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Atomic force microscopy study of the role of LPS O‐antigen on adhesion of E. coli
Author(s) -
Strauss Joshua,
Burnham Nancy A.,
Camesano Terri A.
Publication year - 2009
Publication title -
journal of molecular recognition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.401
H-Index - 79
eISSN - 1099-1352
pISSN - 0952-3499
DOI - 10.1002/jmr.955
Subject(s) - escherichia coli , lipopolysaccharide , antigen , adhesion , silicon nitride , bacterial outer membrane , chemistry , virulence , bacterial cell structure , atomic force microscopy , bacteria , microbiology and biotechnology , strain (injury) , enterobacteriaceae , biophysics , crystallography , biology , silicon , materials science , nanotechnology , biochemistry , immunology , genetics , organic chemistry , gene , anatomy
The O‐antigen is a highly variable component of the lipopolysaccharide (LPS) among Escherichia coli strains and is useful for strain identification and assessing virulence. While the O‐antigen has been chemically well characterized in terms of sugar composition, physical properties such as O‐antigen length of E. coli LPS have not been well studied, even though LPS length is important for determining binding of bacteria to biomolecules and epithelial cells. Atomic force microscopy (AFM) was used to characterize the physicochemical properties of the LPS of eight E. coli strains. Steric repulsion between the AFM tip (silicon nitride) and the E. coli cells was measured and modeled, to determine LPS lengths for three O157 and two O113 E. coli strains, and three control (K12) strains that do not express the O‐antigen. For strains with an O‐antigen, the LPS lengths ranged from 17 ± 10 to 37 ± 9 nm, and LPS length was positively correlated with the force of adhesion ( F adh ). Longer lengths of LPS may have allowed for more hydrogen bonding between the O‐antigen and silanol groups of the AFM silicon nitride tip, which controlled the magnitude of F adh . For control strains, LPS lengths ranged from 3 ± 2 to 5 ± 3 nm, and there was no relationship between LPS length and adhesion force between the bacterium and the silicon nitride tip. In the absence of the O‐antigen, we attributed F adh to electrostatic interactions with lipids in the bacterial membrane. Copyright © 2009 John Wiley & Sons, Ltd.