Nanoelectrochemical Study of Molecular Transport through the Nuclear Pore Complex

描述（由申请人提供）：该项目的长期目标是获得通过核孔复合物（NPC）的分子运输的更大的机制理解。这一目标的实现在医学、生物学、化学和纳米科学领域具有根本性和广泛的意义，随后，它将对更好的人类健康产生强大而持久的影响。在这项工作中，我们提出并验证了通过NPC的分子运输在纳米尺度上受到空间调节的新假设。具体来说，我们假设NPC纳米孔的内部被富含苯丙氨酸和甘氨酸的疏水运输屏障同心地分为中央和外周路线。此外，我们假设外周途径被更灵活的屏障更松散地阻断，从而更容易渗透到大分子的核输入中。值得注意的是，这一假设意味着外围途径应该针对核

DESCRIPTION (provided by applicant): The long-term goal of this project is to obtain a greater mechanistic understanding of molecular transport through the nuclear pore complex (NPC). The fulfillment of this goal is fundamentally and broadly significant in medicine, biology, chemistry, and nanoscience, and, subsequently, it will make a powerful, sustained impact on better human health. In this work, we propose and test the novel hypothesis that molecular transport through the NPC is spatially regulated at the nanometer scale. Specifically, we hypothesize that the interior of the NPC nanopore is concentrically divided into central and peripheral routes by the hydrophobic transport barriers that are rich in phenylalanine and glycine. In addition, we hypothesize that the peripheral route is more loosely blocked by more flexible barriers to be more readily permeabilized for the nuclear import of macromolecules. Significantly, this hypothesis implies that the peripheral route should be targeted for the nuclear import of therapeutic macromolecules and nanomaterials for gene therapy and nanomedicine. We will test these hypotheses by measuring the permeability of central and peripheral routes to various probe molecules by using newly developed methodologies. Our transport study will reveal not only the higher permeability of the peripheral route but also the types of the interactions, e.g., hydrophobic, steric, and electrostatic, that each transport barrier exerts on a probe molecule. Innovatively, we will directly resolve molecular transport through each route of the single NPC by using scanning electrochemical microscopy (SECM) with an unprecedentedly high spatial resolution of <10 nm. The results of this single-NPC imaging will be quantitatively compared with those of the well-established micrometer-scale SECM study of multiple NPCs. These SECM studies are focused on the passive transport of small probe molecules and they are complemented by the confocal fluorescence microscopic study of macromolecular transport through multiple NPCs. Molecular transport through multiple NPCs can be studied with pathway selectivity by employing the proteins or small molecules that can selectively block or permeabilize a target route, respectively.