title: Cyclic Di-GMP phosphodiesterases RmdA and RmdB are involved in regulating colony morphology and development in Streptomyces coelicolor.
abstract: Cyclic dimeric GMP (c-di-GMP) regulates numerous processes in Gram-negative bacteria, yet little is known about its role in Gram-positive bacteria. Here we characterize two c-di-GMP phosphodiesterases from the filamentous high-GC Gram-positive actinobacterium Streptomyces coelicolor, involved in controlling colony morphology and development. A transposon mutation in one of the two phosphodiesterase genes, SCO0928, hereby designated rmdA (regulator of morphology and development A), resulted in decreased levels of spore-specific gray pigment and a delay in spore formation. The RmdA protein contains GGDEF-EAL domains arranged in tandem and possesses c-di-GMP phosphodiesterase activity, as is evident from in vitro enzymatic assays using the purified protein. RmdA contains a PAS9 domain and is a hemoprotein. Inactivation of another GGDEF-EAL-encoding gene, SCO5495, designated rmdB, resulted in a phenotype identical to that of the rmdA mutant. Purified soluble fragment of RmdB devoid of transmembrane domains also possesses c-di-GMP phosphodiesterase activity. The rmdA rmdB double mutant has a bald phenotype and is impaired in aerial mycelium formation. This suggests that RmdA and RmdB functions are additive and at least partially overlapping. The rmdA and rmdB mutations likely result in increased local pools of intracellular c-di-GMP, because intracellular c-di-GMP levels in the single mutants did not differ significantly from those of the wild type, whereas in the double rmdA rmdB mutant, c-di-GMP levels were 3-fold higher than those in the wild type. This study highlights the importance of c-di-GMP-dependent signaling in actinomycete colony morphology and development and identifies two c-di-GMP phosphodiesterases controlling these processes.
authors: Department of Biology, Juniata College, Huntingdon, Pennsylvania, USA.
authors: Travis D
authors: TD
authors: Hull
authors: Min-Hyung
authors: MH
authors: Ryu
authors: Matthew J
authors: MJ
authors: Sullivan
authors: Ryan C
authors: RC
authors: Johnson
authors: Nikolai T
authors: NT
authors: Klena
authors: Robert M
authors: RM
authors: Geiger
authors: Mark
authors: M
authors: Gomelsky
authors: Jennifer A
authors: JA
authors: Bennett
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D004251:DNA Transposable Elements; D015964:Gene Expression Regulation, Bacterial; D009154:Mutation; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism*; D013171:Spores, Bacterial / Q000235:genetics / Q000378:metabolism; D048372:Streptomyces coelicolor / Q000166:cytology / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D004251:DNA Transposable Elements; C062025:bis(3',5')-cyclic diguanylic acid; D010727:Phosphoric Diester Hydrolases; D006152:Cyclic GMP