title: Visco-elastic membrane tethers extracted from Escherichia coli by optical tweezers.
abstract: Tethers were created between a living Escherichia coli bacterium and a bead by unspecifically attaching the bead to the outer membrane and pulling it away using optical tweezers. Upon release, the bead returned to the bacterium, thus showing the existence of an elastic tether between the bead and the bacterium. These tethers can be tens of microns long, several times the bacterial length. Using mutants expressing different parts of the outer membrane structure, we have shown that an intact core lipopolysaccharide is a necessary condition for tether formation, regardless of whether the beads were uncoated polystyrene or beads coated with lectin. A physical characterization of the tethers has been performed yielding visco-elastic tether force-extension relationships: for first pull tethers, a spring constant of 10-12 pN/mum describes the tether visco-elasticity, for subsequent pulls the spring constant decreases to 6-7 pN/mum, and typical relaxation timescales of hundreds of seconds are observed. Studies of tether stability in the presence of proteases, lipases, and amylases lead us to propose that the extracted tether is primarily composed of the asymmetric lipopolysaccharide containing bilayer of the outer membrane. This unspecific tethered attachment mechanism could be important in the initiation of bacterial adhesion.
authors: The Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.
authors: Liselotte
authors: L
authors: Jauffred
authors: Thomas Hønger
authors: TH
authors: Callisen
authors: Lene Broeng
authors: LB
authors: Oddershede
mesh_terms: D001422:Bacterial Adhesion / Q000502:physiology*; D022081:Cell Surface Extensions / Q000737:chemistry* / Q000502:physiology*; D004548:Elasticity; D004926:Escherichia coli / Q000737:chemistry* / Q000502:physiology*; D052898:Optical Tweezers; D014783:Viscosity
references: J Bacteriol. 1999 Nov;181(22):6865-75
references: 10559150
references: Proc Natl Acad Sci U S A. 2007 Apr 3;104(14):5830-5
references: 17389398
references: Biophys J. 2002 Mar;82(3):1386-95
references: 11867454
references: Biophys J. 2002 Jun;82(6):2964-9
references: 12023219
references: Biophys J. 2002 Dec;83(6):3152-61
references: 12496085
references: Ann Biomed Eng. 2002 Nov-Dec;30(10):1273-80
references: 12540203
references: Biophys J. 1996 Jan;70(1):358-69
references: 8770212
references: Biophys J. 1996 Sep;71(3):1374-88
references: 8874013
references: Nat Biotechnol. 1997 Mar;15(3):269-72
references: 9062928
references: Biophys J. 1997 Jun;72(6):2669-78
references: 9168042
references: Eur Biophys J. 1998;27(3):197-209
references: 9615393
references: Biophys J. 1999 Apr;76(4):2056-71
references: 10096901
references: Biophys J. 1999 Oct;77(4):1992-2002
references: 10512819
references: Biophys J. 2004 Dec;87(6):4271-83
references: 15377509
references: J Bacteriol. 2005 Mar;187(5):1710-5
references: 15716442
references: Biophys J. 2005 Mar;88(3):2288-98
references: 15653718
references: Biophys J. 2005 Mar;88(3):2299-308
references: 15653735
references: Phys Rev Lett. 2005 Feb 18;94(6):068101
references: 15783778
references: Biophys J. 2005 Apr;88(4):2714-26
references: 15695629
references: Biophys J. 1999 Dec;77(6):3363-70
references: 10585959