title: Nanomechanical properties of glucans and associated cell-surface adhesion of Streptococcus mutans probed by atomic force microscopy under in situ conditions.
abstract: This study used atomic force microscopy (AFM) to probe the local cell-surface interactions associated with the glucan polymers of Streptococcus mutans, the macromolecules most commonly attributed to the virulence of this microbe. In situ force spectroscopy was used to quantitatively probe and correlate cell-surface adhesion and dynamics with S. mutans UA140 wild-type and five glucosyltransferase mutants. Adhesion between the tooth surface and S. mutans is largely mediated by glucan production from sucrose via three glucosyltransferases (Gtfs; GtfB, GtfC and GtfD). To monitor the contribution of these particular Gtfs, isogenic mutants of S. mutans were constructed by specific gene inactivation and compared to the wild-type under sucrose and non-sucrose conditions. We report direct measurement of the mechanical properties associated with glucan macromolecules demonstrating that the local adhesion strength increases in a time-dependent process, with a decrease in the average number of rupture events. This finding suggests that S. mutans attaches mainly through glucans to surfaces in the presence of sucrose. In addition, a possible role of the Gtf proteins in sucrose-independent attachment is supported by the decreased adhesion properties of the GtfBCD mutant compared to the wild-type.
authors.affiliation: UCLA Institute for Cell Mimetic Space Exploration, Los Angeles, CA 90095, USA.|UCLA Department of Chemistry and Biochemistry, Los Angeles, CA 90095, USA.
authors.forename: Sarah E
authors.initials: SE
authors.lastname: Cross
authors.affiliation: UCLA School of Dentistry, Los Angeles, CA 90095, USA.
authors.forename: Jens
authors.initials: J
authors.lastname: Kreth
authors.affiliation: UCLA School of Dentistry, Los Angeles, CA 90095, USA.
authors.forename: Lin
authors.initials: L
authors.lastname: Zhu
authors.affiliation: Colgate-Palmolive, Piscataway, NJ 08855, USA.
authors.forename: Richard
authors.initials: R
authors.lastname: Sullivan
authors.affiliation: UCLA Molecular Biology Institute, Los Angeles, CA 90095, USA.|UCLA School of Dentistry, Los Angeles, CA 90095, USA.
authors.forename: Wenyuan
authors.initials: W
authors.lastname: Shi
authors.affiliation: UCLA School of Dentistry, Los Angeles, CA 90095, USA.
authors.forename: Fengxia
authors.initials: F
authors.lastname: Qi
authors.affiliation: UCLA Institute for Cell Mimetic Space Exploration, Los Angeles, CA 90095, USA.|UCLA Department of Chemistry and Biochemistry, Los Angeles, CA 90095, USA.
authors.forename: James K
authors.initials: JK
authors.lastname: Gimzewski
mesh_terms: D001422:Bacterial Adhesion / Q000502:physiology*; D005936:Glucans / Q000096:biosynthesis / Q000737:chemistry* / Q000502:physiology; D005964:Glucosyltransferases / Q000235:genetics / Q000378:metabolism; D018625:Microscopy, Atomic Force / Q000295:instrumentation / Q000379:methods*; D009154:Mutation; D036103:Nanotechnology / Q000295:instrumentation / Q000379:methods*; D013295:Streptococcus mutans / Q000235:genetics / Q000254:growth & development / Q000502:physiology* / Q000648:ultrastructure; D013395:Sucrose / Q000378:metabolism
chemical_list: D005936:Glucans; D013395:Sucrose; D005964:Glucosyltransferases