Fig. 1.

Cysteine 786 of Opa1 is oxidized in hearts undergoing ischemia-reperfusion ex vivo.

(A) MS/MS spectra of the Opa1 peptide containing Cys786 from hearts subjected to ischemia-reperfusion injury bound to the thiopropyl Sepharose resin. Representative MS/MS spectra showing fragmentation of the NRTQEQCVHNETKNELEK peptide. The peptide sequence above the representative spectrum shows theoretical b ion identifications (red, N terminal fragments) and theoretical y ion identifications (blue, C terminal fragments). Peaks in the spectrum that are marked red correspond to matched b ions and peaks that are marked blue correspond to matched y ions. The number paired with each ion identification (i.e., b2, y4, etc.) indicates the number of amino acids present on N terminal fragments for b ions and C terminal fragments for y ions. This peptide identification was observed in hearts subjected to ischemia-reperfusion injury, not in control hearts at baseline.

(B) Predicted structural model of recombinant Opa1 protein, corresponding to Mus musculus isoform 1 (Uniprot: P58281), lacking the mitochondrial targeting sequence (MTS) and the transmembrane domain (TM). C-terminal cysteines are highlighted in red. Inset, close view of the Cys location in the stalk and PH domain of Opa1.

(C–E) Close views of Opa1 C-terminal cysteines and their surrounding residues: Cys786 (C), Cys583 and Cys586 (D), and Cys874 (E). (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)