Comprehensive analyses of the cysteine thiol oxidation of PKM2 reveals the effects of multiple oxidation on cellular oxidative stress response

Abstract

Redox regulation of proteins via cysteine residue oxidation is known to be involved in the control of various cellular signal pathways. Pyruvate kinase M2 (PKM2), a rate-limiting enzyme in glycolysis, is critical for the metabolic shift from glycolysis to the pentose phosphate pathway under oxidative stress in cancer cell growth. The PKM2 tetramer acts as pyruvate kinase (PK), whereas the PKM2 dimer, which is induced by Cys358 oxidation, has reduced PK activity. Here, we identified four oxidation-sensitive cysteine residues (Cys152, Cys358, Cys423, and Cys424) responsible for three different oxidation forms. Possibly due to obstruction of the dimer-dimer interface, sulfenylation (-SOH) at Cys424 inhibited tetramer formation and PK activity. Cys423 is responsible for intermolecular disulfide bonds with heterologous proteins. In addition, intramolecular polysulfide linkage (-Sn-, n≧3) possible between Cys152 and Cys358 also is induced. We found that cells expressing the oxidation-resistant, constitutive-tetramer PKM2 (PKM2 C358,424A ) show a higher intracellular reactive oxygen species (ROS) and greater sensitivity to ROS-generating reagents and ROS-inducible anti-cancer drugs. These results highlight the possibility that PKM2 inhibition via Cys358 and Cys424 oxidation contributes to the elimination of excess ROS and oxidative stress.