title: Cardiolipin deficiency causes a dissociation of the b 6 c:caa 3 megacomplex in B. subtilis membranes.
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 6 c complex that has a b 6 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 6 f complex. Cytochrome c oxygen reductase (caa 3 ) contains a c-type cytochrome on subunit I. We previously showed that the b 6 c and the caa 3 complexes form a supercomplex. Both the b 6 c and the caa 3 together with the quinol oxygen reductase aa 3 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 6 c: caa 3 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 6 c:caa 3 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 6 c:caa 3 supercomplex in B. subtilis.
authors: Biochemistry and Bioenergetics Laboratory, Unidad de Biomedicina, F.E.S. Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios #1, Los Reyes Iztacala, c.p. 54090, Tlalnepantla, Estado de México, Mexico.
authors: Led Yered Jafet
authors: LY
authors: García Montes de Oca
authors: Biochemistry and Bioenergetics Laboratory, Unidad de Biomedicina, F.E.S. Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios #1, Los Reyes Iztacala, c.p. 54090, Tlalnepantla, Estado de México, Mexico.
authors: Tecilli
authors: T
authors: Cabellos Avelar
authors: Biochemistry and Bioenergetics Laboratory, Unidad de Biomedicina, F.E.S. Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios #1, Los Reyes Iztacala, c.p. 54090, Tlalnepantla, Estado de México, Mexico.
authors: Gerardo Ignacio
authors: GI
authors: Picón Garrido
authors: Cinvestav-Departamento de Biotecnología y Bioquímica, Unidad Irapuato, Apartado Postal 629, 36503, Guanajuato, México.
authors: Alicia
authors: A
authors: Chagoya-López
authors: Cinvestav-Departamento de Biotecnología y Bioquímica, Unidad Irapuato, Apartado Postal 629, 36503, Guanajuato, México.
authors: Luis
authors: L
authors: González de la Vara
authors: Laboratory of Carcinogenesis and Toxicology, Unidad de Biomedicina, F.E.S. Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios #1, Los Reyes Iztacala, c.p. 54090, Tlalnepantla, Estado de México, Mexico.
authors: Norma Laura
authors: NL
authors: Delgado Buenrostro
authors: Laboratory of Carcinogenesis and Toxicology, Unidad de Biomedicina, F.E.S. Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios #1, Los Reyes Iztacala, c.p. 54090, Tlalnepantla, Estado de México, Mexico.
authors: Yolanda Irasema
authors: YI
authors: Chirino-López
authors: Cinvestav-Departamento de Bioquímica, Apartado Postal 14-740, 07000, México, DF, México.
authors: Carlos
authors: C
authors: Gómez-Lojero
authors: Biochemistry and Bioenergetics Laboratory, Unidad de Biomedicina, F.E.S. Iztacala, Universidad Nacional Autónoma de México, Avenida de los Barrios #1, Los Reyes Iztacala, c.p. 54090, Tlalnepantla, Estado de México, Mexico. ember@campus.iztacala.unam.mx.
authors: Emma Berta
authors: EB
authors: Gutiérrez-Cirlos
mesh_terms: D001412:Bacillus subtilis / Q000201:enzymology / Q000378:metabolism* / Q000648:ultrastructure; D001426:Bacterial Proteins / Q000378:metabolism; D018533:Biomass; D002308:Cardiolipins / Q000502:physiology*; D002462:Cell Membrane; D004579:Electron Transport / Q000502:physiology*; D009097:Multienzyme Complexes / Q000378:metabolism; D050505:Mutant Proteins; D021122:Protein Subunits; D018892:Proton-Motive Force
chemical_list: D001426:Bacterial Proteins; D002308:Cardiolipins; D009097:Multienzyme Complexes; D050505:Mutant Proteins; D021122:Protein Subunits
keywords: Aerobic respiratory chain; Bacillus subtilis; Cardiolipin; Cardiolipin-deficient mutants; Clear native electrophoresis; Supercomplexes