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== Publication Abstract from PubMed ==
== Publication Abstract from PubMed ==
Subunit F of V-ATPases is proposed to undergo structural alterations during catalysis and reversible dissociation from the V1VO complex. Recently, we determined the low resolution structure of F from Saccharomyces cerevisiae V-ATPase, showing an N-terminal egg shape, connected to a C-terminal hook-like segment via a linker region. To understand the mechanistic role of subunit F of S. cerevisiae V-ATPase, composed of 118 amino acids, the crystal structure of the major part of F, F(1-94), was solved at 2.3 A resolution. The structural features were confirmed by solution NMR spectroscopy using the entire F subunit. The eukaryotic F subunit consists of the N-terminal F(1-94) domain with four-parallel beta-strands, which are intermittently surrounded by four alpha-helices, and the C terminus, including the alpha5-helix encompassing residues 103 to 113. Two loops (26)GQITPETQEK(35) and (60)ERDDI(64) are described to be essential in mechanistic processes of the V-ATPase enzyme. The (26)GQITPETQEK(35) loop becomes exposed when fitted into the recently determined EM structure of the yeast V1VO-ATPase. A mechanism is proposed in which the (26)GQITPETQEK(35) loop of subunit F and the flexible C-terminal domain of subunit H move in proximity, leading to an inhibitory effect of ATPase activity in V1. Subunits D and F are demonstrated to interact with subunit d. Together with NMR dynamics, the role of subunit F has been discussed in the light of its interactions in the processes of reversible disassembly and ATP hydrolysis of V-ATPases by transmitting movements of subunit d and H of the VO and V1 sector, respectively.
Eukaryotic V1VO-ATPases hydrolyze ATP in the V1 domain coupled to ion pumping in VO. A unique mode of regulation of V-ATPases is the reversible disassembly of V1 and VO, which reduces ATPase activity and causes silencing of ion conduction. The subunits D and F are proposed to be key in these enzymatic processes. Here, we describe the structures of two conformations of the subunit DF assembly of Saccharomyces cerevisiae (ScDF) V-ATPase at 3.1 A resolution. Subunit D (ScD) consists of a long pair of alpha-helices connected by a short helix ((79)IGYQVQE(85)) as well as a beta-hairpin region, which is flanked by two flexible loops. The long pair of helices is composed of the N-terminal alpha-helix and the C-terminal helix, showing structural alterations in the two ScDF structures. The entire subunit F (ScF) consists of an N-terminal domain of four beta-strands (beta1-beta4) connected by four alpha-helices (alpha1-alpha4). alpha1 and beta2 are connected via the loop (26)GQITPETQEK(35), which is unique in eukaryotic V-ATPases. Adjacent to the N-terminal domain is a flexible loop, followed by a C-terminal alpha-helix (alpha5). A perpendicular and extended conformation of helix alpha5 was observed in the two crystal structures and in solution x-ray scattering experiments, respectively. Fitted into the nucleotide-bound A3B3 structure of the related A-ATP synthase from Enterococcus hirae, the arrangements of the ScDF molecules reflect their central function in ATPase-coupled ion conduction. Furthermore, the flexibility of the terminal helices of both subunits as well as the loop (26)GQITPETQEK(35) provides information about the regulatory step of reversible V1VO disassembly.


Crystal and NMR structures give insights into the role and dynamics of subunit F of the eukaryotic V-ATPase from Saccharomyces cerevisiae.,Basak S, Lim J, Manimekalai MS, Balakrishna AM, Gruber G J Biol Chem. 2013 Apr 26;288(17):11930-9. doi: 10.1074/jbc.M113.461533. Epub 2013, Mar 8. PMID:23476018<ref>PMID:23476018</ref>
Crystal Structure of Subunits D and F in Complex Gives Insight into Energy Transmission of the Eukaryotic V-ATPase from Saccharomyces cerevisiae.,Balakrishna AM, Basak S, Manimekalai MS, Gruber G J Biol Chem. 2015 Feb 6;290(6):3183-96. doi: 10.1074/jbc.M114.622688. Epub 2014, Dec 12. PMID:25505269<ref>PMID:25505269</ref>


From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[ATPase|ATPase]]
== References ==
== References ==
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