Identification of type VI secretion system toxic effectors using adaptors as markers

Area of Science:

• Microbiology
• Genomics
• Molecular Biology

Background:

• Type VI secretion systems (T6SS) deliver toxic effectors involved in bacterial competition and host pathogenesis.
• Predicting T6SS effectors is difficult due to their diverse sequences and functions.

Purpose of the Study:

• To systematically identify putative T6SS toxic effectors in prokaryotic genomes.
• To develop a method for discovering novel T6SS effectors based on genomic context.

Main Methods:

• Analysis of genomic proximity between known T6SS adaptor proteins (DUF1795, DUF2169, DUF4123) and their cognate effectors.
• Identification of a potential novel adaptor protein (PRK06147).
• Systematic identification of putative effectors by examining genes adjacent to 5297 adaptor genes.

Main Results:

• Adaptor protein genes are often located near T6SS spike proteins (VgrG, PAAR) and effector genes.
• 1356 putative effector genes from 92 families were identified adjacent to adaptor genes.
• Two-thirds of the identified putative effectors were previously annotated as hypothetical or of unknown function.

Conclusions:

• T6SS adaptor protein families serve as effective markers for identifying T6SS toxic effectors.
• This genomic context approach significantly expands the repertoire of known T6SS effectors.
• The findings facilitate the discovery of novel effectors, advancing our understanding of T6SS functions.