IDENTIFICATION OF HEME-BINDING PROTEINS IN THE CELL-MEMBRANES OF VIBRIO-ANGUILLARUM

Two strains of Vibrio anguillarum belonging to O1 and O2 serotypes wer e examined for their ability to bind hemin and hemoglobin. Whole cells as well as membrane extracts from both strains could clearly bind hem in and hemoglobin constitutively. Hemoglobin binding was completely in hibited by a 100-fold excess of unlabelled hemoglobin and also by hemi n, suggesting the existence of specific receptors for heme groups in t he cell membranes. Several hemin-binding and hemoglobin-binding bands with similar molecular sizes were detected in polyacrylamide gels as w ell as in Western blots. Only two of these protein bands in both strai ns were iron-regulated while the others were independent of the cell i ron status. We conclude that both serotypes of V. anguillarum possess heme-binding abilities by means of membrane proteins.