Low-spin heme A in the heme A biosynthetic protein CtaA from Bacillus subtilis.

Publisher: Blackwell Science Ltd. on behalf of the Federation of European Biochemical Societies Country of Publication: England NLM ID: 0107600 Publication Model: Print Cited Medium: Print ISSN: 0014-2956 (Print) Linking ISSN: 00142956 NLM ISO Abbreviation: Eur J Biochem Subsets: MEDLINE

Publication: -2004: Oxford, UK : Blackwell Science Ltd. on behalf of the Federation of European Biochemical Societies
Original Publication: Berlin, New York, Springer.

Bacterial Proteins*; Bacillus subtilis/*enzymology ; Cytochrome b Group/*chemistry ; Cytochrome b Group/*genetics ; Heme/*chemistry ; Membrane Proteins/*chemistry ; Membrane Proteins/*genetics; Base Sequence ; Cytochrome a Group/biosynthesis ; Cytochrome a Group/chemistry ; Cytochrome a Group/genetics ; Cytochrome b Group/biosynthesis ; Electron Spin Resonance Spectroscopy ; Heme/biosynthesis ; Membrane Proteins/biosynthesis ; Molecular Sequence Data ; Mutation ; Plasmids/chemistry ; Plasmids/genetics ; Recombinant Proteins/biosynthesis ; Recombinant Proteins/chemistry ; Recombinant Proteins/genetics ; Spectrum Analysis/methods ; Temperature

Synthesis of heme A from heme B (protoheme IX) most likely occurs in two steps with heme O as an intermediate. Bacillus subtilis CtaB, an integral membrane protein, functions in farnesylation of heme B to form heme O. CtaA, also a membrane protein, is required for heme A synthesis from heme O and appears to be a monooxygenase and/or a dehydrogenase. Wild-type ctaA and ctaB expressed together from plasmids in B. subtilis resulted in CtaA containing equimolar amounts of low-spin heme B and heme A; this form of CtaA was named cyt ba-CTA. A mutant ctaB gene was identified and characterised. It encodes a truncated CtaB polypeptide. Wild-type ctaA and the mutant ctaB gene on plasmids resulted in CtaA containing mainly low-spin heme B; this variant was named cyt b-CTA. The heme B component in cyt ba-CTA and cyt b-CTA showed identical properties; a mid-point redox potential of +85 mV, an EPR g(max) signal at 3.7, and a split alpha-band light absorption peak. The heme A component in cyt ba-CTA showed a mid-point potential of +242 mV, an EPR g(max) signal at 3.5, and the alpha-band light absorption peak at 585 nm. It is suggested that the CtaA protein contains two heme binding sites, one for heme B and one for substrate heme. The heme B would play a role in electron transfer, i.e. function as a cytochrome, in the monooxygenase and/or dehydrogenase reaction catalysed by CtaA whereas heme O/heme A would be substrate/product.

0 (Bacterial Proteins)
0 (CtaA protein, bacteria)
0 (Cytochrome a Group)
0 (Cytochrome b Group)
0 (Membrane Proteins)
0 (Recombinant Proteins)
42VZT0U6YR (Heme)

Date Created: 19960515 Date Completed: 19960802 Latest Revision: 20190620

20231215

10.1111/j.1432-1033.1996.0287q.x

8665949