Characterization of the interaction between human cytochrome c and transfer RNA^phe

Cytochrome c (cyt c) is released from mitochondria into the cytosol upon apoptotic stimulation, ultimately triggering programmed cell death. Recent studies have revealed that transfer RNA (tRNA) interacts with cyt c, impeding the formation of the apoptosome complex and thereby suppressing apoptosis. To elucidate the molecular mechanism underlying the interaction between cyt c and tRNA, nuclear magnetic resonance (NMR)-based chemical shift perturbation and intensity analysis were employed to characterize the binding interface between cyt c and tRNA^phe. The findings demonstrate that cyt c primarily engages with tRNA^phe through its 70-85 Ω-loop and N-terminal α-helix. This interaction sterically hinders the accessibility of small molecules, such as H₂O₂, to the hydrophobic pocket of cyt c, consequently attenuating its peroxidase activity. Furthermore, oxidative modification of cyt c, particularly the carbonylation of positively charged lysine residues, weakens this interaction.