5i1m
From Proteopedia
Yeast V-ATPase average of densities, a subunit segment
Structural highlights
Function[VPH1_YEAST] Subunit of the integral membrane V0 complex of vacuolar ATPase essential for assembly and catalytic activity. Is present only in vacuolar V-ATPase complexes. Enzymes containing this subunit have a 4-fold higher ratio of proton transport to ATP hydrolysis than complexes containing the Golgi/endosomal isoform and undergo reversible dissociation of V1 and V0 in response to glucose depletion. V-ATPase is responsible for acidifying a variety of intracellular compartments in eukaryotic cells.[1] [2] [3] Publication Abstract from PubMedRotary ATPases couple ATP synthesis or hydrolysis to proton translocation across a membrane. However, understanding proton translocation has been hampered by a lack of structural information for the membrane-embedded a subunit. The V/A-ATPase from the eubacteriumThermus thermophilusis similar in structure to the eukaryotic V-ATPase but has a simpler subunit composition and functions in vivo to synthesize ATP rather than pump protons. We determined theT. thermophilusV/A-ATPase structure by cryo-EM at 6.4 A resolution. Evolutionary covariance analysis allowed tracing of the a subunit sequence within the map, providing a complete model of the rotary ATPase. Comparing the membrane-embedded regions of theT. thermophilusV/A-ATPase and eukaryotic V-ATPase fromSaccharomyces cerevisiaeallowed identification of the alpha-helices that belong to the a subunit and revealed the existence of previously unknown subunits in the eukaryotic enzyme. Subsequent evolutionary covariance analysis enabled construction of a model of the a subunit in theS. cerevisaeV-ATPase that explains numerous biochemical studies of that enzyme. Comparing the two a subunit structures determined here with a structure of the distantly related a subunit from the bovine F-type ATP synthase revealed a conserved pattern of residues, suggesting a common mechanism for proton transport in all rotary ATPases. Models for the a subunits of the Thermus thermophilus V/A-ATPase and Saccharomyces cerevisiae V-ATPase enzymes by cryo-EM and evolutionary covariance.,Schep DG, Zhao J, Rubinstein JL Proc Natl Acad Sci U S A. 2016 Mar 22;113(12):3245-50. doi:, 10.1073/pnas.1521990113. Epub 2016 Mar 7. PMID:26951669[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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