Skip to Main content Skip to Navigation
Journal articles

Purification and characterization of an extracellular heme-binding protein, HasA, involved in heme iron acquisition.

Abstract : Many bacterial hemoproteins involved in heme acquisition have been isolated recently, comprising outer membrane receptors and extracellular heme-binding protein. The mechanisms by which these proteins extract heme have not been described up to now. One such protein, HasA, which can bind free heme as well as capture it from hemoglobin, is secreted by the Gram-negative bacteria Serratia marcescens under iron deficiency conditions. The fact that HasA does not present sequence similarities with other known hemoproteins suggests that it possesses a new type of heme binding site. This work describes the main physicochemical properties of HasA, essential for understanding its function. HasA is a monomer of 19 kDa that binds one b heme per molecule with high affinity. The electron paramagnetic resonance spectra indicate that the heme iron is in a low-spin ferric state and that the two iron axial ligands are His and His-. The low oxidation-reduction potential value (-550 mV vs standard hydrogen electrode) of the heme bound to HasA suggests that heme could be exposed to the solvent. According to circular dichroism data, the binding of heme does not seem to modify the conformation of HasA.
Document type :
Journal articles
Complete list of metadatas

https://hal-pasteur.archives-ouvertes.fr/pasteur-00368062
Contributor : Cécile Roux <>
Submitted on : Friday, March 13, 2009 - 2:51:02 PM
Last modification on : Tuesday, July 21, 2020 - 3:58:40 AM

Links full text

Identifiers

Collections

Citation

Nadia Izadi, Yann Henry, Jean Haladjian, Michel E. Goldberg, Cécile Wandersman, et al.. Purification and characterization of an extracellular heme-binding protein, HasA, involved in heme iron acquisition.. Biochemistry, American Chemical Society, 1997, 36 (23), pp.7050-7. ⟨10.1021/bi962577s⟩. ⟨pasteur-00368062⟩

Share

Metrics

Record views

276