PORINS OF BRUCELLA SPECIES

The outer membrane of Brucella spp. contains 2 major proteins, denoted as group 2 and group 3 proteins. Proteoliposomes were reconstituted from the purified proteins and egg phosphatidylcholine and showed that group 2 proteins, but not a group 3 protein, had the porin activity. The influx rates of sugars of various sizes into the proteoliposomes indicated that the porin channels and apparent diameters in a range comparable to that of Escherichia coli OmpF porin and that the channels were predominantly open. Among different Brucella spp., there were small but detectable differences in the channel diameter; it was possible to explain the differential sensitivity of several Brucella species to diagnostic dyes on the basis of these observed differences.