Involvement of Escherichia coli FIS protein in maintenance of bacteriophage mu lysogeny by the repressor: control of early transcription and inhibition of transposition.
The Escherichia coli FIS (factor for inversion stimulation) protein has been implicated in assisting bacteriophage Mu repressor, c, in maintaining the lysogenic state under certain conditions. In a fis strain, a temperature-inducible Mucts62 prophage is induced at lower temperatures than in a wild-type host (M. Bétermier, V. Lefrère, C. Koch, R. Alazard, and M. Chandler, Mol. Microbiol. 3:459-468, 1989). Increasing the prophage copy number rendered Mucts62 less sensitive to this effect of the fis mutation, which thus seems to depend critically on the level of repressor activity. The present study also provides evidence that FIS affects the control of Mu gene expression and transposition. As judged by the use of lac transcriptional fusions, repression of early transcription was reduced three- to fourfold in a fis background, and this could be compensated by an increase in cts62 gene copy number. c was also shown to inhibit Mu transposition two- to fourfold less strongly in a fis host. These modulatory effects, however, could not be correlated to sequence-specific binding of FIS to the Mu genome, in particular to the strong site previously identified on the left end. We therefore speculate that a more general function of FIS is responsible for the observed modulation of Mu lysogeny.
Bétermier
M
M
Molecular Genetics and Microbiology Laboratory, Centre National de la Recherche Scientifique UPR 9007, Toulouse, France.
Poquet
I
I
Alazard
R
R
Chandler
M
M
D010583:Bacteriophage mu / Q000235:genetics*; D001483:Base Sequence; D015153:Blotting, Western; D002352:Carrier Proteins / Q000378:metabolism*; D016384:Consensus Sequence; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D034982:Integration Host Factors; D008242:Lysogeny; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009838:Oligodeoxyribonucleotides / Q000737:chemistry; D009876:Operon; D011485:Protein Binding; D012333:RNA, Messenger / Q000235:genetics; D012045:Regulatory Sequences, Nucleic Acid; D012097:Repressor Proteins / Q000235:genetics*; D014158:Transcription, Genetic
D002352:Carrier Proteins; D004251:DNA Transposable Elements; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D035021:Factor For Inversion Stimulation Protein; D034982:Integration Host Factors; D009838:Oligodeoxyribonucleotides; D012333:RNA, Messenger; D012097:Repressor Proteins; C440502:integration host factor, E coli