Cyclic Diguanylate, A Novel Secondary Messenger in Bacteria

University Of Wyoming, Laramie WY

Investigators

Abstract

The numerous conserved protein domains of unknown function have been revealed through microbial genomics, which suggests that significant areas of microbial physiology, metabolism and behavior remain unexplored. This research is aimed at investigating functions of proteins containing GGDEF and EAL domains that are broadly distributed in diverse bacteria. The GGDEF and EAL domains are involved in synthesis and hydrolysis of the unusual nucleotide, cyclic diguanylate, c-di-GMP. The main hypothesis of this project is that c-di-GMP is an important underappreciated second messenger in bacteria. The long-term goals of the project are to elucidate the role of c-di-GMP and to reveal the mechanisms by which it operates using the metabolically versatile proteobacterium, Rhodobacter sphaeroides, as a model. Preliminary data indicate that R. sphaeroides contains enzymes involved in both synthesis (diguanylate cyclases) and hydrolysis (phosphodiesterases) of c-di-GMP. Initial emphasis of this project will be placed on two R. sphaeroides c-di-GMP-specific phosphodiesterases, designated BphG and BphH, which contain phytochrome-type domains and are likely to represent photoreceptors of unique structure. The depletion of the intracellular pool of c-di-GMP in R. sphaeroides results in specific changes in the R. sphaeroides transcriptome. Uncovering mechanisms by which c-di-GMP affects gene expression is another aim of this project. A combination of molecular genetic, transcriptomics and biochemical approaches will be employed to address these questions. This research will fill an apparent void in our understanding of the bacterial cell resulting from an oversight of a potentially important second messenger, c-di-GMP. Elucidation of the role of c-di-GMP is anticipated to have a significant effect on the field of signal transduction in various bacteria, including agriculturally, environmentally and medically important species. This project will provide ample opportunities for interdisciplinary training of high school, undergraduate, graduate and postdoctoral students.