Structural and Functional Studies of Nup107/Nup133 Interaction and Its Implications for the Architecture of the Nuclear Pore Complex

Abstract

Nuclear pore complexes (NPCs) are 40-60 MDa protein assemblies embedded in the nuclear envelope of eukaryotic cells. NPCs exclusively mediate all transport between cytoplasm and nucleus. The nucleoporins that build the NPC are arranged in a stable core of module-like subcomplexes with eight-fold rotational symmetry. To gain insight into the intricate assembly of the NPC, we have solved the crystal structure of a protein complex between two nucleoporins, human Nup107 and Nup133. Both proteins form elongated structures that interact tightly via a compact interface in tail-to-tail fashion. Additional experiments using structure-guided mutants show that Nup107 is the critical anchor for Nup133 to the NPC, positioning Nup133 at the periphery of the NPC. The significant topological differences between Nup107 and Nup133 suggest that *-helical nucleoporin domains of the NPC scaffold fall in different classes and fulfill largely nonredundant functions.

Structure of a trimeric nucleoporin complex reveals alternate oligomerization states

“…Here, we have fitted crystal structures of Sec13⅐Nup145C⅐Nup84 NTD, a large Nup120 fragment (34), the Seh1⅐Nup85 pair (27), the human Nup107 CTD⅐Nup133 CTD complex (25), and the human Nup133 NTD (34) into the EM envelopes of the two conformations (Fig. 6).…”

“…This analysis identified specific hinge regions at which the heptamer shows great flexibility, and allowed for the docking of atomic structures of its components into the EM envelope: the Nup133 N-terminal domain (24), Nup107⅐Nup133 (Nup107 is the human homolog of Nup84) (25), Sec13⅐Nup145C (26), and Seh1⅐Nup85 (27).…”

The discovery of a Werner helicase interacting protein (WHIP) association with the nuclear pore complex

“…Abbreviations: NE, nuclear envelope; NPC, nuclear pore complex; Nups, nucleoporins; WHIP, Werner helicase interacting protein 1; WRN, Werner's protein; NP, nucleoplasm; CE, cell extract; NEx, nuclear extract (coiled coils, β-propellers or disordered areas) [11][12][13][14][15] while FG Nups contain flexible repeating units of phenylalanine-glycine and are implicated in active nuclear transport. 2,3 In higher eukaryotic cells undergoing an open mitosis, the NPC is disassembled into a smaller collection of Nups termed subcomplexes.…”

Structural and functional analysis of Nup120 suggests ring formation of the Nup84 complex

“…To date, partial atomic structures of several components of the heptameric complex have been determined: the ␤ propeller of Nup133 (29), the Sec13⅐Nup145C pair (30), the mammalian Nup84 homolog Nup107 in complex with Nup133 (31), and the Seh1⅐Nup85 pair (32,33). But atomic-level knowledge of how these modules are precisely arranged and interact with one another in the heptameric complex remains largely elusive.…”