Characterization of the interaction between human cytochrome c and transfer RNAphe

Cytochrome <i>c</i> (cyt <i>c</i>) 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 <i>c</i>, impeding the formation of the apoptosome complex and thereby suppressing apoptosis. To elucidate the molecular mechanism underlying the interaction between cyt <i>c</i> and tRNA, nuclear magnetic resonance (NMR)-based chemical shift perturbation and intensity analysis were employed to characterize the binding interface between cyt <i>c</i> and tRNA^phe. The findings demonstrate that cyt <i>c</i> primarily engages with tRNA^phe through its 70-85 Ω-loop and <i>N</i>-terminal α-helix. This interaction sterically hinders the accessibility of small molecules, such as H₂O₂, to the hydrophobic pocket of cyt <i>c</i>, consequently attenuating its peroxidase activity. Furthermore, oxidative modification of cyt <i>c</i>, particularly the carbonylation of positively charged lysine residues, weakens this interaction.