TY - JOUR

T1 - Supramolecular structure of the OXPHOS system in highly thermogenic tissue of Arum maculatum

AU - Sunderhaus, Stephanie

AU - Klodmann, Jennifer

AU - Lenz, Christof

AU - Braun, Hans Peter

N1 - Funding information: We thank the “Berggarten” in Hannover, Germany, for providing Arum maculatum . Furthermore, we wish to thank Tom Elton, University of Nebraska, USA, for providing the antibodies directed against the AOX. This research was supported by the Deutsche Forschungsgemeinschaft (grants Br 1829/7-3 and Br 1829/8-1 ).

PY - 2010/1/22

Y1 - 2010/1/22

N2 - The protein complexes of the mitochondrial respiratory chain associate in defined ways forming supramolecular structures called respiratory supercomplexes or respirasomes. In plants, additional oxidoreductases participate in respiratory electron transport, e.g. the so-called "alternative NAD(P)H dehydrogenases" or an extra terminal oxidase called "alternative oxidase" (AOX). These additional enzymes were previously reported not to form part of respiratory supercomplexes. However, formation of respiratory supercomplexes might indirectly affect "alternative respiration" because electrons can be channeled within the supercomplexes which reduces access of the alternative enzymes towards their electron donating substrates. Here we report an investigation on the supramolecular organization of the respiratory chain in thermogenic Arum maculatum appendix mitochondria, which are known to have a highly active AOX for heat production. Investigations based on mild membrane solubilization by digitonin and protein separation by blue native PAGE revealed a very special organization of the respiratory chain in A. maculatum, which strikingly differs to the one described for the model plant Arabidopsis thaliana: (i) complex I is not present in monomeric form but exclusively forms part of a I + III2 supercomplex, (ii) the III2 + IV and I + III2 + IV supercomplexes are detectable but of low abundance, (iii) complex II has fewer subunits than in A. thaliana, and (iv) complex IV is mainly present as a monomer in a larger form termed "complex IVa". Since thermogenic tissue of A. maculatum at the same time has high AOX and I + III2 supercomplex abundance and activity, negative regulation of the alternative oxidase by supercomplex formation seems not to occur. Functional implications are discussed.

AB - The protein complexes of the mitochondrial respiratory chain associate in defined ways forming supramolecular structures called respiratory supercomplexes or respirasomes. In plants, additional oxidoreductases participate in respiratory electron transport, e.g. the so-called "alternative NAD(P)H dehydrogenases" or an extra terminal oxidase called "alternative oxidase" (AOX). These additional enzymes were previously reported not to form part of respiratory supercomplexes. However, formation of respiratory supercomplexes might indirectly affect "alternative respiration" because electrons can be channeled within the supercomplexes which reduces access of the alternative enzymes towards their electron donating substrates. Here we report an investigation on the supramolecular organization of the respiratory chain in thermogenic Arum maculatum appendix mitochondria, which are known to have a highly active AOX for heat production. Investigations based on mild membrane solubilization by digitonin and protein separation by blue native PAGE revealed a very special organization of the respiratory chain in A. maculatum, which strikingly differs to the one described for the model plant Arabidopsis thaliana: (i) complex I is not present in monomeric form but exclusively forms part of a I + III2 supercomplex, (ii) the III2 + IV and I + III2 + IV supercomplexes are detectable but of low abundance, (iii) complex II has fewer subunits than in A. thaliana, and (iv) complex IV is mainly present as a monomer in a larger form termed "complex IVa". Since thermogenic tissue of A. maculatum at the same time has high AOX and I + III2 supercomplex abundance and activity, negative regulation of the alternative oxidase by supercomplex formation seems not to occur. Functional implications are discussed.

KW - Alternative oxidase

KW - Arum maculatum

KW - Mitochondria

KW - Oxidative phosphorylation

KW - Respiratory supercomplexes

KW - Thermogenesis

UR - http://www.scopus.com/inward/record.url?scp=77949486574&partnerID=8YFLogxK

U2 - 10.15488/11662

DO - 10.15488/11662

M3 - Article

C2 - 20144873

AN - SCOPUS:77949486574

VL - 48

SP - 265

EP - 272

JO - Plant physiology and biochemistry

JF - Plant physiology and biochemistry

SN - 0981-9428

IS - 4

ER -