Department of Physics of the Condensed Matter, Universidad Autónoma de Madrid, 28049 Madrid, Spain.
Department of Structure of Macromolecules, Centro Nacional de Biotecnología (CNB-CSIC), Darwin 3, 28049 Madrid, Spain.
Nanoscale. 2016 Apr 28;8(17):9328-36. doi: 10.1039/c6nr01007e.
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.
核酸是病毒的天然载体，也是影响病毒外壳稳定性的关键决定因素。在某些情况下，基因组结构上增强了外壳，而在其他情况下，基因组包装会导致内部压力，从而引起外壳的不稳定性。尽管可以将异源货物包装在源自病毒的外壳内，但对于这些人工纳米容器稳定性的物理决定因素知之甚少。原子力显微镜和三维低温电子显微镜提供了有关病毒笼稳定的物理机制的机械和结构信息，超出了仅仅存在/不存在货物的范围。我们分析了封装两种类型的蛋白质有效载荷后，货物-外壳和货物-货物相互作用对外壳稳定性的影响。虽然结合到内壳表面的货物以结构方式机械地增强了外壳，但由于空间位阻的影响，在壳腔中自由扩散的未结合货物会对内笼加压至约 30 大气压。当与外壳结合时，货物-货物之间的强耦合会使这些纳米隔室的弹性降低约 20%。了解人工装载的纳米笼的稳定性将有助于设计更坚固和耐用的分子纳米容器。
