Type VI secretion regulation: crosstalk and intracellular communication

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Molecular Biology

Background:

• Type VI secretion systems (T6SSs) are crucial for bacterial virulence, enabling protein transport into host cells or the environment.
• TSSCs are tightly regulated and interconnected with other virulence determinants, including type III secretion systems, quorum sensing (QS), and flagella synthesis.
• Pathogenic bacteria like *Salmonella enterica*, *Edwardsiella tarda*, *Aeromonas hydrophila*, *Vibrio cholerae*, and *Pseudomonas aeruginosa* rely on complex regulatory networks.

Purpose of the Study:

• To investigate the crosstalk proteins (global regulators) that link T6SSs to other virulence determinants in five key bacterial pathogens.
• To identify common regulatory mechanisms governing T6SS expression and its coordination with other virulence factors.
• To elucidate the integral communication network essential for bacterial pathogenesis.

Main Methods:

• Comparative analysis of regulatory elements across five selected bacterial pathogens.
• Identification of common transcriptional regulators (TRs) involved in T6SS regulation.
• Examination of regulatory connections between T6SSs and other virulence systems like QS and flagella synthesis.

Main Results:

• Several common transcriptional regulators (TRs) were identified that connect T6SSs to other virulence determinants.
• Key regulators include two-component systems (e.g., PhoPQ), sigma54 (σ(54)) and its dependent regulators (e.g., VasH), and quorum sensing (QS) regulators.
• These findings highlight a conserved communication network coordinating virulence strategies in these pathogens.

Conclusions:

• A complex communication network exists between T6SSs and other virulence factors in bacterial pathogens.
• Transcriptional regulators play a central role in integrating T6SS regulation with other essential virulence pathways.
• Understanding this network is critical for defining the core components of bacterial pathogenesis and for developing novel therapeutic strategies.