The nucleus is the inner sanctuary of the eukaryotic cell, keeping the genetic information enclosed by the nuclear envelope (NE). The NE consists of two concentric membrane bilayers fused at specific sites to form circular openings, each occupied by a nuclear pore complex (NPC). As the only gateway into and out of the nucleus, NPCs play a critical role in cellular homeostasis, but they are more than just transport complexes. We are beginning to appreciate that the NPC also serves as a reference point to organize the nucleus and plays a pivotal role in gene regulation. This research program focuses on determining the molecular architecture of the enormous ~40-80 MDa NPC. Attaining this goal will provide a structural basis to interrogate its myriad functions in transport, gene regulation, and nuclear organization. Importantly, aberrant function of the NPC and its constituents is a primary cause of many human diseases, including leukemia, other cancers, autoimmune diseases, cardiomyopathies, and a variety of viral infections. The NPC is a modular structure, composed of ~30 different proteins, known as nucleoporins that arrange in multiple copies around a central eightfold rotational axis. Subcomplexes of 2-10 nucleoporins hierarchically build up the NPC. Two of these subcomplexes, the heteromeric Y- and Nic96-complexes, organize the majority of architectural nucleoporins and establish the stable scaffold of the NPC. Crystallographic analysis of these subcomplexes by different labs combined with cryo-electron tomographic reconstitution has recently led to a first, vague assembly model. Here, we propose to fully structurally characterize the scaffold components of the NPC. Complemented by biochemical and cell biological methods, we hypothesize that we will generate the data to build a detailed structure of the NPC, the largest assembly structure in the eukaryotic cell. The proposal is centered on establishing the major building blocks of the NPC at near-atomic resolution, using a combination of X-ray crystallographic and electronmicroscopic techniques. A second focus of this study is to establish the interactome of all nucleoporins using experimental methods. This information will be critical in order to build a robust model of the NPC. Such a 3D rendition of the NPC can then be used to interrogate the NPC functions at a detailed, molecular level.

Public Health Relevance

This study will lead to a structural understanding of the massive nuclear pore complex (NPC), the sole transport channel to and from the cell's nucleus and the passage route for many pathogenic virus, including HIV. This knowledge will open mid-term possibilities to influence transport properties, possibly to block viral entry to the nucleus. The NPC is also involved in a myriad of other human diseases, including cancer and cardiomyopathies, thus a molecular understanding of these mechanisms may provide new long-term therapeutic strategies.

Agency
National Institute of Health (NIH)
Institute
National Institute of General Medical Sciences (NIGMS)
Type
Research Project (R01)
Project #
5R01GM077537-12
Application #
9537582
Study Section
Nuclear and Cytoplasmic Structure/Function and Dynamics Study Section (NCSD)
Program Officer
Flicker, Paula F
Project Start
2007-02-01
Project End
2020-07-31
Budget Start
2018-08-01
Budget End
2019-07-31
Support Year
12
Fiscal Year
2018
Total Cost
Indirect Cost
Name
Massachusetts Institute of Technology
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
001425594
City
Cambridge
State
MA
Country
United States
Zip Code
Onischenko, Evgeny; Tang, Jeffrey H; Andersen, Kasper R et al. (2017) Natively Unfolded FG Repeats Stabilize the Structure of the Nuclear Pore Complex. Cell 171:904-917.e19
Apelt, Luise; Knockenhauer, Kevin E; Leksa, Nina C et al. (2016) Systematic Protein-Protein Interaction Analysis Reveals Intersubcomplex Contacts in the Nuclear Pore Complex. Mol Cell Proteomics 15:2594-606
Schwartz, Thomas U (2016) The Structure Inventory of the Nuclear Pore Complex. J Mol Biol 428:1986-2000
Knockenhauer, Kevin E; Schwartz, Thomas U (2016) The Nuclear Pore Complex as a Flexible and Dynamic Gate. Cell 164:1162-1171
Kabachinski, Greg; Schwartz, Thomas U (2015) The nuclear pore complex--structure and function at a glance. J Cell Sci 128:423-9
Kelley, Kotaro; Knockenhauer, Kevin E; Kabachinski, Greg et al. (2015) Atomic structure of the Y complex of the nuclear pore. Nat Struct Mol Biol 22:425-431
Berchowitz, Luke E; Kabachinski, Greg; Walker, Margaret R et al. (2015) Regulated Formation of an Amyloid-like Translational Repressor Governs Gametogenesis. Cell 163:406-18
Ulrich, Alexander; Partridge, James R; Schwartz, Thomas U (2014) The stoichiometry of the nucleoporin 62 subcomplex of the nuclear pore in solution. Mol Biol Cell 25:1484-92
Andersen, Kasper R; Onischenko, Evgeny; Tang, Jeffrey H et al. (2013) Scaffold nucleoporins Nup188 and Nup192 share structural and functional properties with nuclear transport receptors. Elife 2:e00745
Andersen, Kasper R; Leksa, Nina C; Schwartz, Thomas U (2013) Optimized E. coli expression strain LOBSTR eliminates common contaminants from His-tag purification. Proteins 81:1857-61

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