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Layered Structure and Complex Mechanochemistry Underlie Strength and Versatility in a Bacterial Adhesive
Mercedes Hernando-Pérez1, Sima Setayeshgar2, Yifeng Hou3
1Department of Chemistry, Indiana University, Bloomington, Indiana, USA.
Mbio
|February 14, 2018
Summary
The bacterium Caulobacter crescentus uses a complex, layered bioadhesive called the holdfast for strong underwater attachment. This adhesive contains polysaccharides, peptides, and DNA, contributing to its versatile wet adhesion properties.
Area of Science:
- Microbiology and Biomaterials Science
- Investigating bacterial adhesion mechanisms and bioadhesive properties.
Background:
- Designing synthetic adhesives for aqueous environments is challenging.
- Microorganisms produce effective bioadhesives, like the holdfast from Caulobacter crescentus, for wet surface attachment.
Purpose of the Study:
- To elucidate the complex structure and chemical composition of the Caulobacter crescentus holdfast.
- To characterize the role of its constituents in adhesion and mechanochemistry.
Main Methods:
- Utilized atomic force microscopy and superresolution microscopy.
- Performed enzymatic assays to analyze chemical constituents.
- Investigated the elastic response of the holdfast post-surface contact.
Main Results:
- The holdfast is a two-layered material: a stiff nanoscopic core and a flexible brush layer.
- Holdfast composition includes N-acetyl-d-glucosamine (NAG), peptides, and DNA.
- Elastic response transitions from heterogeneous to homogeneous after surface contact.
Conclusions:
- Holdfast's layered structure and diverse composition (polysaccharides, peptides, DNA) enable strong wet adhesion.
- Peptides likely contribute most to adhesive force, DNA to the brush layer and initial adhesion, and NAG to core structure.
- Understanding this bioadhesive's mechanochemistry can inform the development of novel underwater adhesives.
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