title: A cka-gfp transcriptional fusion reveals that the colicin K activity gene is induced in only 3 percent of the population.
abstract: In prokaryotes, only a few examples of differential gene expression in cell populations have been described. Colicin production in natural 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. Zgur-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.
authors.affiliation: Karst Research Institute, Scientific Centre of the Slovenian Academy of Sciences and Arts, Postojna, Slovenia.
authors.forename: Janez
authors.initials: J
authors.lastname: Mulec
authors.forename: Zdravko
authors.initials: Z
authors.lastname: Podlesek
authors.forename: Peter
authors.initials: P
authors.lastname: Mrak
authors.forename: Andreja
authors.initials: A
authors.lastname: Kopitar
authors.forename: Alojz
authors.initials: A
authors.lastname: Ihan
authors.forename: Darja
authors.initials: D
authors.lastname: Zgur-Bertok
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D003087:Colicins / Q000235:genetics* / Q000378:metabolism / Q000494:pharmacology; D004926:Escherichia coli / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism*; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012097:Repressor Proteins / Q000235:genetics; D012697:Serine Endopeptidases / Q000235:genetics; D014158:Transcription, Genetic; D000099160:LexA Repressor Protein
chemical_list: D001426:Bacterial Proteins; D003087:Colicins; D029968:Escherichia coli Proteins; D049452:Green Fluorescent Proteins; D008164:Luminescent Proteins; D011993:Recombinant Fusion Proteins; D012097:Repressor Proteins; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein