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. Author manuscript; available in PMC: 2010 Apr 1.
Published in final edited form as: Mol Microbiol. 2009 Feb 15;72(1):109–123. doi: 10.1111/j.1365-2958.2009.06627.x

Figure 8.

Figure 8

Schematic representation of the small c-type cytochrome pathway regulating virulence gene expression in B. anthracis. Intracellularly synthesized heme, through a pathway that requires the Hem proteins including HemL, is transported across the membrane by the ResBC proteins (Ahuja et al., 2007) and is covalently attached to CccA and CccB with the involvement of ResA (Le Brun et al., 2000). Either CccA or CccB can then act to indirectly repress atxA transcription at the P1 promoter and their function is redundant. The BAS3568 protein, which is required for full cytochrome oxidase activity, is also involved in repression of atxA transcription in early exponential phase by an unknown mechanism (indicated by the broken arrow) likely to act on the cytochrome c maturation pathway. The BAS3568 protein does not share amino acid similarity with the Res proteins. The sidedness of the membrane is indicated by “in” and “out”.