title: A cytochrome b561 with ferric reductase activity from the parasitic blood fluke, Schistosoma japonicum.
abstract: BACKGROUND
  Iron has an integral role in numerous cellular reactions and is required by virtually all organisms. In physiological conditions, iron is abundant in a largely insoluble ferric state. Ferric reductases are an essential component of iron uptake by cells, reducing iron to the soluble ferrous form. Cytochromes b561 (cyts-b561) are a family of ascorbate reducing transmembrane proteins found in most eukaryotic cells. The identification of the ferric reductase duodenal cytochrome b (dcytb) and recent observations that other cyts-b561 may be involved in iron metabolism have opened novel perspectives for elucidating their physiological function.
  
  
  RESULTS
  Here we have identified a new member of the cytochrome b561 (Sjcytb561) family in the pathogenic blood fluke Schistosoma japonicum that localises to the outer surface of this parasitic trematode. Heterologous expression of recombinant Sjcyt-b561 in a Saccharomyces cerevisiae mutant strain that lacks plasma membrane ferrireductase activity demonstrated that the molecule could rescue ferric reductase activity in the yeast.
  
  
  CONCLUSIONS
  This finding of a new member of the cytochrome b561 family further supports the notion that a ferric reductase function is likely for other members of this protein family. Additionally, the localisation of Sjcytb561 in the surface epithelium of these blood-dwelling schistosomes contributes further to our knowledge concerning nutrient acquisition in these parasites and may provide novel targets for therapeutic intervention.
authors.affiliation: Queensland Institute of Medical Research, Herston, Queensland, Australia.
authors.forename: Amber
authors.initials: A
authors.lastname: Glanfield
authors.forename: Donald P
authors.initials: DP
authors.lastname: McManus
authors.forename: Danielle J
authors.initials: DJ
authors.lastname: Smyth
authors.forename: Erica M
authors.initials: EM
authors.lastname: Lovas
authors.forename: Alex
authors.initials: A
authors.lastname: Loukas
authors.forename: Geoffrey N
authors.initials: GN
authors.lastname: Gobert
authors.forename: Malcolm K
authors.initials: MK
authors.lastname: Jones
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001692:Biological Transport; D002462:Cell Membrane / Q000201:enzymology / Q000235:genetics / Q000378:metabolism; D003573:Cytochrome b Group / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D038181:FMN Reductase / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015801:Helminth Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D007501:Iron / Q000378:metabolism; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D010802:Phylogeny; D021381:Protein Transport; D012549:Schistosoma japonicum / Q000737:chemistry / Q000145:classification / Q000201:enzymology* / Q000235:genetics; D012554:Schistosomiasis japonica; D016415:Sequence Alignment; D012908:Snails
chemical_list: D003573:Cytochrome b Group; D015801:Helminth Proteins; C023646:cytochrome b561; D007501:Iron; D038181:FMN Reductase; C023903:ferric citrate iron reductase