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- Title
Cardiolipin deficiency causes a dissociation of the b c:caa megacomplex in B. subtilis membranes.
- Authors
García Montes de Oca, Led; Cabellos Avelar, Tecilli; Picón Garrido, Gerardo; Chagoya-López, Alicia; González de la Vara, Luis; Delgado Buenrostro, Norma; Chirino-López, Yolanda; Gómez-Lojero, Carlos; Gutiérrez-Cirlos, Emma
- Abstract
The associations among respiratory complexes in energy-transducing membranes have been established. In fact, it is known that the Gram-negative bacteria Paracoccus denitrificans and Escherichia coli have respiratory supercomplexes in their membranes. These supercomplexes are important for channeling substrates between enzymes in a metabolic pathway, and the assembly of these supercomplexes depends on the protein subunits and membrane lipids, mainly cardiolipin, which is present in both the mitochondrial inner membrane and bacterial membranes. The Gram-positive bacterium Bacillus subtilis has a branched respiratory chain, in which some complexes generate proton motive force whereas others constitute an escape valve of excess reducing power. Some peculiarities of this respiratory chain are the following: a type II NADH dehydrogenase, a unique b c complex that has a b type cytochrome with a covalently bound heme, and a c-type heme attached to the third subunit, which is similar to subunit IV of the photosynthetic b f complex. Cytochrome c oxygen reductase ( caa ) contains a c-type cytochrome on subunit I. We previously showed that the b c and the caa complexes form a supercomplex. Both the b c and the caa together with the quinol oxygen reductase aa generate the proton motive force in B. subtilis. In order to seek proof that this supercomplex is important for bacterial growth in aerobic conditions we compared the b c: caa supercomplex from wild type membranes with membranes from two mutants lacking cardiolipin. Both mutant complexes were found to have similar activity and heme content as the wild type. Clear native electrophoresis showed that mutants lacking cardiolipin had b c: caa supercomplexes of lower mass or even individual complexes after membrane solubilization with digitonin. The use of dodecyl maltoside revealed a more evident difference between wild-type and mutant supercomplexes. Here we provide evidence showing that cardiolipin plays a role in the stability of the b c: caa supercomplex in B. subtilis.
- Subjects
ESCHERICHIA coli enzymes; BACTERIAL genetics; ESCHERICHIA coli; MEMBRANE lipids; DEHYDROGENASE genetics; ESCHERICHIA coli growth
- Publication
Journal of Bioenergetics & Biomembranes, 2016, Vol 48, Issue 4, p451
- ISSN
0145-479X
- Publication type
Article
- DOI
10.1007/s10863-016-9671-y