The polar landscape of bacterial pathogens and predators.

Precise spatial positioning of cellular constituents is critical for bacterial replication, interactions, and behavior. Rod-shaped bacteria may concentrate molecules and machinery at the cell poles, often by leveraging polar scaffolding proteins to recruit other factors. These typically small proteins can self-assemble into higher-order structures that provide platforms to direct fundamental processes like chromosome segregation, division plane selection, and differentiation. Beyond fundamental cellular processes, polarity is implicated in a wide range of bacterial behaviors, including environmental sensing, intercellular interactions, and motility. In this review, we describe polarity-determining factors and their cellular functions specifically in bacterial predators and in host-associated bacteria, including plant and human pathogens. We aim to highlight pivotal roles cell polarity plays in promoting fitness vis-à-vis the host-microbe and microbe-microbe interface.