ND3, ND1 and 39 kDa subunits are more exposed in the de-active form of bovine mitochondrial complex I

Marion Babot, Paola Labarbuta, Amanda Birch, Sara Kee, Matthew Fuszard, Catherine H. Botting, Ilka Wittig, Heinrich Heide, Alexander Galkin

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Abstract

An intriguing feature of mitochondrial complex I from several species is the so-called A/D transition, whereby the idle enzyme spontaneously converts from the active (A) form to the de-active (D) form. The A/D transition plays an important role in tissue response to the lack of oxygen and hypoxic deactivation of the enzyme is one of the key regulatory events that occur in mitochondria during ischaemia. We demonstrate for the first time that the A/D conformational change of complex I does not affect the macromolecular organisation of supercomplexes in vitro as revealed by two types of native electrophoresis. Cysteine 39 of the mitochondrially-encoded ND3 subunit is known to become exposed upon de-activation. Here we show that even if complex I is a constituent of the I + III + IV (S) supercomplex, cysteine 39 is accessible for chemical modification in only the D-form. Using lysine-specific fluorescent labelling and a DIGE-like approach we further identified two new subunits involved in structural rearrangements during the A/D transition: ND1 (MT-ND1) and 39 kDa (NDUFA9). These results clearly show that structural rearrangements during de-activation of complex I include several subunits located at the junction between hydrophilic and hydrophobic domains, in the region of the quinone binding site. De-activation of mitochondrial complex I results in concerted structural rearrangement of membrane subunits which leads to the disruption of the sealed quinone chamber required for catalytic turnover.
Original languageEnglish
Pages (from-to)929-939
Number of pages11
JournalBiochimica et Biophysica Acta - Bioenergetics
Volume1837
Issue number6
Early online date21 Feb 2014
DOIs
Publication statusPublished - Jun 2014

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  • Projects

    R1342BSC: Role of mitochondrial complex 1 in cellular response in hypoxia

    Galkin, A.

    01/08/201031/03/2015

    Project: Research

    Cite this

    Babot, M., Labarbuta, P., Birch, A., Kee, S., Fuszard, M., Botting, C. H., Wittig, I., Heide, H., & Galkin, A. (2014). ND3, ND1 and 39 kDa subunits are more exposed in the de-active form of bovine mitochondrial complex I. Biochimica et Biophysica Acta - Bioenergetics, 1837(6), 929-939. https://doi.org/10.1016/j.bbabio.2014.02.013