title: The ζ subunit of the F1FO-ATP synthase of α-proteobacteria controls rotation of the nanomotor with a different structure.
abstract: The ζ subunit is a novel natural inhibitor of the α-proteobacterial F1FO-ATPase described originally in Paracoccus denitrificans. To characterize the mechanism by which this subunit inhibits the F1FO nanomotor, the ζ subunit of Paracoccus denitrificans (Pd-ζ) was analyzed by the combination of kinetic, biochemical, bioinformatic, proteomic, and structural approaches. The ζ subunit causes full inhibition of the sulfite-activated PdF1-ATPase with an apparent IC50 of 270 nM by a mechanism independent of the ε subunit. The inhibitory region of the ζ subunit resides in the first 14 N-terminal residues of the protein, which protrude from the 4-α-helix bundle structure of the isolated ζ subunit, as resolved by NMR. Cross-linking experiments show that the ζ subunit interacts with rotor (γ) and stator (α, β) subunits of the F1-ATPase, indicating that the ζ subunit hinders rotation of the central stalk. In addition, a putatively regulatory nucleotide-binding site was found in the ζ subunit by isothermal titration calorimetry. Together, the data show that the ζ subunit controls the rotation of F1FO-ATPase by a mechanism reminiscent of, but different from, those described for mitochondrial IF1 and bacterial ε subunits where the 4-α-helix bundle of ζ seems to work as an anchoring domain that orients the N-terminal inhibitory domain to hinder rotation of the central stalk.
authors: 1Universidad Nacional Autónoma de México (UNAM), Facultad de Química, Departamento de Biología, Circuito Escolar, s/n, Laboratorio 206, Edificio F, Ciudad Universitaria, Coyoacán, CP 04510, México, DF. jjgartre@unam.mx.
authors: Mariel
authors: M
authors: Zarco-Zavala
authors: Edgar
authors: E
authors: Morales-Ríos
authors: Guillermo
authors: G
authors: Mendoza-Hernández
authors: Leticia
authors: L
authors: Ramírez-Silva
authors: Gerardo
authors: G
authors: Pérez-Hernández
authors: José J
authors: JJ
authors: García-Trejo
mesh_terms: D000595:Amino Acid Sequence; D025243:Bacterial Proton-Translocating ATPases / Q000378:metabolism*; D001665:Binding Sites; D002151:Calorimetry; D003432:Cross-Linking Reagents; D007096:Imidoesters; D020128:Inhibitory Concentration 50; D007700:Kinetics; D008928:Mitochondria / Q000201:enzymology; D025261:Mitochondrial Proton-Translocating ATPases / Q000378:metabolism; D008969:Molecular Sequence Data; D010231:Paracoccus denitrificans / Q000201:enzymology*; D017434:Protein Structure, Tertiary; D021122:Protein Subunits / Q000378:metabolism; D012399:Rotation; D017386:Sequence Homology, Amino Acid; D013388:Succinimides
chemical_list: D003432:Cross-Linking Reagents; D007096:Imidoesters; D021122:Protein Subunits; D013388:Succinimides; C005905:methyl 4-mercaptobutyrimidate; C032180:dimethyl-3,3'-dithiobis-succinimidylpropionate; D025243:Bacterial Proton-Translocating ATPases; D025261:Mitochondrial Proton-Translocating ATPases
keywords: Paracoccus denitrificans; regulation