THE SURFACE EXCLUSION SYSTEM OF RP1 - INVESTIGATION OF THE ROLES OF TRBJ AND TRBK IN THE SURFACE EXCLUSION, TRANSFER, AND SLOW-GROWTH PHENOTYPES

The contiguous trbJ and trbK genes of RP1 were cloned individually to study their effects. Surface exclusion was conferred only by trbK and only when gene dosage was high or when trbJ was also present in cis or in trans. This suggests that in the low-copy-number RP1, surface excl usion is due to a two-gene interaction in which trbK is the dominant p artner. Among surface exclusion genes, trbJ is novel in yielding a per iplasmic product that is also essential for conjugal transfer. This ce llular location and the disturbed membrane function that accompanies T rbJ-processing probably accounts for the retarded growth caused by trb J(+) clones in Pseudomonas aeruginosa strain PAO. (C) 1994 Academic Pr ess, Inc.