Peer pressure from a Proteus mirabilis self-recognition system controls participation in cooperative swarm motility

Area of Science:

• Microbiology
• Bacterial behavior
• Social interactions in bacteria

Background:

• Proteus mirabilis is an opportunistic pathogen.
• Bacterial kin discrimination models typically involve lethal antagonism via toxin delivery.
• Existing models do not fully explain non-lethal self-recognition systems.

Purpose of the Study:

• To elucidate the non-lethal Ids self-recognition system in Proteus mirabilis.
• To understand how this system mediates exclusion of non-self cells from swarming colonies.
• To connect non-lethal recognition mechanisms to the lifecycle of P. mirabilis swarm colonies.

Main Methods:

• Observational studies of swarming colonies of different P. mirabilis strains.
• Analysis of gene expression changes in non-self cells induced into a growth-arrested state.
• Investigation of the role of the stringent response in mediating this non-lethal recognition.

Main Results:

• P. mirabilis employs a non-lethal self-recognition system (Ids) to exclude non-kin cells from swarming colony edges.
• Non-self cells are transiently induced into a growth-arrested state, reducing expression of genes for protein synthesis, virulence, and motility.
• Temporary activation of the stringent response is essential for entering this growth-arrested state, which also confers antibiotic tolerance.

Conclusions:

• The Ids system represents an expansion of bacterial kin discrimination paradigms beyond lethal antagonism.
• This non-lethal recognition mechanism plays a crucial role in the social behavior and lifecycle of P. mirabilis swarm colonies.
• Understanding this system clarifies the intricate interplay between bacterial recognition and cooperative behaviors.