Substrate Binding-Induced Alteration of Nucleotide Binding Site Properties ofChloroplast Coupling Factor

摘要

Two adenine nucleotide binding sites of chloroplast coupling factor 1 (CF1) wereshown previously to switch their properties after exposure of the enzyme to Mg2+-ATP or Ca2+-ATP (Shapiro, A.B., and McCarty, R.E. (1988) J. Biol. Chem. 263, 14160-14165). The change in binding properties was monitored by fluorescence resonance energy transfer between Lucifer Yellow vinyl sulfone covalently bound to one alpha subunit and trinitrophenyl-ATP (TNP-ATP) tightly bound to nucleotide binding site 1. When the nucleotide binding properties of sites 1 and 3 switch during catalysis, site 3, which is nearer Lucifer Yellow than site 1, allowing TNP-ATP to become tightly bound near Lucifer Yellow. The smaller separation allows energy transfer to occur, resulting in decreased Lucifer Yellow fluorescence. (jes)