Regulatory roles of the global RNA chaperone ProQ in Vibrio cholerae

• Applicant: Professor Dr. Kai Papenfort
• Subject Area: Metabolism, Biochemistry and Genetics of Microorganisms
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 544846468

Gene regulation at the post-transcriptional level is prevalent in all domains of life. In bacteria, the largest group of post-transcriptional regulators are called small RNAs (sRNAs) and usually act by basepairing with target mRNAs to modulate their stability and/or translation. RNA duplex formation between an sRNA and a target is dictated by several auxiliary factors, including RNA binding proteins. Among the latter, Hfq, a hexameric, ring-shaped protein, has been studied most extensively in bacteria, however, other RNA chaperones, e.g. the highly conserved family of ProQ-like proteins, have now been revealed to also interact with sRNAs and to globally modulate gene expression. However, ProQ-mediated gene control has only been studied in few organisms and the underlying regulatory mechanisms are only incompletely understood. In this proposal, we aim to study the role of ProQ in the major human pathogen, Vibrio cholerae. Posttranscriptional gene regulation is key for virulence and biofilm formation in V. cholerae, yet the role of ProQ in these processes has not been addressed. Our preliminary data indicate that ProQ is constitutively expressed in V. cholerae and interacts with hundreds of transcripts, such as the highly abundant FlaX sRNA. Global analysis of RNA-RNA interactions using RIL-Seq (RNA interaction by ligation and sequencing) revealed a large network of ProQ-assisted RNA duplex formation and also indicated a potential role for FlaX and related sRNAs in the regulation of motility-associated genes in V. cholerae. We hypothesize that ProQ and the associated sRNAs affect cell motility by modulating the assembly of the flagellar filament. To address this question, we will use genetic, biochemical, and transcriptomic assays to study the molecular underpinnings driving target regulation by ProQ-dependent sRNAs. Further, we will employ live-cell microscopy to track cell motility in various environments and correlate these data with sRNA and target gene expression. Given that motility plays a crucial role in the lifestyle of V. cholerae (both in the aquatic environment and during host infection), we believe that the outlined research will make an important contribution to understanding the physiology of this major pathogen, but will also provide a more general view on how ProQ affects gene expression in bacteria.

• DFG Programme: Research Grants