The electrical conductivity of biomaterials on a molecular scale is fundamental interest in the life sciences. We perform first principles electronic structure calculations, which clearly indicate that $\ensuremath{\lambda}$-DNA chains should present large resistance values. also two direct procedures to measure currents through DNA molecules adsorbed mica. lower limit for resistivity ${10}^{6}\phantom{\rule{0ex}{0ex}}\ensuremath{\Omega}\ifmmode \dot{}\else \.{}\fi{}\mathrm{cm}$, agreement...

The shell of bacteriophages protects the viral DNA during host-to-host transfer and serves as a high-pressure container storing energy for injection into host bacterium. Here, we probe mechanical properties nanometer-sized bacteriophage φ29 shells by applying point forces. We show that empty withstand nanonewton forces while being indented up to 30% their height. elastic response varies across surface, reflecting arrangement proteins. measured Young's modulus (≈1.8 GPa) is comparable with...

We probe the local mechanical properties of microtubules at nanometer scale by radial indentation with a scanning force microscope tip. find linear elastic regime that can be described both thin-shell theory and finite element methods, in which are modeled as hollow tubes. also nonlinear catastrophic collapse under large loads. The main physics protein shells shows simultaneously aspects continuum elasticity their response, well molecular graininess behavior.

In this work, we provide evidence of a mechanism to reinforce the strength an icosahedral virus by using its genomic DNA as structural element. The mechanical properties individual empty capsids and DNA-containing virions minute mice are investigated atomic force microscopy. stiffness capsid is found be isotropic. Remarkably, presence inside virion leads anisotropic reinforcement approximately 3%, 40%, 140% along fivefold, threefold, twofold symmetry axes, respectively. A finite element...

In this letter, we present a new scanning probe microscopy mode, jumping which allows the simultaneous measurement of topography and some other physical property sample. Essentially, at each image point first sample is measured during feedback phase cycle, then tip–sample interaction evaluated in real time as tip moved away towards Since lateral motion done out contact method free, or nearly shear forces. The general advantages mode are discussed. Finally, two different applications...

A fundamental requirement for a molecule to be considered molecular wire (MW) is the ability transport electrical charge with reasonably low resistance. We have carried out two experiments that measure first, transfer from an electrode molecule, and second, dielectric response of MW. The latter experiment requires no contacts either end molecule. From our we conclude adsorbed individual DNA molecules resistivity similar mica, glass, silicon oxide substrates. Therefore not conductor, it...

We study the physical origins of phase contrast in dynamic atomic force microscopy (dAFM) liquids where low-stiffness microcantilever probes are often used for nanoscale imaging soft biological samples with gentle forces. Under these conditions, we show that derives primarily from a unique energy flow channel opens up due to momentary excitation higher eigenmodes. Contrary common assumption, phase-contrast images using microcantilevers maps short-range conservative interactions, such as...

In a previous study, we showed that the DNA molecule within spherical virus (the minute of mice) plays an architectural role by anisotropically increasing mechanical stiffness virus. A finite element model predicted this reinforcement is consequence interaction between crystallographically visible, short patches and inner capsid wall. We have now tested using protein engineering. Selected amino acid side chains been truncated to specifically remove major interactions visible patches, effect...

Abstract The standard pathway for virus infection of eukaryotic cells requires disassembly the viral shell to facilitate release genome into host cell. Here we use mechanical fatigue, well below rupture strength, induce stepwise disruption individual human adenovirus particles under physiological conditions and simultaneously monitor in real time. Our data show sequence dismantling events mature (infectious) immature (noninfectious) virions, starting with consecutive vertex structures...

Tight confinement of naked genomes within some viruses results in high internal pressure that facilitates their translocation into the host. Adenovirus, however, encodes histone-like proteins associate with its genome resulting a confined DNA–protein condensate (core). Cleavage these during maturation decreases core condensation and primes virion for proper uncoating via unidentified mechanisms. Here we open individual, mature immature adenovirus cages to directly probe mechanics...

Using AFM nanoindentation experiments, DNA-full phi29 phage capsids are shown to be stiffer than when empty. The presence of counterions softens full viruses in a reversible manner, indicating that pressure originates from the confined DNA. A finite element analysis experiments provides an estimate ∼40 atm inside capsid, which is similar theoretical predictions. Detailed facts importance specialist readers published as "Supporting Information". Such documents peer-reviewed, but not...

Electrostatics is one of the fundamental driving forces interaction between biomolecules in solution. In particular, recognition events viruses and host cells are dominated by both specific non-specific interactions electric charge viral particles determines electrostatic force component latter. Here we probe individual liquid milieu measuring a particle Atomic Force Microscope tip. The spectroscopy data co-adsorbed ϕ29 bacteriophage proheads mature virions, adenovirus minute virus mice...

Viruses package their genome in a robust protein coat to protect it during transmission between cells and organisms. In reaction termed uncoating, the virus is progressively weakened entry into cells. At end of uncoating process separates, becomes transcriptionally active, initiates production progeny. Here, we triggered disruption single human adenovirus capsids with atomic force microscopy followed exposure by single-molecule fluorescence microscopy. This method allowed comparison immature...

Abstract The assembly and regulation of viral capsid proteins into highly ordered macromolecular complexes is essential for replication. Here, we utilize crystal structures the protein from smallest simplest known viruses capable autonomously replicating in animal cells, circoviruses, to establish structural mechanistic insights morphogenesis regulation. beak feather disease virus, like many encode only two genes: a replication initiation protein. forms distinct assemblies during here...

A simple method of making reliable electrical contact to multiwalled carbon nanotubes is described. With these contacts, current in the mA range can be routinely passed through individual without adverse consequences, thus allowing their resistance measured using a common multimeter. The contacts are robust enough withstand temperature excursions between room and 77 K. I(V) data from different presented analyzed.

In this study we test the hypothesis that mechanically elastic regions in a virus particle (or large biomolecular complex) must coincide with conformationally dynamic regions, because both properties are intrinsically correlated. Hypothesis-derived predictions were subjected to verification by using 19 variants of minute mice capsid. The structural modifications these reduced, preserved, or restored conformational dynamism surrounding capsid pores involved molecular translocation events...

Nucleic acids are the natural cargo of viruses and key determinants that affect viral shell stability. In some cases genome structurally reinforces shell, whereas in others packaging causes internal pressure can induce destabilization. Although it is possible to pack heterologous cargoes inside virus-derived shells, little known about physical these artificial nanocontainers' Atomic force three-dimensional cryo-electron microscopy provided mechanical structural information mechanisms cage...