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Appl. Environ. Microbiol., Aug 1996, 2806-2810, Vol 62, No. 8
B Fouz, R Mazoy, ML Lemos, MJ del Olmo and C Amaro
The eel pathogen Vibrio vulnificus biotype 2 is able to use hemoglobin (Hb)
and hemin (Hm) to reverse iron limitation. In this stud, the adjuvant
effect of both compounds on eel pathogenicity has been evaluated and
confirmed. Further, we have studied the heme-iron acquisition mechanism
displayed by this bacterium. Whole cells were capable of binding Hb and Hm,
independently of (i) iron levels in growth medium and (ii) the presence of
polysaccharide capsules on bacterial surface. The Hb- and Hm-binding
capacity was retained by the outer membrane protein (OMP) fraction and was
abolished after proteolytic digestion of OMP samples. Western blotting
(immunoblotting) of denatured OMPs revealed that two major protein bands of
36 and 32 kDa were involved in both Hm and Hb binding. The expression of
these proteins was not affected by iron levels. In addition, V. vulnificus
biotype 2 produced extracellular proteases, not regulated by iron, that
were active against native Hb. In conclusion, the overall data suggest that
the eel pathogen V. vulnificus biotype 2 can obtain iron by means of a
mechanism which involves a direct interaction between the heme moiety and
constitutive OMPs.
Copyright © 1996, American Society for Microbiology
Utilization of hemin and hemoglobin by Vibrio vulnificus biotype 2
Departamento de Microbiologia, Facultad de Biologia, Universidad de Valencia, Spain.
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