Role of Cyclic Di-GMP and Exopolysaccharide in Type IV Pilus Dynamics.
ForPseudomonas aeruginosa, levels of cyclic di-GMP (c-di-GMP) govern the transition from the planktonic state to biofilm formation. Type IV pili (T4P) are crucial determinants of biofilm structure and dynamics, but it is unknown how levels of c-di-GMP affect pilus dynamics. Here, we scrutinized how c-di-GMP affects molecular motor properties and adhesive behavior of T4P. By means of retraction, T4P generated forces of ∼30 pN. Deletion mutants in the proteins with known roles in biofilm formation, swarming motility, and exopolysaccharide (EPS) production (specifically, the diguanylate cyclasessadCandroeAor the c-di-GMP phosphodiesterasebifA) showed only modest effects on velocity or force of T4P retraction. At high levels of c-di-GMP, the production of exopolysaccharides, particularly of Pel, is upregulated. We found that Pel production strongly enhances T4P-mediated surface adhesion ofP. aeruginosa, suggesting that T4P-matrix interactions may be involved in biofilm formation byP. aeruginosaFinally, our data support the previously proposed model of slingshot-like "twitching" motility ofP. aeruginosaIMPORTANCEType IV pili (T4P) play various important roles in the transition of bacteria from the planktonic state to the biofilm state, including surface attachment and surface sensing. Here, we investigate adhesion, dynamics, and force generation of T4P after bacteria engage a surface. Our studies showed that two critical components of biofilm formation byPseudomonas aeruginosa, T4P and exopolysaccharides, contribute to enhanced T4P-mediated force generation by attached bacteria. These data indicate a crucial role for the coordinated impact of multiple biofilm-promoting factors during the early stages of attachment to a surface. Our data are also consistent with a previous model explaining why pilus-mediated motility inP. aeruginosaresults in characteristic "twitching" behavior.
Department of Physics, University of Cologne, Cologne, Germany.
Jan
J
Ribbe
Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA.
Amy E
AE
Baker
Department of Physics, University of Cologne, Cologne, Germany.
Sebastian
S
Euler
Geisel School of Medicine at Dartmouth, Hanover, New Hampshire, USA.
George A
GA
O'Toole
Department of Physics, University of Cologne, Cologne, Germany berenike.maier@uni-koeln.de.
Berenike
B
Maier
D058947:Bacterial Secretion Systems; D006152:Cyclic GMP / Q000031:analogs & derivatives* / Q000235:genetics / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism; D010861:Fimbriae, Bacterial / Q000145:classification* / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D015971:Gene Expression Regulation, Enzymologic; D009068:Movement; D010100:Oxygen / Q000378:metabolism; D010727:Phosphoric Diester Hydrolases / Q000235:genetics / Q000378:metabolism; D019761:Phosphorus-Oxygen Lyases / Q000145:classification / Q000235:genetics / Q000378:metabolism; D011135:Polysaccharides, Bacterial / Q000235:genetics / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000235:genetics / Q000378:metabolism*
D058947:Bacterial Secretion Systems; D029968:Escherichia coli Proteins; D011135:Polysaccharides, Bacterial; C064841:exopolysaccharide, Pseudomonas; C062025:bis(3',5')-cyclic diguanylic acid; D010727:Phosphoric Diester Hydrolases; D019761:Phosphorus-Oxygen Lyases; C060720:diguanylate cyclase; D006152:Cyclic GMP; D010100:Oxygen
Pseudomonas aeruginosa; biofilm; cyclic di-GMP; exopolysaccharide; molecular motor; pili