Author/Editor		Mulec, Janez; Podlesek, Zdravko; Mrak, Peter; Kopitar, Andreja; Ihan, Alojz; Žgur-Bertok, Darja
Title		A cka-gfp transcriptional fusion reveals that the colicin K activity gene is induced in only 3 percent of the population
Type		članek
Source		J Bacteriol
Vol. and No.		Letnik 185, št. 2
Publication year		2003
Volume		str. 654-9
Language		eng
Abstract		In prokaryotes, oniy a few examples of differential gene expression in cell populations have been described. Colicin production in natura! populations of Escherichia coli, while providing a competitive advantage in the natural habitat, also leads to lysis of the toxin-producing cell. Colicin K synthesis has been found to be induced due to an increase in ppGpp (I. Kuhar, J. P. van Putten, D. Žgur-Bertok, W. Gaastra, and B. J. Jordi, Mol. Microbiol 41:207-216). Using two transcriptional fusions, cka-gfp and cki:gfp, we show that at the single-cell level, the colicin K activity gene cka is expressed in only 3% of the bacterial population upon induction by nutrient starvation. In contrast, the immunity gene cki is expressed in the large majority of the cells. Expression of the cka-gfp fusion in a lexA-defective strain and in a relA spoT mutant strain indicates that differential expression of cka is established primarily at the level of transcription.
Descriptors		COLICINS COLICIN FACTORS TRANSCRIPTION, GENETIC ESCHERICHIA COLI PLASMIDS CLONING, MOLECULAR PROMOTER REGIONS (GENETICS)