title: Haem O and a putative cytochrome bo in a mutant of Bacillus cereus impaired in the synthesis of haem A.
abstract: In a spontaneous mutant (PYM1) of Bacillus cereus impaired in the synthesis of haem A, no haem-A-containing cytochromes were detected spectroscopically. The haem A deficiency was compensated by high levels of haem O and a CO-reactive cytochrome o in membranes; no other oxidases were detected. In contrast, the wild-type strain had considerable amounts of haem A and negligible levels of haem O. The mutant PYM1 exhibited normal colony morphology, growth, and sporulation in nonfermentable media, whereas on fermentable media, the mutant overproduced acid, which led to poor growth and inhibition of sporulation. External control of the pH of the medium in fermentable media allowed close-to-normal growth and massive sporulation of the mutant. The presence of membrane-bound cytochrome caa3-OII and aa3-II subunits in strain PYM1 was confirmed by Western blots and haem C staining (COII subunit). Western blotting also revealed that in contrast to the wild-type - strain PYM1 contained the membrane-bound subunits caa3-COI and aa3-I, but in low amounts. The effect of several respiratory inhibitors on the respiratory system of strain PYM1 suggested that the terminal oxidase is highly resistant to KCN and CO and that a c-type cytochrome might be involved in the electron transfer sequence to the putative cytochrome bo.
authors.affiliation: Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado postal 70-159, 04510 México, D.F, México.
authors.forename: I P
authors.initials: IP
authors.lastname: Del Arenal
authors.forename: M L
authors.initials: ML
authors.lastname: Contreras
authors.forename: B B
authors.initials: BB
authors.lastname: Svlateorova
authors.forename: P
authors.initials: P
authors.lastname: Rangel
authors.forename: F
authors.initials: F
authors.lastname: Lledías
authors.forename: J R
authors.initials: JR
authors.lastname: Dávila
authors.forename: J E
authors.initials: JE
authors.lastname: Escamilla
mesh_terms: D001409:Bacillus cereus / Q000378:metabolism*; D003573:Cytochrome b Group; D003574:Cytochrome c Group / Q000378:metabolism; D003580:Cytochromes / Q000032:analysis*; D029968:Escherichia coli Proteins; D006418:Heme / Q000032:analysis* / Q000096:biosynthesis; D008970:Molecular Weight; D009097:Multienzyme Complexes / Q000378:metabolism; D009154:Mutation; D009247:NADH, NADPH Oxidoreductases / Q000378:metabolism; D010084:Oxidation-Reduction; D011190:Potassium Cyanide / Q000494:pharmacology; D013171:Spores, Bacterial / Q000502:physiology
chemical_list: D003573:Cytochrome b Group; D003574:Cytochrome c Group; D003580:Cytochromes; D029968:Escherichia coli Proteins; D009097:Multienzyme Complexes; C069808:heme O; D006418:Heme; C017168:cytochrome bo, E coli; C023107:NADH oxidase; D009247:NADH, NADPH Oxidoreductases; D011190:Potassium Cyanide