Genetic evidence for the existence of a repressor that modulates colicin D expression on plasmid ColD-CA23.
The plasmid ColD-CA23, a high copy number plasmid of 5.12 kb, contains genes for colicin D (cda), for immunity colicin D (cdi), and for a lysis function (cdl). These genes are arranged on a contiguous 2.4 kb fragment in the following sequence: cda, cdi, cdl. They are transcribed in two operons, one transcribing cda and cdl from a SOS inducible promoter, the other transcribing cdi in the opposite direction. The expression of cda and cdl is modulated by a repressor, cdr, which is encoded on the same transcript as cda and cdl. In the absence of this repressor, transcription from the SOS inducible colicin D promoter is exceptionally strong and leads to protein contents up to 50% of total cellular proteins. This autoregulative repressor is a new finding in the control mechanisms of expression of colicins. We have also identified the gene product of cdl to be a 10,000 dalton protein.
Ghersa
P
P
Département de Biochimie, Université de Genève, Switzerland.
Lurz
R
R
Dobrinski
B
B
Deshusses
J
J
Belet
M
M
Frey
J
J
D001665:Binding Sites; D003087:Colicins / Q000235:genetics*; D004262:DNA Restriction Enzymes; D012321:DNA-Directed RNA Polymerases / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D005786:Gene Expression Regulation; D005796:Genes; D005798:Genes, Bacterial; D009876:Operon; D010957:Plasmids; D011485:Protein Binding; D012097:Repressor Proteins / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D014158:Transcription, Genetic
D003087:Colicins; D012097:Repressor Proteins; D014157:Transcription Factors; D012321:DNA-Directed RNA Polymerases; D004262:DNA Restriction Enzymes