Internal Architecture of Mitochondrial Complex I from Arabidopsis thaliana

Abstract

The NADH dehydrogenase complex (complex I) of the respiratory chain has unique features in plants. It is the main entrance site for electrons into the respiratory electron transfer chain, has a role in maintaining the redox balance of the entire plant cell and additionally comprises enzymatic side activities essential for other metabolic pathways. Here, we present a proteomic investigation to elucidate its internal structure. Arabidopsis thaliana complex I was purified by a gentle biochemical procedure that includes a cytochrome c-mediated depletion of other respiratory protein complexes. To examine its internal subunit arrangement, isolated complex I was dissected into subcomplexes. Controlled disassembly of the holo complex (1000 kD) by low-concentration SDS treatment produced 10 subcomplexes of 550, 450, 370, 270, 240, 210, 160, 140, 140, and 85 kD. Systematic analyses of subunit composition by mass spectrometry gave insights into subunit arrangement within complex I. Overall, Arabidopsis complex I includes at least 49 subunits, 17 of which are unique to plants. Subunits form subcomplexes analogous to the known functional modules of complex I from heterotrophic eukaryotes (the so-called N-, Q-, and P-modules), but also additional modules, most notably an 85-kD domain including g-type carbonic anhydrases. Based on topological information for many of its subunits, we present a model of the internal architecture of plant complex I.

Respiratory-deficient mutants of the unicellular green alga Chlamydomonas: A review

“…This suggests that ND4, ND5 and PSDW, on one hand, and ND1, ND3, ND4L, and ND6, on the other hand, are located in two different membrane domains of the complex I membrane arm. This hypothesis is in good agreement with structural models proposed for the localization of these subunits within for example Arabidopsis [9] or bovine complex I [49].…”

“…5 roles in regulation, protection against reactive oxygen species, assembly and stability [7]. In Arabidopsis, green algae and amoebozoa, subunits structurally related to gamma carbonic anhydrases have been found [6,8,9]. Single particle electron microscopy analyzes of complex I from Polytomella (a chloroplast-less and close relative of Chlamydomonas), A. thaliana, Zea mays and Solanum tuberosum indicate that these γ-CA subunits could constitute a spherical domain attached to the central part of the membrane arm of complex I, and exposed to the matrix (Fig.…”

The mitochondrial respiratory chain of the secondary green alga Euglena gracilis shares many additional subunits with parasitic Trypanosomatidae

“…Although we cannot completely rule out the possibility that DNAJ/HSP40 and G3PD are non-mitochondrial contaminations of the mitochondrial fraction (see section 3 of Materials and Methods), our study brings evidence of a potential interaction between this cohort of proteins and respiratory CI. We recently proposed that some proteins might use CI as an anchoring point and that these interactions might be rather specific to limited groups or species (Cardol, 2011): acyl carrier protein (NDUFAB1/ACPM) and deoxyribonucleoside kinase-like subunit (NDUFA10/42 kDa) in mammals, galactono-lactone dehydrogenase in land plants (Klodmann et al, 2010), or rhodanese in Y. lipolytica (Angerer et al, 2011). Similarly, G3PD and DNAJ could be specifically associated with CI in E. gracilis.…”

iTRAQ Protein Profile Analysis of Arabidopsis Roots Reveals New Aspects Critical for Iron Homeostasis

“…Five proteins functioning in respiration, the cytochrome c oxidase At4g21105, the ubiquinol-cytochrome c reductase complex ubiquinone-binding protein At3g10860, and three components of mitochondrial complex I, At2g27730, At2g47690, and At4g20150 (Klodmann et al, 2010), showed increased abundance under Fe-deficient conditions (Table I; Fig. 4).…”