Haem O and a putative cytochrome bo in a mutant of Bacillus cereus impaired in the synthesis of haem A |
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Authors: | I P Del Arenal M L Contreras B B Svlateorova P Rangel F Lledías J R Dávila J E Escamilla |
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Institution: | (1) Departamento de Bioquímica, Facultad de Medicina, Universidad Nacional Autónoma de México, Apartado postal 70–159, 04510 México, D.F, México, XX;(2) Escuela de Biología, Universidad Autónoma de Puebla, Puebla, Mexico, MX;(3) Instituto de Fisiología Celular, Universidad Nacional Autónoma de México, Apartado postal 70–242, 04510 México, D.F., México Tel. +525 622-5627/5628; Fax +525 622-5630 e-mail: eescami@.ifisiol.unam.mx, XX |
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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 caa
3
-OII and aa
3
-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 caa
3
-COI and aa
3
-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.
Received: 21 June 1996 / Accepted: 9 October 1996 |
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Keywords: | Bacillus cereus Haem O Cytochrome bo Cytochrome aa3 cytochrome caa3 Bacillus sporulation |
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