IDENTIFICATION OF AN ASYMMETRICALLY LOCALIZED SENSOR HISTIDINE KINASERESPONSIBLE FOR TEMPORALLY AND SPATIALLY REGULATED TRANSCRIPTION

Caulobacter crescentus undergoes asymmetric cell division, resulting i n a stalked cell and a motile swarmer cell. The genes encoding externa l components of the flagellum are expressed in the swarmer compartment of the predivisional cell through the localized activation of the tra nscription factor FlbD. The mechanisms responsible for the temporal an d spatial activation of FlbD were determined through identification of FlbE, a histidine kinase required for FlbD activity. FlbE is asymmetr ically distributed in the predivisional cell. It is located at the pol e of the stalked compartment and at the site of cell division in the s warmer compartment. These findings suggest that FlbE and FlbD are acti vated in response to a morphological change in the cell resulting from cell division events.