Signaling and Regulatory Network in Bacteria

Research Overview

Living cells maintain cellular activity and composition for an optimal fitness, whether growth conditions are constant or changing. The homeostatic balance and its adaptation to new growth conditions are controlled by appropriate gene expression. It is ensured by strict regulations of RNA quantities and mRNA translation. RNA are essential partners of protein expression, as a component of ribosomes, by transferring amino-acyl groups to synthetized proteins and by being carbon copies of gene for translation. They are also intrinsic regulators that modify gene expression and protein activity. High throughput sequencing experiments have revealed hundreds of RNA regulatory elements per bacterial genome and yet the function of most of them remains unknown. Our goal is to decipher RNA-dependent regulatory networks including transcription and post-transcription events.

Our model systems

Our current work focuses on Staphylococcus aureus and Salmonella Enterica. For the latter, see “Transcription management and epigenetic regulation in Salmonella”

Staphylococcus aureus is ne of the most frequently reported antibiotic-resistant bacteria; this opportunistic pathogen belongs to the ESKAPE group, an acronym given to six pathogens responsible for nosocomial infections that that pose a threat to health worldwide. Despite recent reports of efficient prophylactic measures, S. aureus remains a leading cause of community- and healthcare-associated diseases ranging from minor skin infection to fatal bacteremia. Its “success” as a pathogen is due to the expression of numerous virulence factors, a high adaptability to many biotopes, and to the emergence of multidrug-resistant strains. Our experimental approaches are mainly bacterial genetics, genomics and physiology.

Research highlights

Our objective is to understand adaptation of bacteria, to identify regulatory elements and to decipher their role with a focus on the function of regulatory RNAs (sRNAs). We developed several strategies to identify sRNA and sRNA targets. Using biocomputing and experimental approaches, we have contributed to establish the inventory of regulatory RNAs in Vibrio species and S. aureus. Over the past 50 years, researchers have established a complex network of regulations under the control of sigma and transcriptional factors. We are now unraveling another level complexity associating sRNAs, acting mainly post-transcriptionally and contributing to fine-tune gene expression. Our past work highlighting the numerous metabolic genes controlled by the RsaE sRNA in S. aureus is an example.