Molecular and transcriptomic studies of quorum sensing in Chromobacterium subtsugae

Previous research had shown that the CdeAB-OprM efflux system contributes to antibiotic resistance in C. subtsugae and that this system is controlled by the CviI-R QS system. Here, we show that the cdeAB-oprM genes are repressed by an adjacently encoded TetR-family transcriptional regulator, CdeR. Our research also demonstrates that CviR and CdeR independently regulates the expression of cdeAB-oprM genes by directly interacting with the cdeA promoter. CviR requires a lux-box and CdeR requires a binding site in the cdeA promoter. Single-cell level activity of cdeA promoter revealed that the expression is bimodal in presence of CviR and CdeR. Our result provides a basis for understanding the molecular mechanism of cdeAB-oprM gene expression and its implication on the production of heterogeneous phenotype leading to bet hedging.CviR can respond to a variety of AHLs in addition to C6-HSL. Previously, it was shown that the promiscuous activation of CviR by B. thailandensis AHLs provides a competitive advantage to C. subtsugae. Here, we show that B. thailandensis AHLs activate transcription of dozens of genes in C. subtsugae, including the hcnABC genes coding for production of hydrogen cyanide. We also demonstrate that the cross-induction of hydrogen cyanide by B. thailandensis AHLs provides a competitive advantage to C. subtsugae. Our results also show that C. subtsugae can respond to non-cognate C8-HSL signal and upregulate 53 genes that are not present in the C6-HSL regulon. These genes are predicted to play a role in amino acid metabolism, motility, conjugation, antibiotic resistance, and many more. Our results provide evidence for a novel function of the quorum sensing system. C. subtusgae can sense the presence of competitors by through non-cognate AHL molecules and express genes to design an attack against those competitors.

Grantor dc:publisher

University of Kansas

Year dc:date.issued

2023

Author dc:creator

• Koirala, Pratik

Advisor dc:contributor.advisor

• Chandler, Josephine R

• Microbiology
• Antibiotic resistance
• Chromobacterium
• gene expression
• Quorum sensing

Statement dc:rights

• Copyright held by the author.

Language dc:language.iso

en

Dc Identifier Other

http://dissertations.umi.com/ku:19154

OAI identifier oai:identifier

oai:kuscholarworks.ku.edu:1808/38763