Identification of a genetic locus of Haemophilus influenzae type b necessary for the binding and utilization of heme bound to human hemopexin

Mark S. Hanson, Sharon E. Pelzel, J. O. Latimer, Ursula Muller-Eberhard, Eric J. Hansen

Research output: Contribution to journalArticlepeer-review

58 Scopus citations

Abstract

The mechanism(s) used by Haemophilus influenzae to acquire the essential nutrient heme from its human host has not been elucidated. The heme carried by the high-affinity serum protein hemopexin is one potential source of this micronutrient in vivo. A colony-blot assay revealed that heme-human hemopexin-binding activity was shared among most capsular serotype b strains of H. influenzae but was uncommon among other strains. We have identified a recombinant clone binding heme-human hemopexin from a H. influenzae type b (Hib) genomic library expressed in Escherichia coli. Both the Hib strain and the heme-hemopexin-binding clone expressed a polypeptide of ≃100 kDa that bound radiolabeled heme-hemopexin. Oligonucleotide linker insertion mutagenesis of the plasmid DNA from this recombinant clone was used to confirm that expression of the 100-kDa protein correlated with the heme- hemopexin-binding activity. Exchange of one of these mutant alleles into the Hib chromosome eliminated expression of both the 100-kDa protein and the heme-hemopexin-binding activity. Furthermore, this Hib mutant was unable to utilize heme-human hemopexin as a heme source.

Original languageEnglish (US)
Pages (from-to)1973-1977
Number of pages5
JournalProceedings of the National Academy of Sciences of the United States of America
Volume89
Issue number5
DOIs
StatePublished - 1992

Keywords

  • bacterial pathogenesis
  • heme acquisition

ASJC Scopus subject areas

  • General

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