Abstract
Free iron availability is strongly limited in vertebrate hosts, making the iron acquisition by siderophores inappropriate. Pathogenic bacteria have developed various ways to use the host's iron from iron-containing proteins. Serratia marcescens can use the iron from hemoglobin through the secretion of a hemophore called HasA, which takes up the heme from hemoglobin and shuttles it to the receptor HasR, which in turn, releases heme into the bacterium. We report here the first crystal structure of such a hemophore, bound to a heme group at two different pH values and at a resolution of 1.9 A. The structure reveals a new original fold and suggests a hypothetical mechanism for both heme uptake and release.
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 / metabolism
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Binding Sites
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Carrier Proteins*
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Crystallization
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Crystallography, X-Ray
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Electrons
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Heme / metabolism*
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Hemoglobins / metabolism
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Hydrogen-Ion Concentration
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Iron / metabolism
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Membrane Proteins / chemistry*
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Membrane Proteins / metabolism
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Models, Molecular
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Molecular Sequence Data
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Protein Folding
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Protein Structure, Secondary
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Serratia marcescens / chemistry*
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Siderophores / chemistry*
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Siderophores / metabolism
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Sigma Factor*
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Structure-Activity Relationship
Substances
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Bacterial Proteins
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Carrier Proteins
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HasA protein, Serratia marcescens
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HasR protein, Streptomyces ambofaciens
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Hemoglobins
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Membrane Proteins
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Siderophores
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Sigma Factor
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Heme
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Iron