracellular organs or the extracellular space, depending on the cellular location of V-ATPase (Finbow and Harrison 1997;Nishi and Forgac 2002;Beyenbach and Wieczorek 2006;Cipriano et al 2008;Jefferies et al 2008). This stoichiomerty is different form that of F-ATPase, in which there are ~12 c subunits, which have only 2 trans-membrane helices, each with a unique glutamic acid.…”

Quantitative Proteomics of the Tonoplast Reveals a Role for Glycolytic Enzymes in Salt Tolerance

“…Transport of sodium across the vacuolar membrane (tonoplast) is attributed to members of the family of Na + /H + exchangers (NHXs) and is driven by the inside acidic pH gradient generated by the vacuolar H + -ATPase (V-ATPase). While NHX proteins are encoded by single polypeptides, the V-ATPase is a multisubunit enzyme composed of at least 13 subunits, organized to form two distinct sectors: a peripheral domain (V 1 ) and a membrane domain (V o ) (Cipriano et al, 2008). VHA subunits A, B, C, D, E, F, G, and H make up the V 1 sector, and subunits a, b, c, d, and e compose the V o sector (Cipriano et al, 2008).…”

“…While NHX proteins are encoded by single polypeptides, the V-ATPase is a multisubunit enzyme composed of at least 13 subunits, organized to form two distinct sectors: a peripheral domain (V 1 ) and a membrane domain (V o ) (Cipriano et al, 2008). VHA subunits A, B, C, D, E, F, G, and H make up the V 1 sector, and subunits a, b, c, d, and e compose the V o sector (Cipriano et al, 2008). In both salt-tolerant halophytes and salt-sensitive glycophytes, sodium regulates the expression at the transcript and protein levels for the tonoplast NHXs (Shi and Zhu, 2002;Yokoi et al, 2002) and different subunits of the V-ATPase Tsiantis et al, 1996;Dietz et al, 2001;Vera-Estrella et al, 2005).…”

A pivotal role of phosphatidylinositol 3-kinase in delaying of methyl jasmonate-induced leaf senescence

“…The major mechanism of V-ATPase regulation is the reversible assembly/disassembly of the V0 and V1 sectors. 3 In renal epithelial cells induced with glucose, phosphoinositide 3-kinase type I (PI3K) promotes the assembly and translocation of VATPase. 4 PI3K activated by influenza A virus also interacts with the subunit E of the V1 domain of V-ATPase.…”