Multiple regulators control capsular polysaccharide production in Vibrio parahaemolyticus.

Area of Science:

• Microbiology
• Molecular Biology
• Bacterial Pathogenesis

Background:

• Vibrio parahaemolyticus exhibits phase variation between translucent (TR) and opaque (OP) colony morphologies.
• Opaque colonies produce more capsular polysaccharide (CPS) than translucent colonies, controlled by the LuxR-type transcriptional activator OpaR.
• CPS production is linked to the scrABC signaling pathway and GGDEF-EAL motif proteins.

Purpose of the Study:

• To identify genes involved in CPS production in V. parahaemolyticus.
• To investigate the regulation of CPS gene expression.
• To elucidate the roles of novel transcriptional regulators in CPS production and phase variation.

Main Methods:

• Transposon mutagenesis to identify CPS-related genes.
• Reporter gene fusions (cpsA) to quantify transcriptional changes.
• Analysis of mutant phenotypes in pellicle formation and biofilm assays.
• Characterization of novel regulators CpsR and CpsS.

Main Results:

• Eleven genes in the cps locus were identified; mutations abolished opacity and CPS production.
• cpsA transcription was approximately 10-fold higher in OP (opaR+) compared to TR (deltaopaR) strains.
• CpsR acts as an activator in the scrABC pathway, while CpsS acts as a repressor, influencing cpsA expression.
• CpsS mutants showed significantly elevated cpsA transcription, dependent on CpsR and OpaR.

Conclusions:

• A complex regulatory network involving OpaR, CpsR, and CpsS controls CPS production in V. parahaemolyticus.
• This network integrates signaling pathways to modulate bacterial morphology and biofilm formation.
• Understanding these regulators is crucial for controlling V. parahaemolyticus pathogenesis and biofouling.