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Báo cáo khoa học: Functional transitions of F0F1-ATPase mediated by the inhibitory peptide IF1 in yeast coupled submitochondrial particles

The mechanism of inhibition of yeast F0F1-ATPase by its naturally occurring protein inhibitor (IF1) was investi-gated in submitochondrial particles by studying the IF1-mediatedATPase inhibition in the presence andabsence of a protonmotive force. In the presence of protonmotive force, IF1 added during net NTP hydrolysis almost completely inhibitedNTPase activity. At moderate IF1 concentration, subsequent uncoupler addition unexpect-edly caused a burst of NTP hydrolysis. | Eur. J. Biochem. 271 1963-1970 2004 FEBS 2004 doi 10.1111 j.1432-1033.2004.04108.x Functional transitions of F0F1-ATPase mediated by the inhibitory peptide IF1 in yeast coupled submitochondrial particles Mikhail Galkin1 I Renee Venard1 Jacques Vaillier2 Jean Velours2 and Francis Haraux1 1 Service de Bioénergétique CNRS-URA 2096 Gif-sur-Yvette France 2Institut de Biochimie et Génétique Cellulaires du CNRS Bordeaux France The mechanism of inhibition of yeast F0F1-ATPase by its naturally occurring protein inhibitor IF1 was investigated in submitochondrial particles by studying the IF1-mediatedATPase inhibition in the presence andabsence of a protonmotive force. In the presence of protonmotive force IF1 added during net NTP hydrolysis almost completely inhibited NPPase activity. At moderate 1F1 concentration subsequent uncoupler addition unexpectedly caused a burst of NTP hydrolysis. We propose that the protonmotive force induces the conversion of IF1-inhibited F0F1-ATPase into a new form having a lower affinity for IF1. This form remains inactive for ATP hydrolysis after IF1 release. Uncoupling simultaneously releases ATP hydrolysis and converts the latent form of IF1-free F0F1-ATPase back to the active form. The relationship between the different steps of the catalytic cycle the mechanism of inhibition by IF1 andthe interconversion process is discussed. Keywords ATP synthase catalytic state inhibitory peptide latent ATPase protonmotive force yeast. Energy-driven ATP synthesis in energy-transducing membranes is carried out by memraane-bondd F0FrATPase complex or ATP synthase 1 . The extrinsic F1 subcomplex is composed of fwe ỵpees of subunits in the ttoichiomurty a3p3yỗE. Three fast-exchangeable nucleotide-binding sites presumably catalytic andthree slow-exchangeable nucleotide-binding sites certainly noncatalytic reside in a b interfaces 2 3 an alternative point of view can be found in 4 . The membranous F0 subcomplex promotes proton translocation energetically .