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Biochim Biophys Acta. 2014 Jun;1837(6):929-39. doi: 10.1016/j.bbabio.2014.02.013. Epub 2014 Feb 21.

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

Author information

1
Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK.
2
School of Chemistry, Biomedical Sciences Research Complex, BMS Annexe, University of St. Andrews, KY16 9ST, UK.
3
Functional Proteomics, SFB Core Unit, Faculty of Medicine, Goethe University Frankfurt, Theodor-Stern-Kai 7, 60590 Frankfurt am Main, Germany.
4
Queen's University Belfast, School of Biological Sciences, Medical Biology Centre, 97 Lisburn Road, Belfast BT9 7BL, UK. Electronic address: a.galkin@qub.ac.uk.

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+III2+IV (S1) 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 39kDa (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.

KEYWORDS:

A/D transition; Complex I; Conformational change; N-hydroxysuccinimide; NADH:ubiquinone oxidoreductase; Protein tyrosine modification

PMID:
24560811
PMCID:
PMC4331043
DOI:
10.1016/j.bbabio.2014.02.013
[Indexed for MEDLINE]
Free PMC Article

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