title: Utilization of haem from the haptoglobin-haemoglobin complex by Bacteroides fragilis.
abstract: Possession of specialized iron acquisition systems is a prerequisite for the survival of pathogenic bacteria in their host. The purpose of this study was to determine whether Bacteroides fragilis, a clinically important Gram-negative anaerobic bacterium, possesses a specific haem-uptake system. Growth studies indicated that this microorganism can utilize haem from either haemoglobin or haptoglobin-haemoglobin as its sole source of iron. Iron-repressible haem-binding protein complexes (HBP complexes), involved in the uptake of haem from haptoglobin-haemoglobin were detected by means of lithium dodecyl sulfate polyacrylamide gel electrophoresis (LDS-PAGE). Four polypeptides of approximately 60, 58, 49 and 35 kDa, which are part of these HBP complexes, were identified as haem-binding proteins. A 44 kDa iron-repressible outer-membrane protein is needed for a functional HBP complex, but the exact role of this protein in the uptake of haem is still unknown.
authors.affiliation: Department of Molecular Microbiology, Faculty of Biology, Vrije Universiteit, Amsterdam, The Netherlands.
authors.forename: B R
authors.initials: BR
authors.lastname: Otto
authors.forename: M
authors.initials: M
authors.lastname: Sparrius
authors.forename: D J
authors.initials: DJ
authors.lastname: Wors
authors.forename: F K
authors.initials: FK
authors.lastname: de Graaf
authors.forename: D M
authors.initials: DM
authors.lastname: MacLaren
mesh_terms: D001441:Bacteroides fragilis / Q000378:metabolism*; D002352:Carrier Proteins / Q000378:metabolism; D002846:Chromatography, Affinity; D003224:Congo Red; D004591:Electrophoresis, Polyacrylamide Gel; D006242:Haptoglobins / Q000378:metabolism*; D006418:Heme / Q000378:metabolism*; D000081062:Heme-Binding Proteins; D006420:Hemeproteins / Q000378:metabolism; D006454:Hemoglobins / Q000378:metabolism*; D008970:Molecular Weight; D010455:Peptides / Q000378:metabolism
chemical_list: D002352:Carrier Proteins; D006242:Haptoglobins; D000081062:Heme-Binding Proteins; D006420:Hemeproteins; D006454:Hemoglobins; D010455:Peptides; C035492:haptoglobin-hemoglobin complex; D003224:Congo Red; D006418:Heme