title: Visualizing the perturbation of cellular cyclic di-GMP levels in bacterial cells.
abstract: Cyclic di-GMP (c-di-GMP) has emerged as a prominent intracellular messenger that coordinates biofilm formation and pathogenicity in many bacterial species. Developing genetically encoded biosensors for c-di-GMP will help us understand how bacterial cells respond to environmental changes via the modulation of cellular c-di-GMP levels. Here we report the design of two genetically encoded c-di-GMP fluorescent biosensors with complementary dynamic ranges. By using the biosensors, we found that several compounds known to promote biofilm dispersal trigger a decline in c-di-GMP levels in  Escherichia coli  cells. In contrast, cellular c-di-GMP levels were elevated when the bacterial cells were treated with subinhibitory concentrations of biofilm-promoting antibiotics. The biosensors also revealed that  E. coli  cells engulfed by macrophages exhibit lower c-di-GMP levels, most likely as a response to the enormous pressures of survival during phagocytosis.
authors.affiliation: Division of Structural Biology and Biochemistry, School of Biological Sciences, Nanyang Technological University, 60 Nanyang Drive, Singapore 637551.
authors.forename: Chun Loong
authors.initials: CL
authors.lastname: Ho
authors.forename: Kavin Shi Jie
authors.initials: KS
authors.lastname: Chong
authors.forename: Jamila Akosua
authors.initials: JA
authors.lastname: Oppong
authors.forename: Mary Lay Cheng
authors.initials: ML
authors.lastname: Chuah
authors.forename: Suet Mien
authors.initials: SM
authors.lastname: Tan
authors.forename: Zhao-Xun
authors.initials: ZX
authors.lastname: Liang
mesh_terms: D015374:Biosensing Techniques; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli; D029968:Escherichia coli Proteins / Q000737:chemistry / Q000235:genetics; D005456:Fluorescent Dyes / Q000737:chemistry; D015394:Molecular Structure
chemical_list: C559839:BdcA protein, E coli; D029968:Escherichia coli Proteins; D005456:Fluorescent Dyes; C062025:bis(3',5')-cyclic diguanylic acid; D006152:Cyclic GMP