Cardiolipin deficiency causes a dissociation of the b ₆ c:caa ₃ megacomplex in B. subtilis membranes

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• 作者：Led Yered Jafet García Montes de Oca…
• 关键词：Bacillus subtilis ; Aerobic respiratory chain ; Supercomplexes ; Cardiolipin ; Cardiolipin ; deficient mutants ; Clear native electrophoresis
• 刊名：Journal of Bioenergetics and Biomembranes
• 出版年：2016
• 出版时间：August 2016
• 年：2016
• 卷：48
• 期：4
• 页码：451-467
• 全文大小：2,549 KB
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Chemistry
  Bioorganic Chemistry
  Biochemistry
  Animal Anatomy, Morphology and Histology
  Animal Biochemistry
  Organic Chemistry
  
• 出版者：Springer New York
• ISSN：1573-6881
• 卷排序：48

文摘

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 b₆c complex that has a b₆ 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 b₆f complex. Cytochrome c oxygen reductase (caa₃) contains a c-type cytochrome on subunit I. We previously showed that the b₆c and the caa₃ complexes form a supercomplex. Both the b₆c and the caa₃ together with the quinol oxygen reductase aa₃ 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 b₆c: caa₃ 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 b₆c:caa₃ 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 b₆c:caa₃ supercomplex in B. subtilis.