CHARACTERIZATION AND ENVIRONMENTAL-REGULATION OF OUTER-MEMBRANE PROTEINS IN XENORHABDUS-NEMATOPHILUS

We have examined the production of the outer membrane proteins of the primary and secondary forms of Xenorhabdus nematophilus during exponen tial- and stationary-phase grow,vth at different temperatures. The mos t highly expressed outer membrane protein of X. nematophilus was OpnP. The amino acid composition of OpnP was very similar to those of the p orin proteins OmpF and OmpC of Escherichia coli. N-terminal amino acid sequence analysis revealed that residues 1 to 27 of the mature OpnP s hared 70 and 60% sequence identities with OmpC and OmpF, respectively. These results suggest that OpnP is a major porin protein in X. nemoto philus. Three additional proteins, OpnA, OpnB, and OpnS, were induced during stationary-phase growth. OpnB was-present at a high level in st ationary-phase cells grown at 19 to 30 degrees C and was repressed in cells grown at 34 degrees C. OpnA was optimally produced at 30 degrees C and was not present in cells grown at lower and higher temperatures . The production of OpnS was not dependent on growth temperature. In c ontrast, another outer membrane protein, OpnT, was strongly induced as the growth temperature was elevated from 19 to 34 degrees C. In addit ion, we show that the stationary-phase proteins OpnA and OpnB were not produced in secondary-form cells.