Establishing polar identity in gram-negative rods

•HubP tethers chromosome origins and chemotactic signaling arrays to Vibrio cholerae poles.•HubP and ParC ensure reliable inheritance of chemotactic signaling arrays.•Aggregation of PopZ at new poles in Caulobacter crescentus is coupled to accumulation of ParA.•A nucleotide and dimerization-dependent MipZ gradient guides C. crescentus division.•Small GTPases, response regulators, and motor ATPases underlie Myxococcus xanthus polarity.

In rod shaped bacteria, numerous cellular components are targeted to the cell poles, and such localization is often important for optimal function. In particular, recognition of poles is often linked to division site selection, chromosome segregation, chemotactic signaling, and motility. Recent advances in understanding polarity include identification of a Vibrio cholerae protein that mediates polar localization of a chromosome origin and chemotaxis clusters, as well as a downstream protein that contributes solely to localization of chemotaxis proteins. In Caulobacter crescentus, the molecular mechanisms by which polar determinants and effectors are localized, and the key roles for nucleotide-dependent switches, have been defined. Finally, roles for, and interactions between, factors that mediate environmentally determined polarity in Myxococcus xanthus have recently been characterized.