Ip. Delarenal et al., HEME-O AND HEME-A PUTATIVE CYTOCHROME BO IN A MUTANT OF BACILLUS-CEREUS IMPAIRED IN THE SYNTHESIS OF HEME-A, Archives of microbiology, 167(1), 1997, pp. 24-31
In a spontaneous mutant (PYM1) of Bacillus cel eus impaired in the syn
thesis of haem Al no haem-A-containing cytochromes were detected spect
roscopically. The haem A deficiency was compensated by high levels of
haem O and a GO-reactive cytochrome o in membranes; no other oxidases
were detected. In contrast, the wild-type strain had considerable amou
nts of haem A and negligible levels of haem O. The mutant PYM1 exhibit
ed normal colony morphology. growth, and sporulation in nonfermentable
media, whereas on fermentable media, the mutant overproduced acid, wh
ich 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 (COLI subunit). Western
blotting also revealed that in contrast to the wild-type - strain PYM
1 contained the membrane-bound subunits caa(3)-COI and aa(3)-I, but in
low amounts. The effect of several respiratory inhibitors on the resp
iratory system of strain PYM1 suggested that the terminal oxidase is h
ighly resistant to KCN and CO and that a c-type cytochrome might be in
volved in the electron transfer sequence to the putative cytochrome bo
.