title: Intra- and inter-complex cross-linking of subunits in the quinol oxidase super-complex from thermophilic Bacillus PS3.
abstract: Gram-positive thermophilic Bacilli contain quinol-cytochrome c reductase and cytochrome c oxidase as two major respiratory complexes of the electron transfer chain, and these enzymes can be extracted with mild detergents as an associated quinol oxidase super-complex. The reductase is composed of three subunits; cytochrome b6, cytochrome c1, and FeS protein, whereas cytochrome c oxidase consists of four subunits numbered 1 through 4. In order to clarify the interactions between the subunits, the super-complex isolated from Bacillus PS3 was cross-linked with three bifunctional cross-linkers; disuccinimidyl tartrate, 3,3'-dithiobis(succinimidylpropionate), and ethylene glycolbis(sulfosuccinimidylsuccinate). The most prominent cross-linking was observed for the combination of subunit 1 plus 2 in cytochrome c oxidase, and for that of cytochrome b6 plus cytochrome c1 in the reductase. In addition to these intra-complex cross-linkings, inter-complex linking was observed for the combination of cytochrome b6 plus subunit 1 with ethylene glycolbis(sulfosuccinimidylsuccinate), and for the combinations of cytochrome b6 plus subunit 1 and cytochrome b6 plus subunit 2 with 3,3'-dithiobis(succinimidylpropionate). Incubation in the presence of Triton X-100, which was confirmed to cleave the two enzyme complexes, selectively reduced the inter-complex cross-linking, suggesting that the chemical cross-linking reflect the spatial arrangement of subunits in the super-complex.
authors.affiliation: Department of Biochemical Engineering and Science, Kyushu Institute of Technology, Fukuoka.
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
authors.forename: M
authors.initials: M
authors.lastname: Inoue
authors.forename: J
authors.initials: J
authors.lastname: Sakamoto
authors.forename: N
authors.initials: N
authors.lastname: Sone
mesh_terms: D001407:Bacillus / Q000201:enzymology*; D014450:Electron Transport Complex III / Q000737:chemistry*; D003576:Electron Transport Complex IV / Q000737:chemistry*; D015180:Electrophoresis, Gel, Two-Dimensional; D009097:Multienzyme Complexes / Q000737:chemistry*; D017830:Octoxynol; D011487:Protein Conformation
chemical_list: D009097:Multienzyme Complexes; D017830:Octoxynol; D003576:Electron Transport Complex IV; D014450:Electron Transport Complex III