A molecular mechanism for LINC complex branching by structurally diverse SUN-KASH 6:6 assemblies

• Main Authors: Manickam Gurusaran, Owen Richard Davies
• Format: Article
• Language: English
• Published: eLife Sciences Publications Ltd 2021-01-01
• Series: eLife
• Subjects: LINC complex; nuclear envelope; SUN1; Nesprin-1; Nesprin-4; KASH5
• Online Access: https://elifesciences.org/articles/60175

The Linker of Nucleoskeleton and Cytoskeleton (LINC) complex mechanically couples cytoskeletal and nuclear components across the nuclear envelope to fulfil a myriad of cellular functions, including nuclear shape and positioning, hearing, and meiotic chromosome movements. The canonical model is that 3:3 interactions between SUN and KASH proteins underlie the nucleocytoskeletal linkages provided by the LINC complex. Here, we provide crystallographic and biophysical evidence that SUN-KASH is a constitutive 6:6 complex in which two constituent 3:3 complexes interact head-to-head. A common SUN-KASH topology is achieved through structurally diverse 6:6 interaction mechanisms by distinct KASH proteins, including zinc-coordination by Nesprin-4. The SUN-KASH 6:6 interface provides a molecular mechanism for the establishment of integrative and distributive connections between 3:3 structures within a branched LINC complex network. In this model, SUN-KASH 6:6 complexes act as nodes for force distribution and integration between adjacent SUN and KASH molecules, enabling the coordinated transduction of large forces across the nuclear envelope.