Regulation of Differentiation in Caulobacter

Stanford University, Stanford CA

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Abstract

[unreadable] DESCRIPTION (provided by applicant): Our goal is to determine how multiple regulatory mechanisms are linked together to form a system that controls polar morphogenesis and cell cycle progression in Caulobacter crescentus. The completion of the annotated genome sequence of 3767 genes, ease of synchrony and genetic manipulation, and full genome microarray analysis have allowed us to explore the global regulatory network that controls a bacterial cell cycle. Temporally regulated transcription, signal transduction mediated by the two component family of proteins, and temporally controlled proteolytic events all contribute to the control of the Caulobacter cell cycle. In addition, we discovered that regulatory proteins that control the cell cycle and asymmetry at cell division are dynamically localized to cell poles. We will now determine why and how these proteins are dynamically positioned to specific sites in the cell. Temporally controlled clearance from the cell of the components of the polar pili, flagellum, and chemotaxis complex, and the regulatory proteins that regulate their biogenesis, is critical for the establishment of asymmetry. We will determine the mechanisms that are used to control the proteolysis of both structural and regulatory proteins at critical times in the cell cycle. Finally, we have found that of 550 genes whose transcription is regulated during the cell cycle, 25 percent are controlled by the CtrA response regulator. We will now identify the global regulators that control temporally expressed genes that are independent of CtrA control. We will also identify the groups of genes that are controlled by 5 new regulatory proteins that are themselves directly controlled by CtrA at specific times in the cell cycle in an attempt to construct a serially connected network that integrates the genetic circuitry. The proposed experiments will explore individual regulatory mechanisms in depth while determining how they form a three-dimensional network for the control of the cell cycle. [unreadable] [unreadable]