Flagellar assembly is complex and coupled to the controlled expression of more than 70 genes in the flagellar and chemotaxis regulon. It takes many cell generations to assemble a completed flagellum. For 25 years my lab has investigated mechanisms that couple flagellar gene expression to assembly. In addition, about 20 regulators have been identified that couple induction or inhibition of flagellar synthesis to different environmental conditions that are sensed by numerous global regulatory pathways in the cell. The focus of this grant application is to determine mechanisms involved in localized transcription and translation mechanisms of flagellar genes at the base of the flagellar structures in the cytoplasm. The research will also determine how a few specific proteins are selected from the thousands present in the cytoplasm and targeted for secretion. How does the coordinate the assembly of multiple structures within the same cell? Our preliminary data suggests that coordinating the assembly of multiple structures within an individual cell occurs by compartmentalization in 3-dimensional space to generate independent construction sites in the cell.