Expression of degradative genes of Pseudomonas putida in Caulobacter crescentus

The recombinant plasmid RP4-TOL was transferred into Caulobacter crescentus at a high frequency, and the plasmid was maintained for at least 50 generations. C. crescentus cells which contained RP4-TOL grew on all the aromatic compounds that the plasmid normally allowed Pseudomonas putida to grow on. Reciprocal transfers from C. crescentus donor to P. putida or Escherichia coli recipients were less efficient and occurred at frequencies of approximately 10(-3). Some representative TOL-specified enzymes in cell-free extracts of C. crescentus(RP4-TOL) were inducible, and their levels were similar to those of P. putida. The amounts of mRNA from induced cells of C. crescentus(RP4-TOL) and P. putida(RP4-TOL) were also similar. Moreover, the restriction enzyme digestion maps of RP4-TOL from both C. crescentus and P. putida were the same, indicating that the expression of the TOL genes occurred without any apparent alteration of the gene structure. This suggest that the degradative genes of Pseudomonas spp. can be transferred, maintained, and expressed efficiently in C. crescentus and that the mechanism of transcriptional activation of TOL genes observed in C. crescentus is similar to that of Pseudomonas spp.