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Mol Microbiol. 1998 Jun;28(6):1223-34.

Isolation and characterization of an extracellular haem-binding protein from Pseudomonas aeruginosa that shares function and sequence similarities with the Serratia marcescens HasA haemophore.

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Unité de Physiologie Cellulaire Institut Pasteur (CNRS URA 1300), Paris, France.


The major mechanism by which bacteria acquire free or haemoglobin-bound haem involves direct binding to specific outer membrane receptors. Serratia marcescens also secretes a haem-binding protein, HasA, which functions as a haemophore that catches haem and shuttles it to a cell surface specific outer membrane receptor, HasR. We report the isolation and characterization of hasAp, a gene from Pseudomonas aeruginosa. HasAp is an iron-regulated extracellular haem-binding protein that shares about 50% identity with HasA. HasAp is required for P. aeruginosa utilization of haemoglobin iron. It can replace HasA for HasR-dependent haemoblobin acquisition in a system reconstituted in Escherichia coli. HasAp, like HasA, lacks a signal peptide and is secreted by an ABC transporter. These findings show that haemophore-dependent haem acquisition is not unique to S. marcescens.

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