title: LapD is a bis-(3',5')-cyclic dimeric GMP-binding protein that regulates surface attachment by Pseudomonas fluorescens Pf0-1.
abstract: The second messenger cyclic dimeric GMP (c-di-GMP) regulates surface attachment and biofilm formation by many bacteria. For Pseudomonas fluorescens Pf0-1, c-di-GMP impacts the secretion and localization of the adhesin LapA, which is absolutely required for stable surface attachment and biofilm formation by this bacterium. In this study we characterize LapD, a unique c-di-GMP effector protein that controls biofilm formation by communicating intracellular c-di-GMP levels to the membrane-localized attachment machinery via its periplasmic domain. LapD contains degenerate and enzymatically inactive diguanylate cyclase and c-di-GMP phosphodiesterase (EAL) domains and binds to c-di-GMP through a degenerate EAL domain. We present evidence that LapD utilizes an inside-out signaling mechanism: binding c-di-GMP in the cytoplasm and communicating this signal to the periplasm via its periplasmic domain. Furthermore, we show that LapD serves as the c-di-GMP receptor connecting environmental modulation of intracellular c-di-GMP levels by inorganic phosphate to regulation of LapA localization and thus surface commitment by P. fluorescens.
authors.affiliation: Department of Microbiology and Immunology, Dartmouth Medical School, Hanover, NH 03755, USA.
authors.forename: Peter D
authors.initials: PD
authors.lastname: Newell
authors.forename: Russell D
authors.initials: RD
authors.lastname: Monds
authors.forename: George A
authors.initials: GA
authors.lastname: O'Toole
mesh_terms: D015106:3',5'-Cyclic-GMP Phosphodiesterases / Q000378:metabolism; D018829:Adhesins, Bacterial / Q000378:metabolism; D001422:Bacterial Adhesion; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism; D004789:Enzyme Activation; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D055503:Protein Multimerization; D011551:Pseudomonas fluorescens / Q000235:genetics / Q000378:metabolism*; D015398:Signal Transduction
chemical_list: D018829:Adhesins, Bacterial; D002352:Carrier Proteins; D047908:Intracellular Signaling Peptides and Proteins; C022994:cyclic GMP-binding protein; C062025:bis(3',5')-cyclic diguanylic acid; D015106:3',5'-Cyclic-GMP Phosphodiesterases; D006152:Cyclic GMP