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The SOS Response Master Regulator LexA Regulates the Gene Transfer Agent of Rhodobacter capsulatus and Represses Transcription of the Signal Transduction Protein CckA
- Source :
- Journal of Bacteriology. 198:1137-1148
- Publication Year :
- 2016
- Publisher :
- American Society for Microbiology, 2016.
-
Abstract
- The gene transfer agent of Rhodobacter capsulatus (RcGTA) is a genetic exchange element that combines central aspects of bacteriophage-mediated transduction and natural transformation. RcGTA particles resemble a small double-stranded DNA bacteriophage, package random ∼4-kb fragments of the producing cell genome, and are released from a subpopulation (R. capsulatus cells, and the DNA is integrated into the recipient genome though a process that requires homologs of natural transformation genes and RecA-mediated homologous recombination. Here, we report the identification of the LexA repressor, the master regulator of the SOS response in many bacteria, as a regulator of RcGTA activity. Deletion of the lexA gene resulted in the abolition of detectable RcGTA production and an ∼10-fold reduction in recipient capability. A search for SOS box sequences in the R. capsulatus genome sequence identified a number of putative binding sites located 5′ of typical SOS response coding sequences and also 5′ of the RcGTA regulatory gene cckA , which encodes a hybrid histidine kinase homolog. Expression of cckA was increased >5-fold in the lexA mutant, and a lexA cckA double mutant was found to have the same phenotype as a Δ cckA single mutant in terms of RcGTA production. The data indicate that LexA is required for RcGTA production and maximal recipient capability and that the RcGTA-deficient phenotype of the lexA mutant is largely due to the overexpression of cckA . IMPORTANCE This work describes an unusual phenotype of a lexA mutant of the alphaproteobacterium Rhodobacter capsulatus in respect to the phage transduction-like genetic exchange carried out by the R. capsulatus gene transfer agent (RcGTA). Instead of the expected SOS response characteristic of prophage induction, this lexA mutation not only abolishes the production of RcGTA particles but also impairs the ability of cells to receive RcGTA-borne genes. The data show that, despite an apparent evolutionary relationship to lambdoid phages, the regulation of RcGTA gene expression differs radically.
- Subjects :
- 0301 basic medicine
Transcription, Genetic
Molecular Sequence Data
030106 microbiology
Mutant
Microbiology
Rhodobacter capsulatus
03 medical and health sciences
Transduction (genetics)
Bacterial Proteins
Phosphorylation
SOS response
SOS Response, Genetics
Molecular Biology
Prophage
Regulation of gene expression
Genetics
Rhodobacter
Base Sequence
biology
Serine Endopeptidases
Gene Expression Regulation, Bacterial
Articles
biochemical phenomena, metabolism, and nutrition
biology.organism_classification
Gene transfer agent
enzymes and coenzymes (carbohydrates)
Mutation
bacteria
Repressor lexA
Signal Transduction
Subjects
Details
- ISSN :
- 10985530 and 00219193
- Volume :
- 198
- Database :
- OpenAIRE
- Journal :
- Journal of Bacteriology
- Accession number :
- edsair.doi.dedup.....1fbd1da64ee9c79ae6b4e98178c465cb