Bacillus subtilis CtaA and CtaB function in haem A biosynthesis

Abstract

Haem A, a prosthetic group of many respiratory oxidases, is probably synthesized from haem B (protohaem IX) in a pathway in which haem O is an intermediate. Possible roles of the Bacillus subtilis ctaA and ctaB gene products in haem O and haem A synthesis were studied. Escherichia coli does not contain haem A. The ctaA gene on plasmids in E. coli resulted in haem A accumulation in membranes. The presence of ctaB together with ctaA increased the amount of haem A found in E. coli. Haem O was not detected in wild-type B. subtilis strains. A previously isolated B. subtilis ctaA deletion mutant was found to contain haem B and haem O, but not haem A. B. subtilis ctaB deletion mutants were constructed and found to lack both haem A and haem O. The results with E. coli and B. subtilis strongly suggest that the B. subtilis CtaA protein functions in haem A synthesis. It is tentatively suggested that if functions in the oxygenation/oxidation of the methyl side group of carbon 8 of haem O. B. subtilis CtaB, which is homologous to Saccharomyces cerevisiae COX10 and E. coli CyoE, also has a role in haem A synthesis and seems to be required for both cytochrome a and cytochrome o synthesis.

Listeria monocytogenesl‐forms respond to cell wall deficiency by modifying gene expression and the mode of division

“…These findings can be interpreted as a response of the L-forms to their markedly reduced surface-to-volume ratio, and agrees with the rule that enlargement of cells generally results in metabolic downregulation (Koch and Wang, 1982;Hess and Mikhailov, 1995). It also correlates with the downregulation of oxygen metabolism genes ctaA, ctaB and cydA, as a result of adaptation to a low partial oxygen pressure (Svensson et al, 1993). Downregulation of the gbu operon is likely to represent an adaptation of the cell wall deficient state to growth in environment with high water activity (aw), because the respective genes encode synthesis and uptake of compatible solutes, which is required as an adaptation to a low aw environment (Mendum and Smith, 2002).…”

Low‐spin Heme A in the Heme A Biosynthetic Protein CtaA from Bacillus Subtilis

“…B. subtilis LUB13R (trpC2 met ade ActaAB::cat), LUB29R (trpC2 met ade ActaB::cat) and RB829R (trpC2 ApycA ActaA') are better-growing isolates of the previously described strains LUBl3, LUB29 (Svensson et al, 1993) and RB829 (Mueller and Taber, 1989). The spontaneous mutations that allow these isolates to grow better than the original ones are not linked to eta (our unpublished data).…”

“…coli shuttle vectors. In B. subtilis they confer resistance to chloramphenicol and erythromycin, and have a copy number of less than 10. pCTA1303 (ctaA ctaB.536) (Svensson et al 1993) and pCTA1306 (ctaA ctaB) (this work) are derivatives of pHP13 and pHB201, respectively.…”

“…The Bacillus subtilis ctaA gene and the Saccharomyces cerevisiae COX11 gene have been identified as specifically required for heme A synthesis (Svensson et al, 1993;Tzagoloff et al, 1993). CtaA and COX1 1 (homologous to Paracoccus denitrificans CtaG) are not similar in sequence (Mueller and Taber, 1989;Tzagoloff et al, 1990).…”

“…The ctaA gene is located next to the ctuB gene at 127" on the B. subtilis chromosomal genetic map . CtaB is required for both heme 0 and heme A synthesis in B. subtilis (Svensson et al 1993).…”