Functional interaction between complex I and mtNOS

IGLESIAS DE; BOMBICINO SS; ZAOBORNYJ T; BOVERIS A; VALDEZ LB

Kyoto

Congreso; 17th Biennial Meeting of Society for Free Radical Research International - SFRRI 2014; 2014

Society for Free Radical Research International

The aim of this work was to characterize the functional interaction between complex I and mtNOS using phosphorylating electron transfer particles (ETPH-Mg2+) from bovine heart, that expose NADH dehydrogenase and mtNOS to the surrounding medium. ETPH-Mg2+ particles reduced NAD+ -supported by reversed electron flow of the respiratory chain- at expenses of ATP when succinate was added. This activity was inhibited by the addition of antimycin (77%), rotenone (88%), oligomycin (98%) and m-CCCP (93%). ETPH-Mg2+ produced NO at a rate of 0.62±0.03 nmol/min.mg protein, supported by reversal electron flow. This production was still detectable in the absence of an exogenous electron donor (NADPH), suggesting that mtNOS activity could be sustained by electrons derived from the respiratory chain. Rotenone inhibited NO production (86%), but it did not inhibit the activity of isolated nNOS, suggesting that its effect is due to an electron flow inhibition and not to a direct action on mtNOS structure. Preliminary results showed that isolated complex I from bovine heart mitochondria is recognized by anti nNOS-antibodies. These data are in agreement with the reported physical interaction of mtNOS and complex I proteins (Franco et al., 2006). To conclude, mtNOS could functionally interacts with complex I proteins using electrons derived from the respiratory chain for its enzymatic activity