ND3 Cys39 in complex I is exposed mitochondrial

• Mammalian complex I can adopt catalytically active (A-) or deactive (D-) states. A defining feature of the reversible transition between these two defined states is thought to be exposure of the ND3 subunit Cys39 residue in the D-state and its occlusion in the A-state. As the catalytic A/D transition is important in health and disease, we set out to quantify it by measuring Cys39 exposure using isotopic labeling and mass spectrometry, in parallel with complex I NADH/CoQ oxidoreductase activity. To our surprise, we found significant Cys39 exposure during NADH/CoQ oxidoreductase activity. Furthermore, this activity was unaffected if Cys39 alkylation occurred during complex I-linked respiration. In contrast, alkylation of catalytically inactive complex I irreversibly blocked the reactivation of NADH/CoQ oxidoreductase activity by NADH. Thus, Cys39 of ND3 is exposed in complex I during mitochondrial respiration, with significant implications for our understanding of the A/D transition and the mechanism of complex I.

Ämnesord

MEDICIN OCH HÄLSOVETENSKAP  -- Hälsovetenskap (hsv//swe)

MEDICAL AND HEALTH SCIENCES  -- Health Sciences (hsv//eng)

Nyckelord

active/de-active transition

s-nitrosation

superoxide-production

catalytic-properties

nadh

state

protein

membrane

translocation

respiration

Biochemistry & Molecular Biology

Publikations- och innehållstyp

ref (ämneskategori)

art (ämneskategori)