Yeast centrosome components form a noncanonical LINC complex at the nuclear envelope insertion site.

Jingjing Chen,Sean Mckinney,Jennifer M Gardner,Sarah E Smith,Brian D Slaughter,Zulin Yu,Sue L Jaspersen,Jay R Unruh

doi:10.1083/jcb.201809045

Abstract

Bipolar spindle formation in yeast requires insertion of centrosomes (known as spindle pole bodies [SPBs]) into fenestrated regions of the nuclear envelope (NE). Using structured illumination microscopy and bimolecular fluorescence complementation, we map protein distribution at SPB fenestrae and interrogate protein-protein interactions with high spatial resolution. We find that the Sad1-UNC-84 (SUN) protein Mps3 forms a ring-like structure around the SPB, similar to toroids seen for components of the SPB insertion network (SPIN). Mps3 and the SPIN component Mps2 (a Klarsicht-ANC-1-Syne-1 domain [KASH]-like protein) form a novel noncanonical linker of nucleoskeleton and cytoskeleton (LINC) complex that is connected in both luminal and extraluminal domains at the site of SPB insertion. The LINC complex also controls the distribution of a soluble SPIN component Bbp1. Taken together, our work shows that Mps3 is a fifth SPIN component and suggests both direct and indirect roles for the LINC complex in NE remodeling.

Highlights

The double lipid bilayer of the nuclear membrane serves as a physical barrier to restrict movement of macromolecules from the cytoplasm to nucleus, or vice versa
Genetic analysis suggests that spindle pole body (SPB) incorporation into the nuclear envelope (NE) requires at least four factors: a soluble SPB protein, Bbp1; an amphipathic domain-containing protein, Nbp1; the dual SPB-nuclear pore complexes (NPCs) transmembrane protein Ndc1; and a Klarsicht-ANC-1-Snye-1 homology (KASH)–like protein, Mps2 (Winey et al, 1991; Chial et al, 1998; Muñoz-Centeno et al, 1999; Schramm et al, 2000; Araki et al, 2006)
Radial distribution of SPB insertion network (SPIN) components using 3D particle averaging The SPB is a multilayered cylindrical organelle permanently embedded in the NE

Summary

Introduction

The double lipid bilayer of the nuclear membrane serves as a physical barrier to restrict movement of macromolecules from the cytoplasm to nucleus, or vice versa. The SPIN component Ndc1 can be seen surrounding the SPB core (Spc42) using SIM in diploid cells, which have a diameter (160 nm) that is above the resolution limit (∼100 nm; Fig. 1, A and B).

Results

Conclusion