A. Camilli et al., USE OF GENETIC-RECOMBINATION AS A REPORTER OF GENE-EXPRESSION, Proceedings of the National Academy of Sciences of the United Statesof America, 91(7), 1994, pp. 2634-2638
An understanding of the patterns of gene expression in response to spe
cific environmental signals can yield insight into a variety of comple
x biological systems such as microbial-host interactions, developmenta
l cycles, cellular differentiation, ontogeny, etc. To extend the utili
ty of the reporter gene fusion approach to such studies, we have const
ructed a gene expression reporter cassette that permits the generation
of transcriptional fusions to tnpR encoding resolvase, a site-specifi
c recombinase of the transposable element gammadelta. Induction of the
transcriptional fusions results in production of resolvase, which in
turn, catalyzes excision of a linked tetracycline-resistance reporter
gene flanked by direct repeats of res, the DNA sequences at which reso
lvase functions. The loss of tetracycline resistance in descendant bac
teria serves as a permanent and heritable marker of prior gene express
ion. This gene fusion approach will allow us to assay the induction of
gene expression in as few as one cell. Additionally, gene expression
can be assayed at a later time and/or different place from the inducin
g environment facilitating the study of gene expression in complex env
ironments such as animal tissues.