Evolutionary Remodeling of Bacterial Motility Checkpoint Control

Area of Science:

• Evolutionary biology
• Systems biology
• Microbial genetics

Background:

• Regulatory networks are crucial for genotype-phenotype relationships.
• Evolutionary plasticity mechanisms in these networks are not well understood.
• Bacterial flagellar networks are complex and vital for motility.

Purpose of the Study:

• To investigate the adaptability of complex regulatory networks.
• To understand the mechanisms driving evolutionary changes in bacterial motility.
• To explore the role of specific network topologies in adaptation.

Main Methods:

• Experimental evolution using selection for enhanced bacterial motility in a porous environment.
• Identification of adaptive mutations in flagellar motor components and regulatory proteins.
• Computer simulations to model network dynamics and evolutionary tuning.

Main Results:

• Phenotypic changes in motility were driven by adaptive mutations in multiple proteins.
• A single mechanism, remodeling of the flagellar gene expression checkpoint, explained the adaptation.
• The 'bow-tie' topology of the checkpoint was found to facilitate evolutionary tuning of motility versus growth trade-offs.

Conclusions:

• Remodeling of regulatory checkpoints is a key mechanism for evolutionary adaptation.
• Bow-tie regulatory motifs enhance the ability to tune cost-benefit trade-offs.
• These motifs likely play a general role in the evolutionary adaptation of cellular networks.