Abstract
Many pathogenic bacteria can use heme compounds as a source of iron. Pathogenic Escherichia coli strains are capable of using hemoglobin as an iron source. However, the mechanism of heme acquisition from hemoglobin is not understood for this microorganism. We present the first molecular characterization of a hemoglobin protease (Hbp) from a human pathogenic E. coli strain. The enzyme also appeared to be a heme-binding protein. Affinity purification of this bifunctional protein enabled us to identify the extracellular gene product, and to clone and analyze its gene. A purification procedure developed for Hbp allowed us to perform functional studies. The protein interacted with hemoglobin, degraded it and subsequently bound the released heme. These results suggest that the protein is involved in heme acquisition by this human pathogen. Hbp belongs to the so-called IgA1 protease-like proteins, as indicated by the kinetics of its membrane transfer and DNA sequence similarity. The gene of this protein appears to be located on the large pColV-K30 episome, that only has been isolated from human and animal pathogens. All these characteristics indicate that Hbp may be an important virulence factor that may play a significant role in the pathogenesis of E. coli infections.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Bacterial Proteins / chemistry
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Bacterial Proteins / genetics
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Bacterial Proteins / isolation & purification
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Bacterial Proteins / metabolism
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Carrier Proteins / chemistry
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Carrier Proteins / metabolism
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Culture Media / chemistry
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Deoxyribonuclease EcoRI / genetics
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Deoxyribonuclease HindIII / genetics
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Endopeptidases / chemistry*
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Endopeptidases / genetics
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Endopeptidases / isolation & purification
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Endopeptidases / metabolism
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Enzyme Activation
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Escherichia coli / enzymology*
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Escherichia coli / genetics
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Escherichia coli / growth & development
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Escherichia coli / pathogenicity*
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Extracellular Space / enzymology
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Extracellular Space / metabolism
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Heme-Binding Proteins
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Hemeproteins / chemistry
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Hemeproteins / metabolism
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Hemoglobins / metabolism*
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Humans
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Molecular Sequence Data
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Peptide Fragments / genetics
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Peptide Fragments / isolation & purification
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Plasmids / genetics
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Sequence Analysis, DNA
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Serine Endopeptidases / chemistry*
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Serine Endopeptidases / genetics
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Serine Endopeptidases / isolation & purification
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Serine Endopeptidases / metabolism
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Subcellular Fractions / enzymology
Substances
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Bacterial Proteins
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Carrier Proteins
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Culture Media
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Heme-Binding Proteins
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Hemeproteins
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Hemoglobins
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Peptide Fragments
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Deoxyribonuclease EcoRI
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Deoxyribonuclease HindIII
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Endopeptidases
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Serine Endopeptidases
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hemoglobin protease Hbp