ISOLATION OF A HEMIN AND HEMOGLOBIN BINDING OUTER-MEMBRANE PROTEIN OFVIBRIO-VULNIFICUS BIOTYPE-2 (SEROGROUP-E)

The eel pathogen Vibrio vulnificus biotype 2 (serogroup E) is able to use hemin (Hm) or hemoglobin (Hb) as the sole iron source for growth i n vitro and in vivo. The mechanism of heme-iron acquisition in this ba cterium requires a direct interaction through binding sites on the bac terial surface (constitutive outer membrane proteins). Using affinity chromatography techniques, a unique protein of around 36.5 kDa was iso lated from cell envelopes of E86 strain regardless of the affinity lig and used, hemoglobin or hemin. This protein was purified from both iro n-enriched and iron-restricted grown cells. These results support the hypothesis that in this pathogen Hm- and Hb-iron acquisition is mediat ed by a common protein receptor which recognizes the heme prosthetic g roup of Hb.