2 research outputs found
The Nup62 Coiled-Coil Motif Provides Plasticity for Triple-Helix Bundle Formation
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 Ã… resolution. The crystal structure shows the conserved
coiled-coil domain as a parallel three-helix bundle for the Nup62Â(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 <i>Xenopus</i> 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