title: Elemental iron does repress transferrin, haemopexin and haemoglobin receptor expression in Haemophilus influenzae.
abstract: The iron repressible nature of Haemophilus influenzae transferrin binding proteins suggests a regulatory role for elemental iron in their expression. The existence of a Haemophilus ferric uptake repressor (Fur) binding motif identified in the promoter region of both tbpA and tbpB further supports this hypothesis. However, a recent study using brain heart infusion growth medium suggested that transferrin binding protein synthesis in H. influenzae was haem-rather than iron-regulated. The present study re-investigates this observation and using a chemically defined medium, we demonstrate that elemental iron haem or protoporphyrin IX can each regulate Haemophilus influenzae transferrin, haemopexin and haemoglobin receptor expression.
authors.affiliation: Department of Pharmaceutical Sciences, University of Nottingham, University Park, UK.
authors.forename: A A
authors.initials: AA
authors.lastname: Hasan
authors.forename: J
authors.initials: J
authors.lastname: Holland
authors.forename: A
authors.initials: A
authors.lastname: Smith
authors.forename: P
authors.initials: P
authors.lastname: Williams
mesh_terms: D002352:Carrier Proteins / Q000096:biosynthesis / Q000378:metabolism; D002712:Chlorides; D003470:Culture Media; D015536:Down-Regulation / Q000187:drug effects*; D005290:Ferric Compounds / Q000494:pharmacology*; D006193:Haemophilus influenzae / Q000254:growth & development / Q000378:metabolism*; D006418:Heme / Q000494:pharmacology; D006454:Hemoglobins / Q000378:metabolism / Q000494:pharmacology; D006466:Hemopexin / Q000378:metabolism; D033862:Iron-Binding Proteins; D011524:Protoporphyrins / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018000:Receptors, Peptide / Q000378:metabolism; D011990:Receptors, Transferrin / Q000378:metabolism; D014168:Transferrin / Q000378:metabolism; D033863:Transferrin-Binding Proteins
chemical_list: D002352:Carrier Proteins; D002712:Chlorides; D003470:Culture Media; D005290:Ferric Compounds; D006454:Hemoglobins; D033862:Iron-Binding Proteins; D011524:Protoporphyrins; D011956:Receptors, Cell Surface; D018000:Receptors, Peptide; D011990:Receptors, Transferrin; D014168:Transferrin; D033863:Transferrin-Binding Proteins; C047453:hemopexin receptor; D006418:Heme; D006466:Hemopexin; C028025:protoporphyrin IX; C024555:ferric chloride