Cyclic nucleotides, cyclic nucleotide phosphodiesterase, and development in Myxococcus xanthus.

Exogenous cyclic nucleotide phosphodiesterase (PD) accelerated fruiting body (FB) formation and increased territory size of aggregates in Myxococcus xanthus. Both guanosine 3'5'-monophosphate (cGMP) and guanosine 5'-monophosphate (GMP) were antagonistic to the PD effect. Adenosine 3'5'-monophosphate (cAMP) increases FB numbers twofold in the absence but not in the presence of PD. PD induction is not affected by methionine or isoleucine, which inhibit, or by threonine, which stimulates, FB formation. There is an increase and subsequent decrease in cAMP levels during early glycerol-induced microcyst development but 10 mM theophylline or caffeine not only inhibited microcyst development but induced germination in the presence of glycerol. On the basis of these results and the reports of other investigators a tentative model is proposed based on a dual role for cyclic nucleotides in the development in M. xanthus.