title: Cysteine-reactive fluorescence probes of catalytic sites of ATP synthase.
abstract: We searched for new fluorescent probes of catalytic-site nucleotide binding in F(1)F(0)-ATP synthase by introducing Cys mutations at positions in or close to catalytic sites and then reacting Cys-mutant F(1) with thiol-reactive fluorescent probes. Four suitable mutant/probe combinations were identified. beta F410C labeled by 7-fluorobenz-2-oxa-1,3-diazole-4-sulfonamide (ABD-F) gave very large signal changes in response to nucleotide, allowing facile measurement of fluorescence and nucleotide-binding parameters, not only in F(1) but also in F(1)F(0). The results are consistent with the presence of three asymmetric catalytic sites of widely different affinities, with similar properties in both enzymes, and revealed a unique probe environment at the high-affinity site 1. beta Y331C F(1) labeled by ABD-F gave a large signal which monitored catalytic site polarity changes that occur along the ATP hydrolysis pathway. Two other mutant/probe combinations with significant nucleotide-responsive signals were beta Y331C labeled by 5-((((2-iodoacetyl)amino)ethyl)amino)naphthaline-1-sulfonic acid and alpha F291C labeled by 2-4'-(iodoacetamido)anilino)naphthalene-6-sulfonic acid. The signal of the latter responds differentially to nucleoside diphosphate versus triphosphate bound in catalytic sites.
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester Medical Center, Rochester, New York 14642, USA.
authors.forename: Joachim
authors.initials: J
authors.lastname: Weber
authors.forename: Vanesa
authors.initials: V
authors.lastname: Bijol
authors.forename: Susan
authors.initials: S
authors.lastname: Wilke-Mounts
authors.forename: Alan E
authors.initials: AE
authors.lastname: Senior
mesh_terms: D025181:ATP Synthetase Complexes / Q000737:chemistry* / Q000235:genetics; D000255:Adenosine Triphosphate / Q000378:metabolism; D001665:Binding Sites; D020134:Catalytic Domain; D003545:Cysteine / Q000737:chemistry*; D004305:Dose-Response Relationship, Drug; D004926:Escherichia coli / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry; D007700:Kinetics; D008274:Magnesium / Q000378:metabolism; D009154:Mutation; D009711:Nucleotides / Q000378:metabolism; D010100:Oxygen / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D013050:Spectrometry, Fluorescence / Q000379:methods
chemical_list: D005456:Fluorescent Dyes; D009711:Nucleotides; D000255:Adenosine Triphosphate; D025181:ATP Synthetase Complexes; D008274:Magnesium; D003545:Cysteine; D010100:Oxygen