Contour and persistence length of Corynebacterium diphtheriae pili by atomic force microscopy

Abstract

Many bacteria are characterized by nanoscale ultrastructures, for example S-layers, flagella, fimbriae, or pili. The last two are especially important for attachment to different abiotic and biotic surfaces and for host-pathogen interactions. In this study, we investigated the geometric and elastic properties of pili of different Corynebacterium diphtheriae strains by atomic force microscopy (AFM). We performed quantitative contour-length analysis of bacterial pili and found that the visible contour length of the pili can be described by a log-normal distribution. Our data revealed significant strain-specific variations in the mean visible contour length of the pili, ranging from 260 to 1,590 nm. To estimate their full contour length, which is not directly accessible from the AFM images, we developed a simple correction model. Using this model, we determined the mean full contour length as 510-2,060 nm. To obtain the persistence length we used two different methods of analysis, one based on the end-to-end distance of the pili and one based on the bending angles of short segments. In comparison, the bending angle analysis proved to be more precise and resulted in persistence lengths in the narrow range of 220-280 nm, with no significant strain-specific variations. This is small compared with some other bacterial polymers, for example type IV pili, F-pili, or flagella.

Induction of the NFκ-B signal transduction pathway in response to Corynebacterium diphtheriae infection

“…gravis, non-toxigenic, isolated from patients affected by pharyngitis/tonsillitis, no pili (Ott et al, 2010b;Rheinlaender et al, 2012) Bertuccini et al (2004 ISS4746 C. diphtheriae var. gravis, non-toxigenic, isolated from patients affected by pharyngitis/tonsillitis, medium number of extended pili (Ott et al, 2010b;Rheinlaender et al, 2012) Subsequently, the cells were incubated for 2 h in DMEM (500 ml per well) containing 100 mg gentamicin ml 21 to kill remaining extracellular bacteria. After this incubation, the cell layers were washed three times with PBS, detached by adding 500 ml trypsin solution (0.12 % trypsin, 0.01 % EDTA in PBS) per well (5 min, 37 uC, 5 % CO 2 , 90 % humidity), and lysed for 5 min at 37 uC with 0.025 % Tween 20 to liberate the intracellular bacteria.…”

“…Detroit562 and HeLa cells were seeded in 24-well plates (Nunc) at a density of 1610 5 and 5610 4 cells per well, (Ott et al, 2010b;Rheinlaender et al, 2012) DSMZ, Braunschweig, Germany DSM43989 tox + , unknown source, medium pili length and number (Ott et al, 2010b;Rheinlaender et al, 2012) DSMZ, Braunschweig, Germany DSM44123…”

“…Non-toxigenic isolate, type strain, unknown source, medium number short spike-like pili (Ott et al, 2010b;Rheinlaender et al, 2012) DSMZ, Braunschweig, Germany ISS3319…”

“…diphtheriae var. mitis, non-toxigenic, isolated from patients affected by pharyngitis/tonsillitis, medium pili length and number (Ott et al, 2010b;Rheinlaender et al, 2012) Bertuccini et al…”

Dynamic Modulation of Fimbrial Extension and FimH-Mannose Binding Force on Live Bacteria Under pH Changes: A Molecular Atomic Force Microscopy Analysis

“…When the pulling rate is increased to 20 µm/s ( Figure 3d), a narrower distribution is found with L c values in the range 0.2 µm to 2 µm and a weak distribution in the range of 2 µm to 6 µm, which is in line with literature. 41 In order to further rationalize this dependence of L c on pulling rate as derived from force curve modeling, we report in Figure 4 the pH- and pulling rate-mediated variations of the maximal elongation of type 1 fimbriae prior to the last rupture event detected in the force curves. The reader is referred to Figure S3 for typical force curves data collected at various pH values and 2 µm/s pulling rate, and to Figure S4 for corresponding statistical distribution in maximal elongation length (Table S1).…”