Double take: A dual-functional Hypr GGDEF synthesizes both cyclic di-GMP and cyclic GMP—AMP to control predation in Bdellovibrio bacteriovorus

Bacteria possess well-orchestrated signal transduction mechanisms, such as nucleotide second messengers, to tune gene regulation for adaption and survival in variety of environmental conditions [1,2]. Cyclic di-AMP plays a crucial role in DNA repair, cell wall homeostasis, osmotic homeostasis, sporulation, and biofilm formation in predominantly gram-positive bacteria [12,13]. Whereas the WT Bd0367 enzyme primarily synthesizes 3′3′-cGAMP in vitro, generation of the Bd0367S124D mutant enzyme rendered it solely able to synthesize c-di-GMP. [...]complementation of the Δbd0367 mutant with the bd0367S124D allele abolished in vivo cGAMP synthesis and did not restore functional gliding motility or escape from prey cells [18]. The signals that regulate synthesis of c-di-GMP or cGAMP by Bd0367 are unknown. https://doi.org/10.1371/journal.pgen.1010263.g002 The predatory bacterium B. bacteriovorus undergoes a complex life cycle involving several sequential events: hunt and attachment to prey, prey entry, intracellular growth forming a bdelloplast, replication inside the bdelloplast, rupture, and exit of the prey cell [22,23].