ParP prevents dissociation of CheA from chemotactic signaling arrays and tethers them to a polar anchor

Abstract

Bacterial chemotaxis proteins are organized into ordered arrays. Inperitrichous organisms, such as Escherichia coli, stochastic assembly processes are thought to account for the placement of chemo-taxis arrays, which are nonuniformly distributed. In contrast, wepreviously found that chemotactic signaling arrays in polarly flagellated vibrios are uniformly polar and that array localization isdependent on the ParA-like ATPase ParC. However, the processesthat enable ParC to facilitate array localization have not been described. Here, we show that a previously uncharacterized protein,ParP, interacts with ParC and that ParP is integral to array localization in Vibrio parahaemolyticus. ParC's principal contribution tochemotaxis appears to be via positioning of ParP. Once recruitedto the pole by ParC, ParP sequesters arrays at this site by capturingand preventing the dissociation of chemotactic signaling protein(CheA). Notably, ParP also stabilizes chemotactic protein complexes in the absence of ParC, indicating that some of its activityis independent of this interaction partner. ParP recruits CheA viaCheA's localization and inheritance domain, a region found only inpolarly flagellated organisms that encode ParP, ParC, and CheA.Thus, a tripartite (ParC-ParP-CheA) interaction network enablesthe polar localization and sequestration of chemotaxis arrays inpolarly flagellated organisms. Localization and sequestration ofchemotaxis clusters adjacent to the flagella-to which the chemo-tactic signal is transmitted-facilitates proper chemotaxis as wellas accurate inheritance of these macromolecular machines.