ジャーナル: Proc Natl Acad Sci U S A / 年: 2016 タイトル: Models for the a subunits of the Thermus thermophilus V/A-ATPase and Saccharomyces cerevisiae V-ATPase enzymes by cryo-EM and evolutionary covariance. 著者: Daniel G Schep / Jianhua Zhao / John L Rubinstein / 要旨: Rotary 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 ...Rotary 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 eubacterium Thermus thermophilus is 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 the T. thermophilus V/A-ATPase structure by cryo-EM at 6.4 Å 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 the T. thermophilus V/A-ATPase and eukaryotic V-ATPase from Saccharomyces cerevisiae allowed identification of the α-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 the S. cerevisae V-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.
Six maps of the V-ATPase, averaged with the Vo regions aligned
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V-ATPase a subunit
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Segment of averaged densities from six maps of the V-ATPase, aligned to the a subunit. This does not contain the c ring or micelle, but has some densities that are not assigned to the a subunit and likely represent unknown subunits.
解像度: 7 Å / 解像度の算出法: OTHER / 粒子像の数: 269377 詳細: Resolution is approximated from the resolutions of the aligned and averaged maps that yielded the density. 対称性のタイプ: POINT