title: The Nup62 Coiled-Coil Motif Provides Plasticity for Triple-Helix Bundle Formation.
abstract: The central transport channel of the vertebrate nuclear pore complex (NPC) consists of nucleoporins: Nup62, Nup54, and Nup58. The coiled-coil domains in α-helical regions of these nucleoporins are thought to be crucial for several protein-protein interactions in the NPC subcomplexes. In this study, we determined the crystal structure of the coiled-coil domain of rat Nup62 fragment (residues 362-425) to 2.4 Å resolution. The crystal structure shows the conserved coiled-coil domain as a parallel three-helix bundle for the Nup62(362-425) fragment. On the basis of our size exclusion chromatography coupled to multiangle light scattering analysis and glutaraldehyde cross-linking experiments, we conclude that the Nup62(362-425) fragment displays dynamic behavior in solution and can also exist in either homodimeric or homotrimeric states. Our comparative analysis of the rat Nup62(362-425) homotrimeric structure with previously reported heterotrimeric structures [rat Nup62(362-425)·Nup54(346-407) and Xenopus Nup62(358-485)·Nup54(315-450)·Nup58(283-406) complexes] demonstrates the structural basis for parallel triple-helix bundle formation for Nup62 with different partners. Moreover, we show that the coiled-coil domain of Nup62 is sufficient for interaction with the coiled-coil domain of rat Exo70, a protein in an exocyst complex. On the basis of these observations, we suggest the plausible chain replacement mechanism that yields to diverse protein assemblies with Nup62. In summary, the coiled-coil motif present in Nup62 imparts the ability to form a homotrimer and heterotrimers either with Nup54 or with Nup54-Nup58 within the NPCs as well as with Exo70 beyond the NPCs. These complexes of Nup62 suggest the crucial role of the coiled-coil motifs in providing plasticity to various modular assemblies.
authors.affiliation: National Centre for Cell Science , S. P. Pune University Campus, Ganeshkhind, Pune 411007, India.
authors.forename: Pravin S
authors.identifier: 0000-0003-1632-1637
authors.initials: PS
authors.lastname: Dewangan
authors.affiliation: National Centre for Cell Science , S. P. Pune University Campus, Ganeshkhind, Pune 411007, India.
authors.forename: Parshuram J
authors.initials: PJ
authors.lastname: Sonawane
authors.affiliation: National Centre for Cell Science , S. P. Pune University Campus, Ganeshkhind, Pune 411007, India.
authors.forename: Ankita R
authors.initials: AR
authors.lastname: Chouksey
authors.affiliation: National Centre for Cell Science , S. P. Pune University Campus, Ganeshkhind, Pune 411007, India.
authors.forename: Radha
authors.initials: R
authors.lastname: Chauhan
mesh_terms: D000818:Animals; D002850:Chromatography, Gel; D018360:Crystallography, X-Ray; D008562:Membrane Glycoproteins / Q000737:chemistry*; D028861:Nuclear Pore Complex Proteins / Q000737:chemistry*; D051381:Rats
chemical_list: D008562:Membrane Glycoproteins; D028861:Nuclear Pore Complex Proteins; C049312:nuclear pore protein p62