title: Heme O synthase and heme A synthase from Bacillus subtilis and Rhodobacter sphaeroides interact in Escherichia coli.
abstract: 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.
authors.affiliation: Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, USA.
authors.forename: Brienne M
authors.initials: BM
authors.lastname: Brown
authors.forename: Zhihong
authors.initials: Z
authors.lastname: Wang
authors.forename: Kenneth R
authors.initials: KR
authors.lastname: Brown
authors.forename: Julia A
authors.initials: JA
authors.lastname: Cricco
authors.forename: Eric L
authors.initials: EL
authors.lastname: Hegg
mesh_terms: D019883:Alkyl and Aryl Transferases / Q000302:isolation & purification / Q000378:metabolism*; D001412:Bacillus subtilis / Q000201:enzymology*; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D003001:Cloning, Molecular; D003573:Cytochrome b Group / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D003576:Electron Transport Complex IV / Q000378:metabolism; D004926:Escherichia coli / Q000201:enzymology*; D005294:Ferrochelatase / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism*; D006418:Heme / Q000031:analogs & derivatives* / Q000378:metabolism; D008565:Membrane Proteins / Q000235:genetics / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D016366:Open Reading Frames; D017368:Protein Prenylation; D012242:Rhodobacter sphaeroides / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; C107633:COX15 protein, S cerevisiae; C090098:CtaA protein, bacteria; D003573:Cytochrome b Group; D008565:Membrane Proteins; D029701:Saccharomyces cerevisiae Proteins; C069808:heme O; C027728:heme a; D006418:Heme; D003576:Electron Transport Complex IV; D019883:Alkyl and Aryl Transferases; C086105:COX10 protein, S cerevisiae; C078356:CyoE protein, Bacteria; D005294:Ferrochelatase