Single DNA molecule jamming and history-dependent dynamics during motor-driven viral packaging.
Single DNA molecule jamming and history-dependent dynamics during motor-driven viral packaging.
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DOI：
10.1038/nphys3740
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发表时间：
2016-08
期刊：
影响因子：
19.6
通讯作者：
Smith DE
中科院分区：
文献类型：
--
作者：
Keller N;Grimes S;Jardine PJ;Smith DE
在许多病毒中，分子发动机将单个DNA分子以接近晶体的密度强行包装到约50-100 nm的前壳中。出乎意料的是，我们发现包装经常在诱导净吸引力DNA-DNA相互作用的条件下停滞。在这里，我们提出的研究结果表明，这种失速发生，因为DNA经历了一个非平衡的干扰过渡类似于在许多软物质系统，如胶体和颗粒系统中观察到的。在包装过程中改变条件以在纯排斥和净吸引之间切换DNA-DNA相互作用的实验揭示了强烈的历史依赖性动力学。通常在失速之前观察到突然减速，表明DNA构象的转变导致电阻突然增加。我们的研究结果表明，堵塞的概念可以扩展到一个单一的聚合物分子。然而，与宏观样品的胶体颗粒相比，我们发现，单个DNA分子堵塞在一个更大的范围内的密度。我们将这种差异归因于纳米尺度的系统尺寸，这与理论预测的有吸引力的非热粒子干扰一致。
In many viruses molecular motors forcibly pack single DNA molecules to near-crystalline density into ~50–100 nm prohead shells. Unexpectedly, we found that packaging frequently stalls in conditions that induce net attractive DNA-DNA interactions. Here, we present findings suggesting that this stalling occurs because the DNA undergoes a nonequilibrium jamming transition analogous to that observed in many soft-matter systems, such as colloidal and granular systems. Experiments in which conditions are changed during packaging to switch DNA-DNA interactions between purely repulsive and net attractive reveal strongly history-dependent dynamics. An abrupt deceleration is usually observed before stalling, indicating that a transition in DNA conformation causes an abrupt increase in resistance. Our findings suggest that the concept of jamming can be extended to a single polymer molecule. However, compared with macroscopic samples of colloidal particles we find that single DNA molecules jam over a much larger range of densities. We attribute this difference to the nanoscale system size, consistent with theoretical predictions for jamming of attractive athermal particles.