Characterization of Curli A Production on Living Bacterial Surfaces by Scanning Probe Microscopy

Oh, Yoo Jin; Cui, Yukun; Li, Yinhua; Hinterdorfer, Peter; Park, Sungsu

doi:10.1016/j.bpj.2012.09.004

Cited by 22 publications

(22 citation statements)

References 32 publications

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“…Our results showed that OmpR and CsgD do affect the mechanical properties of the cells outer surface; the much lower E and P0 of expressing curli (E. coli PHL 628 and E. coli MG1655 pT7-7CsgD) is probably the result of the increased need to excrete the curli subunits CsgA and CsgB or through the role of CsgD in the regulation of cellulose production 12,47,48 . The values of Young modulus (E) for E. coli MG1655 obtained in this work ( Figure 5) were similar to those presented by Oh et al 49 and Chen et al 50 for other strains of E. coli. In general, surface distribution of E is assumed to follow a Gaussian profile 35 , whilst not normal distribution for adhesion force and curli geometrical parameters have been reported 40,41 .…”

Section: Discussionsupporting

confidence: 90%

Influence of csgD and ompR on Nanomechanics, Adhesion Forces, and Curli Properties of E. coli

et al. 2016

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Curli are bacterial appendages involved in the adhesion of cells to surfaces; their synthesis is regulated by many genes such as csgD and ompR. The expression of the two curli subunits (CsgA and CsgB) in Escherichia coli (E. coli) is regulated by CsgD; at the same time, csgD transcription is under the control of OmpR. Therefore, both genes are involved in the control of curli production. In this work, we elucidated the role of these genes in the nanomechanical and adhesive properties of E. coli MG1655 (a laboratory strain not expressing significant amount of curli) and its curli-producing mutants overexpressing OmpR and CsgD, employing atomic force microscopy (AFM). Nanomechanical analysis revealed that the expression of these genes gave origin to cells with a lower Young's modulus (E) and turgidity (P0), whereas the adhesion forces were unaffected when genes involved in curli formation were expressed. AFM was also employed to study the primary structure of the curli expressed through the freely jointed chain (FJC) model for polymers. CsgD increased the number of curli on the surface more than OmpR did, and the overexpression of both genes did not result in a greater number of curli. Neither of the genes had an impact on the structure (total length of the polymer and number and length of Kuhn segments) of the curli. Our results further suggest that, despite the widely assumed role of curli in cell adhesion, cell adhesion force is also dictated by surface properties because no relation between the number of curli expressed on the surface and cell adhesion was found.

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Section: Discussionsupporting

confidence: 90%

Influence of csgD and ompR on Nanomechanics, Adhesion Forces, and Curli Properties of E. coli

et al. 2016

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“…Curli fiber equilibrium lengths on E. coli were reported to be 137-373 nm. 17 The equilibrium length of proteinaceous fimbriae on E. coli ranged from 125-272 nm. 26 -comparable to the values measured for the wild-type strain of P. fluorescens, and the lapA and lapB mutants (∼120 nm).…”

Section: Polymer Conformation On the Surface Of P Fluorescensmentioning

confidence: 99%

“…Steric models of the form developed by Alexander-de Gennes (A-dG model) have been used to characterize molecules on bacterial surfaces including lipopolysaccharides (LPS), extracellular polymeric substances, and surface polymers. [16][17][18] Therefore, the objective of this study was to apply the steric model to AFM data, and characterize the physical characteristics of the LapA protein of P. fluorescens.…”

Section: Introductionmentioning

confidence: 99%

Probing Large Protein Adhesin Molecules on <I>Pseudomonas fluorescens</I> with Atomic Force Microscopy

Schwartz¹,

Ivanov²,

Boyd³

et al. 2014

j bionanosci

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Protein adhesins are an important type of surface structure, and are components of some Gramnegative bacterial outer membranes, such as Pseudomonas fluorescens. The LapA adhesin is a major surface protein on this bacterium, which is required for irreversible adhesion and the initiation of biofilm formation. Atomic force microscopy (AFM) was used to characterize surface structures of P. fluorescens Pf0-1. The wild-type and three genetically modified strains were studied, namely a strain consisting of a single cross-over knockout mutation disrupting the lapA gene, a strain consisting of a single cross-over knockout mutation disrupting the lapB gene, (LapA is maintained in the cytoplasm and not transported to the cell surface), and a lapG deletion mutant (LapA is unable to be cleaved from the cell surface). AFM data was modeled using the Alexander-de Gennes (A-dG) relation for steric repulsion. We calculated the equilibrium layer thickness of the surface structures as well as spacing between adhesins. The wild-type strain and the lapA and lapB mutants all showed similar spacing for surface proteins. The strain lacking LapG had the smallest spacing between molecules. This suggests that the absence of the LapG protease allowed the LapA protein to accumulate, thus decreasing the overall molecular spacing of the protein on the bacterial surface compared to the wild-type strain. We found that the lapG mutant strain of P. fluorescens behaved like a classical polymer brush, in which the spacing between molecules was very small (3.3 nm), which would allow intermolecular interactions between protein units. Recent work has shown that the lapG mutant has greater adhesion and biofilm formation than the wild-type, lapA, and lapB strains, and exhibits stiffer conformation of LapA due to higher protein density and aggregation. Taken together, our results and these recent studies support the finding that LapA adhesin conformation is related to irreversible bacterial adhesion.

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“…Studies with varying curli production indicate that the fibers are critical for strong adhesion ( 34 , 45 ), and increased curli expression has been shown to result in pellicles with increased surface elasticity and strength ( 43 ). Curli overproduction has been shown to substantially increase adhesion, and attachment strength has been noted to vary by surface type: the strongest interactions were seen for hydrophobic plastics, relative to hydrophilic metals or glass ( 45 , 46 ). Still, the fundamental mechanisms that allow curliated biofilms to achieve this outstanding adhesion are yet unknown.…”

Section: Introductionmentioning

confidence: 99%

Adhesion mechanisms of curli subunit CsgA to abiotic surfaces

2016

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Characterization of Curli A Production on Living Bacterial Surfaces by Scanning Probe Microscopy

Cited by 22 publications

References 32 publications

Influence of csgD and ompR on Nanomechanics, Adhesion Forces, and Curli Properties of E. coli

Influence of csgD and ompR on Nanomechanics, Adhesion Forces, and Curli Properties of E. coli

Probing Large Protein Adhesin Molecules on <I>Pseudomonas fluorescens</I> with Atomic Force Microscopy

Adhesion mechanisms of curli subunit CsgA to abiotic surfaces

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