Molecular basis for the functional interaction of dynein light chain with the nuclear-pore complex

Abstract

Nucleocytoplasmic transport occurs through nuclear pore complexes (NPCs) embedded in the nuclear envelope. Here, we discovered an unexpected role for yeast dynein light chain (Dyn2) in the NPC. Dyn2 is a previously undescribed nucleoporin that functions as molecular glue to dimerize and stabilize the Nup82-Nsp1-Nup159 complex, a module of the cytoplasmic pore filaments. Biochemical analyses showed that Dyn2 binds to a linear motif (termed DID(Nup159)) inserted between the Phe-Gly repeat and coiled-coil domain of Nup159. Electron microscopy revealed that the reconstituted Dyn2-DID(Nup159) complex forms a rigid rod-like structure, in which five Dyn2 homodimers align like 'pearls on a string' between two extented DID(Nup159) strands. These findings imply that the rigid 20 nm long Dyn2-DID(Nup159) filament projects the Nup159 Phe-Gly repeats from the Nup82 module. Thus, it is possible that dynein light chain plays a role in organizing natively unfolded Phe-Gly repeats within the NPC scaffold to facilitate nucleocytoplasmic transport.

PEX14 is required for microtubule-based peroxisome motility in human cells

“…In Pichia pastoris, PEX14 interacts directly or indirectly with ATG30, which is a key player in the selection of peroxisomes for their delivery to the autophagy machinery (Farre et al, 2009). In Saccharomyces cerevisiae, an interaction between PEX14 and the actin binding domain LC8 was reported (Stelter et al, 2007). In this respect, it is noteworthy that pexophagy in yeast involves the actin filaments rather than microtubules (Reggiori et al, 2005).…”

A Genomewide RNAi Screen for Genes That Affect the Stability, Distribution and Function of P Granules in Caenorhabditis elegans

“…Nuclear lamin LMN-1 is also required, as is dynein light chain-1, DLC-1. DLC-1's yeast homolog DYN2 is a nucleoporin (Stelter et al 2007), and interestingly C. elegans DLC-1 was found to interact with PGL-3 in a high-throughput binding assay (Li et al 2004). Therefore, it is possible that some nucleoporins, like the putative nucleoporin DLC-1, provide a physical linkage between P granules and nuclear pores.…”

Multiple Recognition Motifs in Nucleoporin Nup159 Provide a Stable and Rigid Nup159-Dyn2 Assembly

“…Although it is clear that binding of Dyn2 does not require ubiquitylation of Nup159 (this work and Ref. 5), it is possible that ubiquitylation of Nup159 may increase its binding affinity to Dyn2 so that it is more tightly anchored to the nuclear pore complex. Hayakawa et al (43) also report that preventing ubiquitylation alters the nuclear segregation and the spindle positioning at the onset of mitosis, roles that are attributed to the cytoplasmic dynein complex.…”

“…In single particle electron micrographs (EM), the Nup-Dyn2 complex forms an elongated structure described as "beads on a string," which has been proposed to project the N-terminal Phe-Gly repeats into the cytoplasm where they are accessible to nuclear transport proteins at the cytoplasmic end of the nuclear pore (5). A Nup construct containing only the first three motifs is too flexible to be observed by EM, supporting the idea that the last two motifs impart rigidity.…”