The bacterial LexA transcriptional repressor
The structure of LexA protein, particularly with respect to distinct conformations that enable repression of SOS genes via specific DNA binding or repressor cleavage during the response to DNA damage, may provide new starting points in the battle against the emergence of bacterial pathogens and the spread of drug resistance among them.
Double locking of an Escherichia coli promoter by two repressors prevents premature colicin expression and cell lysis
IscR stabilizes LexA at the cka promoter after DNA damage thus, preventing its cleavage and inactivation, and this cooperation ensures that suicidal colicin K production is switched on only as a last resort.
Structural insight into LexA–RecA* interaction
The presented model offers a validated insight into the critical step of the bacterial DNA damage response and predicts that LexA in its DNA-binding conformation also forms a complex with RecA* and that the operator DNA sterically precludes interaction withRecA*, which guides the induction of SOS gene expression.
Interconversion between bound and free conformations of LexA orchestrates the bacterial SOS response
It is shown that stimulated self-cleavage of the LexA repressor is prevented by binding to specific DNA operator targets, and, while LexA exhibits diverse dissociation rates from operators, it interacts extremely rapidly with DNA target sites.
Bacterial Transcription Factors: Regulation by Pick "N" Mix.
DNA sampling: a method for probing protein binding at specific loci on bacterial chromosomes
A protocol, DNA sampling, for the rapid isolation of specific segments of DNA, together with bound proteins, from Escherichia coli K-12, by investigating the proteins bound to the colicin K gene regulatory region.
Bacteriophage GIL01 gp7 interacts with host LexA repressor to enhance DNA binding and inhibit RecA-mediated auto-cleavage
- N. Fornelos, M. Butala, V. Hodnik, G. Anderluh, J. Bamford, M. Salas
- BiologyNucleic Acids Research
- 2 July 2015
It is found that gp7 forms a stable complex with LexA that enhances LexA binding to phage and cellular SOS sites and interferes with RecA-mediated auto-cleavage of LexA, the key step in the initiation of the SOS response.
Silencing of DNase Colicin E8 Gene Expression by a Complex Nucleoprotein Assembly Ensures Timely Colicin Induction
- Simona Kamenšek, D. Browning, Z. Podlesek, S. Busby, D. Žgur-Bertok, M. Butala
- BiologyPLoS Genetics
- 1 June 2015
It is reported that AsnC, in concert with LexA, is the key controller of the temporal induction of the DNA degrading colicin E8 gene (cea8), after DNA damage, and it is shown that L-asparagine is an environmental factor that has a marked impact on cea8 promoter regulation.
The Use and Abuse of LexA by Mobile Genetic Elements.
The SOS Response Master Regulator LexA Is Associated with Sporulation, Motility and Biofilm Formation in Clostridium difficile
The construction and characterization of a lexA ClosTron mutant in C. difficile R20291 strain is described, which caused inhibition of cell division resulting in a filamentous phenotype and showed decreased sporulation, a reduction in swimming motility, greater sensitivity to metronidazole, and increased biofilm formation.