title: MALDI-TOF MS lipid profiles of cytochrome c oxidases: cardiolipin is not an essential component of the Paracoccus denitrificans oxidase.
abstract: Lipids of cytochrome c oxidase (COX) of Paracoccus denitrificans have been identified by MALDI-TOF MS direct analyses of isolated protein complexes, avoiding steps of lipid extraction or chromatographic separation. Two different COX preparations have been considered in this study: the enzyme core consisting of subunits I and II (COX 2-SU) and the complete complex comprising all four subunits (COX 4-SU). In addition, MALDI-TOF MS lipid profiles of bacterial COX are also compared with those of the isolated mitochondrial COX and bacterial bc1 complex. We show that the main lipids associated with bacterial COX 4-SU are phosphatidylglycerol (PG) and phosphatidylcholine (PC), and minor amounts of cardiolipin (CL). PG and PC are absent in the COX 2-SU preparation lacking subunits III and IV, whereas CL is still present. Quantitative analyses indicate that at variance from mitochondrial COX, cardiolipin is present in substoichiometric amounts in bacterial COX, at a CL:COX molar ratio of ∼1:10. We conclude that bacterial COX does not require CL for structure or its activity.
authors.affiliation: Department of Basic Medical Sciences, Neuroscience and Sensory Organs, University of Bari "A. Moro" , 70124 Bari, Italy.
authors.forename: Rita
authors.initials: R
authors.lastname: Vitale
authors.forename: Roberto
authors.initials: R
authors.lastname: Angelini
authors.forename: Simona
authors.initials: S
authors.lastname: Lobasso
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Capitanio
authors.forename: Bernd
authors.initials: B
authors.lastname: Ludwig
authors.forename: Angela
authors.initials: A
authors.lastname: Corcelli
mesh_terms: D002308:Cardiolipins / Q000032:analysis*; D003576:Electron Transport Complex IV / Q000032:analysis*; D008055:Lipids / Q000032:analysis*; D010088:Oxidoreductases / Q000032:analysis*; D010231:Paracoccus denitrificans / Q000201:enzymology*; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization / Q000379:methods*
chemical_list: D002308:Cardiolipins; D008055:Lipids; D010088:Oxidoreductases; D003576:Electron Transport Complex IV