Layered Structure and Complex Mechanochemistry Underlie Strength and Versatility in a Bacterial Adhesive

ABSTRACT While designing synthetic adhesives that perform in aqueous environments has proven challenging, microorganisms commonly produce bioadhesives that efficiently attach to a variety of substrates, including wet surfaces. The aquatic bacterium Caulobacter crescentus uses a discrete polysacchari...

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Autores principales: Mercedes Hernando-Pérez, Sima Setayeshgar, Yifeng Hou, Roger Temam, Yves V. Brun, Bogdan Dragnea, Cécile Berne
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Publicado: American Society for Microbiology 2018
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spelling oai:doaj.org-article:a5248ecc11a645ebb6e86f8525517de62021-11-15T15:53:26ZLayered Structure and Complex Mechanochemistry Underlie Strength and Versatility in a Bacterial Adhesive10.1128/mBio.02359-172150-7511https://doaj.org/article/a5248ecc11a645ebb6e86f8525517de62018-03-01T00:00:00Zhttps://journals.asm.org/doi/10.1128/mBio.02359-17https://doaj.org/toc/2150-7511ABSTRACT While designing synthetic adhesives that perform in aqueous environments has proven challenging, microorganisms commonly produce bioadhesives that efficiently attach to a variety of substrates, including wet surfaces. The aquatic bacterium Caulobacter crescentus uses a discrete polysaccharide complex, the holdfast, to strongly attach to surfaces and resist flow. The holdfast is extremely versatile and has impressive adhesive strength. Here, we used atomic force microscopy in conjunction with superresolution microscopy and enzymatic assays to unravel the complex structure of the holdfast and to characterize its chemical constituents and their role in adhesion. Our data support a model whereby the holdfast is a heterogeneous material organized as two layers: a stiffer nanoscopic core layer wrapped into a sparse, far-reaching, flexible brush layer. Moreover, we found that the elastic response of the holdfast evolves after surface contact from initially heterogeneous to more homogeneous. From a composition point of view, besides N-acetyl-d-glucosamine (NAG), the only component that had been identified to date, our data show that the holdfast contains peptides and DNA. We hypothesize that, while polypeptides are the most important components for adhesive force, the presence of DNA mainly impacts the brush layer and the strength of initial adhesion, with NAG playing a primarily structural role within the core. The unanticipated complexity of both the structure and composition of the holdfast likely underlies its versatility as a wet adhesive and its distinctive strength. Continued improvements in understanding of the mechanochemistry of this bioadhesive could provide new insights into how bacteria attach to surfaces and could inform the development of new adhesives. IMPORTANCE There is an urgent need for strong, biocompatible bioadhesives that perform underwater. To strongly adhere to surfaces and resist flow underwater, the bacterium Caulobacter crescentus produces an adhesive called the holdfast, the mechanochemistry of which remains undefined. We show that the holdfast is a layered structure with a stiff core layer and a polymeric brush layer and consists of polysaccharides, polypeptides, and DNA. The DNA appears to play a role in the structure of the brush layer and initial adhesion, the peptides in adhesive strength, and the polysaccharides in the structure of the core. The complex, multilayer organization and diverse chemistry described here underlie the distinctive adhesive properties of the holdfast and will provide important insights into the mechanisms of bacterial adhesion and bioadhesive applications.Mercedes Hernando-PérezSima SetayeshgarYifeng HouRoger TemamYves V. BrunBogdan DragneaCécile BerneAmerican Society for Microbiologyarticleatomic force microscopybacterial adhesionbioadhesiveCaulobacter crescentusholdfastMicrobiologyQR1-502ENmBio, Vol 9, Iss 1 (2018)
institution DOAJ
collection DOAJ
language EN
topic atomic force microscopy
bacterial adhesion
bioadhesive
Caulobacter crescentus
holdfast
Microbiology
QR1-502
spellingShingle atomic force microscopy
bacterial adhesion
bioadhesive
Caulobacter crescentus
holdfast
Microbiology
QR1-502
Mercedes Hernando-Pérez
Sima Setayeshgar
Yifeng Hou
Roger Temam
Yves V. Brun
Bogdan Dragnea
Cécile Berne
Layered Structure and Complex Mechanochemistry Underlie Strength and Versatility in a Bacterial Adhesive
description ABSTRACT While designing synthetic adhesives that perform in aqueous environments has proven challenging, microorganisms commonly produce bioadhesives that efficiently attach to a variety of substrates, including wet surfaces. The aquatic bacterium Caulobacter crescentus uses a discrete polysaccharide complex, the holdfast, to strongly attach to surfaces and resist flow. The holdfast is extremely versatile and has impressive adhesive strength. Here, we used atomic force microscopy in conjunction with superresolution microscopy and enzymatic assays to unravel the complex structure of the holdfast and to characterize its chemical constituents and their role in adhesion. Our data support a model whereby the holdfast is a heterogeneous material organized as two layers: a stiffer nanoscopic core layer wrapped into a sparse, far-reaching, flexible brush layer. Moreover, we found that the elastic response of the holdfast evolves after surface contact from initially heterogeneous to more homogeneous. From a composition point of view, besides N-acetyl-d-glucosamine (NAG), the only component that had been identified to date, our data show that the holdfast contains peptides and DNA. We hypothesize that, while polypeptides are the most important components for adhesive force, the presence of DNA mainly impacts the brush layer and the strength of initial adhesion, with NAG playing a primarily structural role within the core. The unanticipated complexity of both the structure and composition of the holdfast likely underlies its versatility as a wet adhesive and its distinctive strength. Continued improvements in understanding of the mechanochemistry of this bioadhesive could provide new insights into how bacteria attach to surfaces and could inform the development of new adhesives. IMPORTANCE There is an urgent need for strong, biocompatible bioadhesives that perform underwater. To strongly adhere to surfaces and resist flow underwater, the bacterium Caulobacter crescentus produces an adhesive called the holdfast, the mechanochemistry of which remains undefined. We show that the holdfast is a layered structure with a stiff core layer and a polymeric brush layer and consists of polysaccharides, polypeptides, and DNA. The DNA appears to play a role in the structure of the brush layer and initial adhesion, the peptides in adhesive strength, and the polysaccharides in the structure of the core. The complex, multilayer organization and diverse chemistry described here underlie the distinctive adhesive properties of the holdfast and will provide important insights into the mechanisms of bacterial adhesion and bioadhesive applications.
format article
author Mercedes Hernando-Pérez
Sima Setayeshgar
Yifeng Hou
Roger Temam
Yves V. Brun
Bogdan Dragnea
Cécile Berne
author_facet Mercedes Hernando-Pérez
Sima Setayeshgar
Yifeng Hou
Roger Temam
Yves V. Brun
Bogdan Dragnea
Cécile Berne
author_sort Mercedes Hernando-Pérez
title Layered Structure and Complex Mechanochemistry Underlie Strength and Versatility in a Bacterial Adhesive
title_short Layered Structure and Complex Mechanochemistry Underlie Strength and Versatility in a Bacterial Adhesive
title_full Layered Structure and Complex Mechanochemistry Underlie Strength and Versatility in a Bacterial Adhesive
title_fullStr Layered Structure and Complex Mechanochemistry Underlie Strength and Versatility in a Bacterial Adhesive
title_full_unstemmed Layered Structure and Complex Mechanochemistry Underlie Strength and Versatility in a Bacterial Adhesive
title_sort layered structure and complex mechanochemistry underlie strength and versatility in a bacterial adhesive
publisher American Society for Microbiology
publishDate 2018
url https://doaj.org/article/a5248ecc11a645ebb6e86f8525517de6
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AT yifenghou layeredstructureandcomplexmechanochemistryunderliestrengthandversatilityinabacterialadhesive
AT rogertemam layeredstructureandcomplexmechanochemistryunderliestrengthandversatilityinabacterialadhesive
AT yvesvbrun layeredstructureandcomplexmechanochemistryunderliestrengthandversatilityinabacterialadhesive
AT bogdandragnea layeredstructureandcomplexmechanochemistryunderliestrengthandversatilityinabacterialadhesive
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