Quantitative nanoscale electrostatics of viruses

Hernando-Pérez, Mercedes; Cartagena‐Rivera, Alexander X.; Božič, Lošdorfer; Carrillo, Pablo J. P.; Martín, Carmen San; Mateu, Mauricio G.; Raman, Arvind; Podgornik, Rudolf; Pablo, Pedro

doi:10.1039/c5nr04274g

Cited by 54 publications

(59 citation statements)

References 52 publications

(99 reference statements)

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“…Fixation of protein shells to a flat substrate via hydrophobic 35 and/or electrostatic interactions 36 is a requisite for AFM. Each protein shell has individual features such as hydrophobic patches or local charge densities, resulting in distinct attachment forces.…”

Section: Resultsmentioning

confidence: 99%

Cargo–shell and cargo–cargo couplings govern the mechanics of artificially loaded virus-derived cages

et al. 2016

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Nucleic acids are the natural cargo of viruses and key determinants that affect viral shell stability. In some cases the genome structurally reinforces the shell, whereas in others genome packaging causes internal pressure that can induce destabilization. Although it is possible to pack heterologous cargoes inside virus-derived shells, little is known about the physical determinants of these artificial nanocontainers’ stability. Atomic force and three-dimensional cryo-electron microscopy provided mechanical and structural information about the physical mechanisms of viral cage stabilization beyond the mere presence/absence of cargos. We analyzed the effects of cargo–shell and cargo–cargo interactions on shell stability after encapsulating two types of proteinaceous payloads. While bound cargo to the inner capsid surface mechanically reinforced the capsid in a structural manner, unbound cargo diffusing freely within the shell cavity pressurized the cages up to ~30 atm due to steric effects. Strong cargo–cargo coupling reduces the resilience of these nanocompartments in ~20% when bound to the shell. Understanding the stability of artificially loaded nanocages will help to design more robust and durable molecular nanocontainers.

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Section: Resultsmentioning

confidence: 99%

Cargo–shell and cargo–cargo couplings govern the mechanics of artificially loaded virus-derived cages

et al. 2016

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“…For enzyme-treated holdfasts, 17, 34, and 25 different holdfasts were measured in at least 2 independent replicates for the proteinase K, DNase I, and lysozyme treatments, respectively, yielding collections of 87, 130, and 127 F -versus- Z curves, respectively. To characterize the interactions between the AFM tip and the holdfast, we converted the F -versus- Z curves into force-versus-distance tip-sample curves ( F versus D ; gap distance, D = Z − Z 0 − d ), where Z is the piezo displacement, Z 0 is the point to contact, and d is the average cantilever normal deflection, as routinely performed in AFM spectroscopy for rigid surfaces ( 82 , 83 ) ( Fig. 3 ), using a script developed in-house on the basis of Igor Pro software.…”

Section: Methodsmentioning

confidence: 99%

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

Hernando-Pérez

Setayeshgar

Hou

et al. 2018

mBio

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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.

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“…where Z is the piezo displacement, Z 0 is the point to contact and d is the average cantilever normal deflection, as routinely performed in AFM spectroscopy for rigid surfaces 60,61 (Fig. S1), using a home script based on the Igor Pro software.…”

Section: Dynamic Adhesion Force Spectroscopy Experiments Dynamicmentioning

confidence: 99%

“…We observed approximate linear behavior in the limit of large forces and characterized this approximate linear response of the holdfast bulk with an effective spring constant, k. We defined the contact point Z 0 between the tip and sample as the distance where the F vs. D curve departs from the linear behavior 44,50,60,61 . Holdfast deformation is negligible under forces smaller than 5 nN (Fig.…”

Section: Dynamic Adhesion Force Spectroscopy Experiments Dynamicmentioning

confidence: 99%

Layered structure and complex mechanochemistry of a strong bacterial adhesive

Hernando-Pérez

Setayeshgar

Hou

et al. 2017

Preprint

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While designing adhesives that perform in aqueous environments has proven challenging for synthetic adhesives, microorganisms commonly produce bioadhesives that efficiently attach to a variety of substrates, including wet surfaces that remain a challenge for industrial adhesives. The aquatic bacterium Caulobacter crescentus uses a discrete polar polysaccharide complex, the holdfast, to strongly attach to surfaces and resist flow. The holdfast is extremely versatile and has an impressive adhesive strength. Here, we use atomic force microscopy (AFM) to unravel the complex structure of the holdfast and characterize its chemical constituents and their role in adhesion. We used purified holdfasts to dissect the intrinsic properties of this component as a biomaterial, without the effect of the bacterial cell body. Our data support a model where the holdfast is a heterogeneous material composed of two layers: a stiff nanoscopic core, covered by a sparse, flexible brush layer. These two layers contain not only N-acetyl-D-glucosamine (NAG), the only yet identified component present in the holdfast, but also peptides and DNA, which provide structure and adhesive character. Biochemical experiments suggest that, while polypeptides are the most important components for adhesive force, the presence of DNA mainly impacts the brush layer and initial adhesion, and NAG plays a primarily structural role within the core. Moreover, our results suggest that holdfast matures structurally, becoming more homogeneous over time. The unanticipated complexity of both the structure and composition of the holdfast likely underlies its distinctive strength as a wet adhesive and could inform the development of a versatile new family of adhesives.

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Quantitative nanoscale electrostatics of viruses

Cited by 54 publications

References 52 publications

Cargo–shell and cargo–cargo couplings govern the mechanics of artificially loaded virus-derived cages

Cargo–shell and cargo–cargo couplings govern the mechanics of artificially loaded virus-derived cages

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

Layered structure and complex mechanochemistry of a strong bacterial adhesive

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