title: Membrane protein expression by Actinobacillus actinomycetemcomitans in response to iron availability.
abstract: Iron-limited growth conditions under anaerobiosis were established for Actinobacillus actinomycetemcomitans strains Y4, JP2, and 75 by use of the ferrous ion chelator 2,2'-dipyridyl. Growth inhibition was reversible with both ferrous and ferric iron sources. Sarcosyl-insoluble membrane fractions of iron-stressed anaerobic A. actinomycetemcomitans cultures revealed a similar iron-repressible protein of approximately 70 kDa in A. actinomycetemcomitans strains Y4, JP2, and 75. This 70-kDa protein was recognized by serum from localized juvenile periodontitis patients and a periodontally healthy subject. This suggested that the 70-kDa iron-repressible protein may be expressed in vivo. When A. actinomycetemcomitans was grown under aerobic conditions, the ferric iron chelator, ethylenediamine di(o-hydroxyphenylacetic acid) (EDDA) was utilized for growth limitation. EDDA inhibition was reversible in strain Y4 with ferrous and ferric iron sources. An iron-repressible protein of approximately 70 kDa was also noted in iron-stressed aerobic cultures. The 70-kDa protein may be involved in iron transport by A. actinomycetemcomitans. Preliminary experiments were performed to examine potential iron transport systems for A. actinomycetemcomitans. Production of the two most common chemical types of siderophore was not detected in A. actinomycetemcomitans culture supernatants. Iron-starved A. actinomycetemcomitans cells did not bind transferrin or lactoferrin in a dot blot assay.
authors.affiliation: Department of Oral Biology, State University of New York at Buffalo 14214-3092.
authors.forename: J L
authors.initials: JL
authors.lastname: Winston
authors.forename: C K
authors.initials: CK
authors.lastname: Chen
authors.forename: M E
authors.initials: ME
authors.lastname: Neiders
authors.forename: D W
authors.initials: DW
authors.lastname: Dyer
mesh_terms: D015082:2,2'-Dipyridyl / Q000494:pharmacology; D000332:Aerobiosis; D016976:Aggregatibacter actinomycetemcomitans / Q000378:metabolism*; D000693:Anaerobiosis; D000907:Antibodies, Bacterial / Q000096:biosynthesis; D001425:Bacterial Outer Membrane Proteins / Q000032:analysis* / Q000096:biosynthesis; D015153:Blotting, Western; D002614:Chelating Agents / Q000494:pharmacology; D004492:Edetic Acid / Q000031:analogs & derivatives / Q000494:pharmacology; D004578:Electron Spin Resonance Spectroscopy; D004591:Electrophoresis, Polyacrylamide Gel; D005290:Ferric Compounds / Q000494:pharmacology; D005296:Ferrous Compounds / Q000494:pharmacology; D006801:Humans; D015151:Immunoblotting; D017136:Ion Transport; D007501:Iron / Q000493:pharmacokinetics*; D009566:Nitrates / Q000494:pharmacology; D011956:Receptors, Cell Surface / Q000032:analysis; D011990:Receptors, Transferrin / Q000032:analysis; D017262:Siderophores / Q000032:analysis; D012967:Sodium Dodecyl Sulfate
chemical_list: D000907:Antibodies, Bacterial; D001425:Bacterial Outer Membrane Proteins; D002614:Chelating Agents; D005290:Ferric Compounds; D005296:Ferrous Compounds; D009566:Nitrates; D011956:Receptors, Cell Surface; D011990:Receptors, Transferrin; D017262:Siderophores; C038340:lactoferrin receptors; D012967:Sodium Dodecyl Sulfate; C020748:ferrous sulfate; D015082:2,2'-Dipyridyl; C026058:EDDA; D004492:Edetic Acid; D007501:Iron; C025302:ferric nitrate