Visco-elastic membrane tethers extracted from Escherichia coli by optical tweezers.
Biophys J
; 93(11): 4068-75, 2007 Dec 01.
Article
em En
| MEDLINE
| ID: mdl-17704145
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.
Texto completo:
1
Base de dados:
MEDLINE
Assunto principal:
Aderência Bacteriana
/
Extensões da Superfície Celular
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Escherichia coli
Idioma:
En
Ano de publicação:
2007
Tipo de documento:
Article