Date of Award

August 2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy

Department

Biological Sciences

First Advisor

Ching Hong Yang

Committee Members

Sonia Bardy, Sergei Kuchin, Heather Owen, Douglas Steeber

Keywords

c-di-GMP, Dickeya dadantii, diguanylate cyclase, T3SS

Abstract

The enterobacterium, Dickeya dadantii, is an opportunistic bacterial pathogen that causes disease in many plants. C-di-GMP is a ubiquitous bacterial second messenger, regulating multiple cellular behaviors through several c-di- GMP-associated components. Here, we identified a novel transcriptional regulator named CdeR that regulates T3SS in a c-di-GMP-dependent manner. GcpD is a diguanylate cyclase responsible for the synthesis of c-di-GMP. Compared to a gcpD mutant, the gcpD and cdeR double mutant exhibited a reduced T3SS expression. In addition, we found that, under the gcpD mutant background, CdeR regulates T3SS by manipulating intracellular c-di-GMP levels, involving an additional diguanylate cyclase GcpL upregulated by CdeR. This is the first report that uncovers CdeR as a transcriptional regulator involved in the regulation of T3SS. A model is proposed on how CdeR regulates T3SS expression by manipulating the c-di-GMP network.

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