The oxidation-state-dependent ATP-binding site of cytochrome c. A possible physiological significance

Abstract

Cytochrome c binds certain physiological anions that are known to modulate the biological properties of the protein, although it is not known whether this effect is fortuitous or has physiological significance. We have examined the ability of the protein and its semisynthetic analogues to associate with certain of these anions, e.g. ATP, ADP, Pi and citrate. Our results show that specific residues or clusters of residues on the surface of horse heart cytochrome c are involved in the recognition sites for these anions. We also observed that binding at one site is linked to the oxidation state of the protein.

Cell Respiration is Controlled by ATP, an Allosteric Inhibitor of Cytochrome‐c Oxidase

“…Secondly, the substrate pressure in the respiratory chain, and thus the ferro/ferricytochrome c ratio, affects mitochondrial respiration. This substrate control is further modulated by anions, in particular by the concentrations of ADP and ATP, which also bind to cytochrome c (Corthesy and Wallace, 1986) and modulate the rate of electron transfer from ferrocytochrome c to cytochrome-c oxidase (Craig and Wallace, 1995). Thirdly, the concentration of oxygen affects mitochondrial respiration, and fourthly, the matrix ATP/ADP ratio, as described in the present paper, results in allosteric feedback inhibition.…”

ATP Induces a Conformational Change in Lipid-bound Cytochrome c

“…A high affinity binding site for ATP has been described and shown to involve the invariant Arg 91 (5,(7)(8)(9)(10). The involvement of Arg 91 in binding of ATP and consequent modulation of electron transfer by the protein has been investigated previously by semisynthetic analogs of cyt c in which this single arginine residue of the 66 -104 peptide was chemically modified by cyclohexane-1,2-dione prior to ligation with the 1-65 peptide (10).…”

“…these effects are due to nucleotide binding to cyt c or to cyt c oxidase, or both remains unclear as both cyt c and cyt c oxidase have been shown to contain at least one nucleotide-binding site (5,6). In cyt c part of the high affinity ATP-binding site is constituted by the invariant Arg 91 (5,(7)(8)(9)(10), and binding of ATP to this decreases the rate of electron flow through the mitochondrial electron transport chain (9).…”

“…In cyt c part of the high affinity ATP-binding site is constituted by the invariant Arg 91 (5,(7)(8)(9)(10), and binding of ATP to this decreases the rate of electron flow through the mitochondrial electron transport chain (9). Accordingly, when the ATP-binding site of cyt c is occupied by a covalently bound ATP, the electron-transfer activity of cyt c with reductase and oxidase are inhibited to 41 and 11-15%, respectively, of the values measured for the native protein (3).…”

Definition of a Nucleotide Binding Site on Cytochrome c by Photoaffinity Labeling

“…More recently, gel filtration and equilibrium dialysis have indicated that ferroand ferricytochrome c bind two and three molecules of ATP, respectively, at low ionic strength (11,12), and both forms bind one at higher, closer to physiological, ionic strength (13). The binding of ATP is tighter than ADP.…”