Effect of LexA on Chromosomal Integration of CTXÏ in Vibrio cholerae.
J Bacteriol
; 198(2): 268-75, 2016 01 15.
Article
in En
| MEDLINE
| ID: mdl-26503849
ABSTRACT
UNLABELLED The genesis of toxigenic Vibrio cholerae involves acquisition of CTXÏ, a single-stranded DNA (ssDNA) filamentous phage that encodes cholera toxin (CT). The phage exploits host-encoded tyrosine recombinases (XerC and XerD) for chromosomal integration and lysogenic conversion. The replicative genome of CTXÏ produces ssDNA by rolling-circle replication, which may be used either for virion production or for integration into host chromosome. Fine-tuning of different ssDNA binding protein (Ssb) levels in the host cell is crucial for cellular functioning and important for CTXÏ integration. In this study, we mutated the master regulator gene of SOS induction, lexA, of V. cholerae because of its known role in controlling levels of Ssb proteins in other bacteria. CTXÏ integration decreased in cells with a ΔlexA mutation and increased in cells with an SOS-noninducing mutation, lexA (Ind(-)). We also observed that overexpression of host-encoded Ssb (VC0397) decreased integration of CTXÏ. We propose that LexA helps CTXÏ integration, possibly by fine-tuning levels of host- and phage-encoded Ssbs. IMPORTANCE Cholera toxin is the principal virulence factor responsible for the acute diarrheal disease cholera. CT is encoded in the genome of a lysogenic filamentous phage, CTXÏ. Vibrio cholerae has a bipartite genome and harbors single or multiple copies of CTXÏ prophage in one or both chromosomes. Two host-encoded tyrosine recombinases (XerC and XerD) recognize the folded ssDNA genome of CTXÏ and catalyze its integration at the dimer resolution site of either one or both chromosomes. Fine-tuning of ssDNA binding proteins in host cells is crucial for CTXÏ integration. We engineered the V. cholerae genome and created several reporter strains carrying ΔlexA or lexA (Ind(-)) alleles. Using the reporter strains, the importance of LexA control of Ssb expression in the integration efficiency of CTXÏ was demonstrated.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Bacterial Proteins
/
Serine Endopeptidases
/
Virus Integration
/
Genome, Viral
/
Genome, Bacterial
Language:
En
Journal:
J Bacteriol
Year:
2016
Document type:
Article
Affiliation country:
India