Publications

• Isolation of a human cDNA for heme A:farnesyltransferase by functional complementation of a yeast cox10 mutant.

  Glerum M.D., Tzagoloff A.

  We have cloned the human homolog of the Saccharomyces cerevisiae COX10 gene by functional complementation of a yeast cox10 null mutant. The 2.8-kb cDNA encoding the human heme A:farnesyltransferase codes for a 443-aa protein with high homology to the yeast and bacterial farnesylases. The human COX ... >> More

  We have cloned the human homolog of the Saccharomyces cerevisiae COX10 gene by functional complementation of a yeast cox10 null mutant. The 2.8-kb cDNA encoding the human heme A:farnesyltransferase codes for a 443-aa protein with high homology to the yeast and bacterial farnesylases. The human COX10 homolog, however, does not complement the mutation as efficiently as the yeast COX10 protein, likely due to the heterologous environment. PCR amplification and Southern analysis confirm the existence of a large mRNA for the human protein, with an unusually long 3' untranslated region. This clone can now be used to screen patients with inherited deficiencies in cytochrome oxidase in which the mutations remain unidentified and are likely to reside in a protein influencing the assembly of the enzyme. << Less

  Proc. Natl. Acad. Sci. U.S.A. 91:8452-8456(1994) [PubMed] [EuropePMC]

• Heme O biosynthesis in Escherichia coli: the cyoE gene in the cytochrome bo operon encodes a protoheme IX farnesyltransferase.

  Saiki K., Mogi T., Anraku Y.

  The cytochrome bo complex of Escherichia coli is encoded by the cyoABCDE operon and functions as a redox-coupled proton pump. In this study, we have constructed eight cyoE deletion mutants and found that all the mutants were nonfunctional. Spectroscopic and heme analyses of the mutant oxidases rev ... >> More

  The cytochrome bo complex of Escherichia coli is encoded by the cyoABCDE operon and functions as a redox-coupled proton pump. In this study, we have constructed eight cyoE deletion mutants and found that all the mutants were nonfunctional. Spectroscopic and heme analyses of the mutant oxidases revealed that the mutations specifically substituted protoheme IX for heme O present in the high-spin heme binding site. We found also that the overexpression of the cyoE gene in a cyo operon deletion strain resulted in a conversion of protoheme IX to heme O. Since the CyoE protein contains the putative allylic polyprenyldiphosphate binding domain, we concluded that the cyoE gene encodes a novel enzyme, protoheme IX farnesyltransferase, essential for heme O biosynthesis. << Less

  Biochem. Biophys. Res. Commun. 189:1491-1497(1992) [PubMed] [EuropePMC]

• Over-expression and characterization of Bacillus subtilis heme O synthase.

  Mogi T.

  Biosynthesis of heme A from heme B is catalysed by two enzymes, heme O and heme A synthases, in the membrane. Heme O synthase in Bacillus subtilis (CtaB) has eight transmembrane helices and catalyses the transfer of a farnesyl group from farnesyl diphosphate to the 2-vinyl group on pyrrole ring A ... >> More

  Biosynthesis of heme A from heme B is catalysed by two enzymes, heme O and heme A synthases, in the membrane. Heme O synthase in Bacillus subtilis (CtaB) has eight transmembrane helices and catalyses the transfer of a farnesyl group from farnesyl diphosphate to the 2-vinyl group on pyrrole ring A of ferrous heme B. In this study, we constructed the overproduction system for the B. subtilis CtaB in Escherichia coli. We isolated His(7)-CtaB by affinity chromatography and demonstrated the presence of the heme-binding site in heme O synthase. His(7)-CtaB binds substoichiometric amounts of heme B and O, substrate and unreleased product, respectively. Mutagenesis studies suggest that strictly conserved His199 present at the extra-cellular side of helix 5 would serve as the heme-binding site. We are hoping that the overproducing system for heme O synthase would help understanding of detailed mechanism on heme O biosynthesis and X-ray crystallographic studies. << Less

  J. Biochem. 145:669-675(2009) [PubMed] [EuropePMC]

• Bacillus subtilis CtaA and CtaB function in haem A biosynthesis.

  Svensson B., Lubben M., Hederstedt L.

  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 co ... >> More

  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. << Less

  Mol Microbiol 10:193-201(1993) [PubMed] [EuropePMC]

• Heme O synthase and heme A synthase from Bacillus subtilis and Rhodobacter sphaeroides interact in Escherichia coli.

  Brown B.M., Wang Z., Brown K.R., Cricco J.A., Hegg E.L.

  Cytochrome c oxidase requires multiple heme and copper cofactors to catalyze the reduction of molecular oxygen to water. Although significant progress has been made in understanding the transport and incorporation of the copper ions, considerably less is known about the trafficking and insertion o ... >> More

  Cytochrome c oxidase requires multiple heme and copper cofactors to catalyze the reduction of molecular oxygen to water. Although significant progress has been made in understanding the transport and incorporation of the copper ions, considerably less is known about the trafficking and insertion of the heme cofactors. Heme O synthase (HOS) and heme A synthase (HAS) from Rhodobacter sphaeroides (Cox10 and Cox15, respectively) and Bacillus subtilis (CtaB and CtaA, respectively) have been cloned and expressed in Escherichia coli. Our results demonstrate that HOS copurifies with HAS and that HAS copurifies with HOS, indicating that HOS and HAS interact and may form a physiologically relevant complex in vivo. Consistent with this hypothesis, the presence of HAS alters the total level of farnesylated hemes, providing further evidence that HOS and HAS interact. Our current working model is that HOS and HAS form a complex and that heme O is transferred directly from HOS to HAS. Because of the strong sequence similarity and evolutionary relationship between R. sphaeroides and mitochondria, our data suggest that this complex may form in eukaryotes as well. << Less

  Biochemistry 43:13541-13548(2004) [PubMed] [EuropePMC]