Deciphering the Salmonella T6SS toolkit: two decades of research decoding a versatile bacterial weapon

Area of Science:

• Microbiology
• Bacterial Pathogenesis
• Genomics

Background:

• The Type VI Secretion System (T6SS) is a key factor in bacterial fitness and virulence for Gram-negative bacteria.
• Five T6SS gene clusters (SPI-6, SPI-19, SPI-20, SPI-21, SPI-22) exist in Salmonella, influencing genome evolution across serotypes.

Purpose of the Study:

• To review current knowledge on T6SS in Salmonella biology.
• To highlight advancements in T6SS research over the past two decades.
• To discuss T6SS effector proteins, regulatory mechanisms, and future research directions.

Main Methods:

• Literature review of existing studies on Salmonella T6SS.
• Analysis of T6SS gene cluster distribution and effector protein repertoire.
• Examination of regulatory mechanisms controlling T6SS expression.

Main Results:

• T6SS gene cluster gain/loss events shape Salmonella serotype evolution.
• Differential T6SS distribution and diverse effectors impact environmental fitness and pathogenicity.
• Host-derived cues and regulators play a role in controlling T6SS expression.

Conclusions:

• Understanding T6SS in Salmonella is vital for comprehending bacterial biology and host colonization.
• Further research on T6SS mechanisms can reveal how Salmonella thrives in competitive environments.
• Critical analysis of conflicting reports and future directions are provided.