Optical tweezers based force measurement system for quantitating binding interactions: system design and application for the study of bacterial adhesion

Fällman, Erik; Schedin, Staffan; Jaß, Jana; Andersson, Magnus; Uhlin, Bernt Eric; Axner, Ove

doi:10.1016/j.bios.2003.12.029

Cited by 110 publications

(81 citation statements)

References 20 publications

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“…Force spectroscopy was performed using an optical tweezers (OT) setup as previously described (40,41). Briefly, probe beads and bacterial cells were trapped with an Nd:YVO 4 (1,064 nm) laser in continuous-wave mode.…”

Section: Methodsmentioning

confidence: 99%

Antibodies Damage the Resilience of Fimbriae, Causing Them To Be Stiff and Tangled

et al. 2017

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As adhesion fimbriae are a major virulence factor for many pathogenic Gram-negative bacteria, they are also potential targets for antibodies. Fimbriae are commonly required for initiating the colonization that leads to disease, and their success as adhesion organelles lies in their ability to both initiate and sustain bacterial attachment to epithelial cells. The ability of fimbriae to unwind and rewind their helical filaments presumably reduces their detachment from tissue surfaces with the shear forces that accompany significant fluid flow. Therefore, the disruption of functional fimbriae by inhibiting this resilience should have high potential for use as a vaccine to prevent disease. In this study, we show that two characteristic biomechanical features of fimbrial resilience, namely, the extension force and the extension length, are significantly altered by the binding of antibodies to fimbriae. The fimbriae that were studied are normally expressed on enterotoxigenic Escherichia coli, which are a major cause of diarrheal disease. This alteration in biomechanical properties was observed with bivalent polyclonal antifimbrial antibodies that recognize major pilin subunits but not with the Fab fragments of these antibodies. Thus, we propose that the mechanism by which bound antibodies disrupt the uncoiling of natural fimbria under force is by clamping together layers of the helical filament, thereby increasing their stiffness and reducing their resilience during fluid flow. In addition, we propose that antibodies tangle fimbriae via bivalent binding, i.e., by binding to two individual fimbriae and linking them together. Use of antibodies to disrupt physical properties of fimbriae may be generally applicable to the large number of Gram-negative bacteria that rely on these surface-adhesion molecules as an essential virulence factor. IMPORTANCE Our study shows that the resiliency of colonization factor antigen I (CFA/I) and coli surface antigen 2 (CS2) fimbriae, which are current targets for vaccine development, can be compromised significantly in the presence of antifimbrial antibodies. It is unclear how the humoral immune system specifically interrupts infection after the attachment of enterotoxigenic Escherichia coli (ETEC) to the epithelial surface. Our study indicates that immunoglobulins, in addition to their welldocumented role in adaptive immunity, can mechanically damage the resilience of fimbriae of surface-attached ETEC, thereby revealing a new mode of action. Our data suggest a mechanism whereby antibodies coat adherent and free-floating bacteria to impede fimbrial resilience. Further elucidation of this possible mechanism is likely to inform the development and refinement of preventive vaccines against ETEC diarrhea.KEYWORDS pili, IgG, vaccine, CFA/I, CS2, optical tweezers

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Section: Methodsmentioning

confidence: 99%

Antibodies Damage the Resilience of Fimbriae, Causing Them To Be Stiff and Tangled

et al. 2017

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“…argonion laser-pumped continuous-wave titanium-sapphire laser, operating at a wavelength of 810 nm, is used for optical trapping. A complete description of the optical system for controlling the laser beam that forms the optical trap and modifications made to the microscope to realize the OT system is reported in Fällman and Axner (1997) and Fällman et al (2004). The displacement of a small bead held in the optical trap constitutes a measure of the force that is exerted on the bead.…”

Section: Methodsmentioning

confidence: 99%

Helicobacter pylori Adhesion to Carbohydrates

Aspholm¹,

Kalia²,

Rühl³

et al. 2006

Methods in Enzymology

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Adherence of bacterial pathogens to host tissues contributes to colonization and virulence and typically involves specific interactions between bacterial proteins called adhesins and cognate oligosaccharide (glycan) or protein motifs in the host that are used as receptors. A given pathogen may have multiple adhesins, each specific for a different set of receptors and, potentially, with different roles in infection and disease. This chapter provides strategies for identifying and analyzing host glycan receptors and the bacterial adhesins that exploit them as receptors, with particular reference to adherence of the gastric pathogen Helicobacter pylori.

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“…We built our setup around an Olympus IX71 microscope, normally used for optical tweezers force spectroscopy and flow chamber assays, which was modified to illuminate samples according to an in--line holography setup using a collimated low--cost LED operating at 470 nm (M470L3--C1, Thorlabs) [13]. The LED was collimated using a free space collimator consisting of a microscope objective (Plan N 10x/0.25, Olympus) mounted on a fiber holder (MBT613, Thorlabs).…”

Section: Experimental Procedures and Theorymentioning

confidence: 99%

Cell shape identification using digital holographic microscopy

2015

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We present a cost--effective, simple and fast digital holographic microscopy method based upon Rayleigh--Sommerfeld back propagation for identification of the geometrical shape of a cell. The method was tested using synthetic hologram images generated by ray--tracing software and from experimental images of semi--transparent spherical beads and living red blood cells. Our results show that by only using the real part of the back--reconstructed amplitude the proposed method can provide information of the geometrical shape of the object and at the same time accurately determine the axial position of the object under study. The proposed method can be used in flow chamber assays for pathophysiological studies where fast morphological changes of cells are studied in high numbers and at different heights.

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Optical tweezers based force measurement system for quantitating binding interactions: system design and application for the study of bacterial adhesion

Cited by 110 publications

References 20 publications

Antibodies Damage the Resilience of Fimbriae, Causing Them To Be Stiff and Tangled

Antibodies Damage the Resilience of Fimbriae, Causing Them To Be Stiff and Tangled

Helicobacter pylori Adhesion to Carbohydrates

Cell shape identification using digital holographic microscopy

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