Structural studies on the LINC complex and Fic-1

Abstract

LINC complexes span the nuclear envelope and connect the nucleoskeleton to the cytoskeleton. In 2012, our lab solved the first LINC complex structure, that of SUN domain of human SUN2 bound with KASH1 or KASH2 peptides. In this project testes-specific human SUN proteins (SUN3, SPAG4, and SUNS) were compared to ubiquitously-expressed SUN2. Secondly, fission and budding yeast LINC complexes differ from human ones and were analyzed as well. I was able to confirm SUN-KASH interaction in human and yeast. For structural analysis I explored various expression strategies. Fic-1 is a C. elegans Fic-domain protein with diverse cellular functions. As a subfamily III Fic enzyme, Fic-1 may reveal valuable insights into Fic enzyme mechanisms from its structure. After trying different knowledge-informed constructs and crystal optimization, small Fic-1 crystals were obtained, which diffracted X-rays to ~ 7 [angstroms]. With modest additional effort diffraction-quality crystals should be achievable.