title: The SOS response affects thermoregulation of colicin K synthesis.
abstract: Temperature is one of the key environmental parameters affecting bacterial gene expression. This study investigated the effect of temperature on synthesis of Escherichia coli colicins E1, K, N and E7 as well as the molecular basis underlying thermoregulation of the colicin K activity gene cka. The results of our study show that synthesis of the investigated colicins is higher at 37 degrees C than at 22 degrees C and that temperature regulates cka expression at the level of transcription. We propose that the SOS response indirectly regulates thermoregulation of colicin K (and possibly of the other examined colicins). Two LexA dimers bind cooperatively with high affinity to the two overlapping LexA boxes in a temperature-independent manner. At 22 degrees C the relative degree of repression is higher as a result of less LexA cleavage due to a slower growth rate, while at 37 degrees C the extent of LexA cleavage is higher due to a higher growth rate. Thermoregulation of colicin synthesis is an additional example of the connection between the SOS regulon and cell physiology.
authors.affiliation: Department of Biology, Biotechnical Faculty, University of Ljubljana, Ljubljana, Slovenia.
authors.forename: Matej
authors.initials: M
authors.lastname: Butala
authors.forename: Zdravko
authors.initials: Z
authors.lastname: Podlesek
authors.forename: Darja
authors.initials: D
authors.lastname: Zgur-Bertok
mesh_terms: D001426:Bacterial Proteins / Q000378:metabolism; D003087:Colicins / Q000096:biosynthesis*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism*; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D009875:Operator Regions, Genetic; D010957:Plasmids; D013014:SOS Response, Genetics; D012697:Serine Endopeptidases / Q000378:metabolism; D013696:Temperature; D000099160:LexA Repressor Protein
chemical_list: D001426:Bacterial Proteins; D003087:Colicins; D012697:Serine Endopeptidases; D000099160:LexA Repressor Protein