title: Crystal structure of subunits D and F in complex gives insight into energy transmission of the eukaryotic V-ATPase from Saccharomyces cerevisiae.
abstract: 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 Å resolution. Subunit D (ScD) consists of a long pair of α-helices connected by a short helix ((79)IGYQVQE(85)) as well as a β-hairpin region, which is flanked by two flexible loops. The long pair of helices is composed of the N-terminal α-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 β-strands (β1-β4) connected by four α-helices (α1-α4). α1 and β2 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 α-helix (α5). A perpendicular and extended conformation of helix α5 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.
authors.affiliation: From the School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Republic of Singapore.
authors.forename: Asha Manikkoth
authors.initials: AM
authors.lastname: Balakrishna
authors.affiliation: From the School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Republic of Singapore.
authors.forename: Sandip
authors.initials: S
authors.lastname: Basak
authors.affiliation: From the School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Republic of Singapore.
authors.forename: Malathy Sony Subramanian
authors.initials: MS
authors.lastname: Manimekalai
authors.affiliation: From the School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551, Republic of Singapore ggrueber@ntu.edu.sg.
authors.forename: Gerhard
authors.initials: G
authors.lastname: Grüber
mesh_terms: D000595:Amino Acid Sequence; D018360:Crystallography, X-Ray; D008969:Molecular Sequence Data; D055503:Protein Multimerization; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000737:chemistry; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry*; D025262:Vacuolar Proton-Translocating ATPases / Q000737:chemistry*
chemical_list: D021122:Protein Subunits; D029701:Saccharomyces cerevisiae Proteins; D025262:Vacuolar Proton-Translocating ATPases
keywords: ATP Synthase; Bioenergetics; Proton Pump; Saccharomyces cerevisiae; Vacuolar ATPase