title: The Pseudomonas aeruginosa diguanylate cyclase GcbA, a homolog of P. fluorescens GcbA, promotes initial attachment to surfaces, but not biofilm formation, via regulation of motility.
abstract: Cyclic di-GMP is a conserved signaling molecule regulating the transitions between motile and sessile modes of growth in a variety of bacterial species. Recent evidence suggests that Pseudomonas species harbor separate intracellular pools of c-di-GMP to control different phenotypic outputs associated with motility, attachment, and biofilm formation, with multiple diguanylate cyclases (DGCs) playing distinct roles in these processes, yet little is known about the potential conservation of functional DGCs across Pseudomonas species. In the present study, we demonstrate that the P. aeruginosa homolog of the P. fluorescens DGC GcbA involved in promoting biofilm formation via regulation of swimming motility likewise synthesizes c-di-GMP to regulate surface attachment via modulation of motility, however, without affecting subsequent biofilm formation. P. aeruginosa GcbA was found to regulate flagellum-driven motility by suppressing flagellar reversal rates in a manner independent of viscosity, surface hardness, and polysaccharide production. P. fluorescens GcbA was found to be functional in P. aeruginosa and was capable of restoring phenotypes associated with inactivation of gcbA in P. aeruginosa to wild-type levels. Motility and attachment of a gcbA mutant strain could be restored to wild-type levels via overexpression of the small regulatory RNA RsmZ. Furthermore, epistasis analysis revealed that while both contribute to the regulation of initial surface attachment and flagellum-driven motility, GcbA and the phosphodiesterase DipA act within different signaling networks to regulate these processes. Our findings expand the complexity of c-di-GMP signaling in the regulation of the motile-sessile switch by providing yet another potential link to the Gac/Rsm network and suggesting that distinct c-di-GMP-modulating signaling pathways can regulate a single phenotypic output.
authors.affiliation: Department of Biological Sciences, Binghamton University, Binghamton, New York, USA.
authors.forename: Olga E
authors.initials: OE
authors.lastname: Petrova
authors.affiliation: Department of Biological Sciences, Binghamton University, Binghamton, New York, USA.
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Cherny
authors.affiliation: Department of Biological Sciences, Binghamton University, Binghamton, New York, USA ksauer@binghamton.edu.
authors.forename: Karin
authors.initials: K
authors.lastname: Sauer
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D018441:Biofilms; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics / Q000378:metabolism; D005407:Flagella / Q000378:metabolism; D015964:Gene Expression Regulation, Bacterial; D005816:Genetic Complementation Test; D009068:Movement; D010641:Phenotype; D010727:Phosphoric Diester Hydrolases / Q000378:metabolism; D019761:Phosphorus-Oxygen Lyases / Q000235:genetics / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000378:metabolism; D011137:Polystyrenes; D011401:Promoter Regions, Genetic; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D017384:Sequence Deletion; D015398:Signal Transduction
chemical_list: D001426:Bacterial Proteins; D029968:Escherichia coli Proteins; D011135:Polysaccharides, Bacterial; D011137:Polystyrenes; C062025:bis(3',5')-cyclic diguanylic acid; D010727:Phosphoric Diester Hydrolases; D019761:Phosphorus-Oxygen Lyases; C060720:diguanylate cyclase; D006152:Cyclic GMP