Cyclic Diguanylate (CdiGMP)

Cyclic di-GMP is a second messenger used in signal transduction in a wide variety of bacteria. Cyclic di-GMP is not known to be used by eukaryotes or archaea. The biological role of cyclic di-GMP was first uncovered when it was identified as an allosteric activator of a cellulose synthase found in in Gluconacetobacter xylinus.

In structure, it is a tiny cycle of RNA, containing only two guanine bases linked by ribose and phosphate.

In bacteria, certain signals are communicated by synthesizing or degrading cyclic di-GMP. Cyclic di-GMP is synthesized by proteins with diguanylate cyclase activity. These proteins typically have a characteristic GGDEF motif, which refers to a conserved sequence of five amino acids. Degradation of cyclic di-GMP is effected by proteins with phosphodiesterase activity. These proteins have either an EAL or an HD-GYP amino acid motif.