Cyclic di-GMP-Mediated Regulation of Gene Transfer and Motility in Rhodobacter capsulatus

Gene transfer agents (GTAs) are virus-like particles that move cellular DNA between cells. In the alphaproteobacteriumRhodobacter capsulatus , GTA production is affected by the activities of multiple cellular regulatory systems, to which we have now added signaling via the second messenger dinucleotide molecule bis-(3′-5′)-cyclic dimeric GMP (c-di-GMP). Similar to the CtrA phosphorelay, c-di-GMP also affectsR. capsulatus flagellar motility in addition to GTA production, with lower levels of intracellular c-di-GMP favoring increased flagellar motility and gene transfer. These findings further illustrate the interconnection of GTA production with global systems of regulation inR. capsulatus , providing additional support for the notion that the production of GTAs has been maintained in this and related bacteria because it provides a benefit to the producing organisms.