Analysis of βLR16 subclones
To assess the potential roles of the putative metallopeptidase and response regulator genes in
resistance, subclones were generated and carbenicillin resistance was assayed in an E. coli
EPI300 background. Analysis of subclones harboring the metallopeptidase gene alone
(pCRC01UVRA), the two genes together (pCRC02UVRA), and the response regulator gene
alone (pCRC03UVRA) revealed that the response regulator gene was necessary and sufficient
to confer carbenicillin resistance on the E. coli host (Table 3). No resistance was seen with the
metallopeptidase alone, while the combination of the two genes yielded a resistance profile that
was the same as the regulator gene alone. Based on these results, we hypothesized that the twocomponent
regulator gene may be altering gene expression in E. coli in a way that results in elevated,
specific resistance to carbenicillin.