Structural and functional analysis of proteins involved in the C-DI-GMP network of the predatory bacterium \(Bdellovibrio\) \(bacteriovirus\)

Meek, Richard William (2018). Structural and functional analysis of proteins involved in the C-DI-GMP network of the predatory bacterium \(Bdellovibrio\) \(bacteriovirus\). University of Birmingham. Ph.D.

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Abstract

\(Bdellovibrio\) \(bacteriovorus\) HD 100 is a σ-proteobacterium that predates on Gram-negative bacteria. The lifecycle of \(Bdellovibrio\) \(bacteriovorus\) is complex and regulated in part by the cyclic nucleotide, c-di-GMP. Gene knockouts of diguanylate cyclases reveal discrete phenotypes in \(Bdellovibrio\) at different time points of predation. This thesis presents the first structure of the \(Bdellovibrio\) diguanylate cyclase, Bd0742 in an inhibitory conformation. Bd0742 mediates invasion but the mechanism of its regulation was unknown. Our structure suggests that an N-terminal tail attached to the forkhead-associated domain of Bd0742 regulates diguanylate cyclase activity via self-binding. We present structural and biochemical evidence demonstrating that the Nterminal tail regulates Bd0742 activity. An active mutant of Bd0742 was produced by introduction of a disulphide bond. We also solved the structure of the glucose-6-phosphate isomerase Bd07 41. Bd07 41 likely catalyses isomerization of glucose-6-phosphate and of fructose-6-phosphate. Finally, this thesis presents a structure of a region of the degenerate diguanylate cyclase, Bd3125. Mutant strains deficient of Bd3125 invade prey more slowly. The Bd3125 structure reveals that a previously cryptic domain is a GAF (cGMP-specific phosphodiesterase, Adenylyl cyclases and FhiA) domain, with a potential role in controlling invasion speed.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):