LINC Complexes Form by Binding of Three KASH Peptides to Domain Interfaces of Trimeric SUN Proteins

Sosa, Brian A; Rothballer, Andrea; Kutay, Ulrike; Schwartz, Thomas

doi:10.1016/j.cell.2012.03.046

Cited by 348 publications

(595 citation statements)

References 64 publications

Supporting

Mentioning

550

Contrasting

Order By: Relevance

“…Our structural and biochemical studies strongly indicate that the SUN domain homotrimer is a primary KASH-binding unit, consistent with a recent independent report of the SUN-KASH complex structure [33]. However, it was recently found that both SUN proteins and KASH proteins can form high-order oligomers or clusters during specific cellular events [23,[34][35][36][37][38][39].…”

Section: Discussionsupporting

confidence: 75%

See 1 more Smart Citation

Structural insights into SUN-KASH complexes across the nuclear envelope

et al. 2012

View full text Add to dashboard Cite

Linker of the nucleoskeleton and the cytoskeleton (LINC) complexes are composed of SUN and KASH domaincontaining proteins and bridge the inner and outer membranes of the nuclear envelope. LINC complexes play critical roles in nuclear positioning, cell polarization and cellular stiffness. Previously, we reported the homotrimeric structure of human SUN2. We have now determined the crystal structure of the human SUN2-KASH complex. In the complex structure, the SUN domain homotrimer binds to three independent "hook"-like KASH peptides. The overall conformation of the SUN domain in the complex closely resembles the SUN domain in its apo state. A major conformational change involves the AA'-loop of KASH-bound SUN domain, which rearranges to form a mini β-sheet that interacts with the KASH peptide. The PPPT motif of the KASH domain fits tightly into a hydrophobic pocket on the homotrimeric interface of the SUN domain, which we termed the BI-pocket. Moreover, two adjacent protomers of the SUN domain homotrimer sandwich the KASH domain by hydrophobic interaction and hydrogen bonding. Mutations of these binding sites disrupt or reduce the association between the SUN and KASH domains in vitro. In addition, transfection of wild-type, but not mutant, SUN2 promotes cell migration in Ovcar-3 cells. These results provide a structural model of the LINC complex, which is essential for additional study of the physical and functional coupling between the cytoplasm and the nucleoplasm.

show abstract

Section: Discussionsupporting

confidence: 75%

“…A study by Sosa et al used sedimentation equilibrium analysis and suggested that the SUN complex was a homotrimer [33]. Nevertheless, large differences likely exist between the SUN-KASH microenvironment in cells and the solution conditions used for sedimentation equilibrium analysis.…”

Section: Discussionmentioning

confidence: 99%

Structural insights into SUN-KASH complexes across the nuclear envelope

et al. 2012

View full text Add to dashboard Cite

show abstract

“…The flat cisternae of the ONM and INM are separated by the distance of the INS (about 50 nm), which is held constant by the LINC complex ( Fig. 1A) (Tzur et al 2006;Sosa et al 2012). The membrane bilayers of the INM and ONM cisternae are continuous with each other at nuclear pores (NPs), providing a conduit for membrane proteins to diffuse between the nuclear and cytoplasmic compartments ( Fig.…”

mentioning

confidence: 99%

Endoplasmic Reticulum Structure and Interconnections with Other Organelles

English

Voeltz

2013

Cold Spring Harbor Perspectives in Biology

286

220

View full text Add to dashboard Cite

The endoplasmic reticulum (ER) is a large, continuous membrane-bound organelle comprised of functionally and structurally distinct domains including the nuclear envelope, peripheral tubular ER, peripheral cisternae, and numerous membrane contact sites at the plasma membrane, mitochondria, Golgi, endosomes, and peroxisomes. These domains are required for multiple cellular processes, including synthesis of proteins and lipids, calcium level regulation, and exchange of macromolecules with various organelles at ER-membrane contact sites. The ER maintains its unique overall structure regardless of dynamics or transfer at ER-organelle contacts. In this review, we describe the numerous factors that contribute to the structure of the ER.T he endoplasmic reticulum (ER) is a dynamic organelle responsible for many cellular functions, including the synthesis of proteins and lipids, and regulation of intracellular calcium levels. This review focuses on the distinct and complex morphology of the ER. The structure of the ER is complex because of the numerous distinct domains that exist within one continuous membrane bilayer. These domains are shaped by interactions with the cytoskeleton, by proteins that stabilize membrane shape, and by a homotypic fusion machinery that allows the ER membrane to maintain its continuity and identity. The ER also contains domains that contact the plasma membrane (PM) and other organelles including the Golgi, endosomes, mitochondria, lipid droplets, and peroxisomes. ER contact sites with other organelles and the PM are both abundant and dispersed throughout the cytoplasm, suggesting that they too could influence the overall architecture of the ER. As we will discuss here, ER shape and distribution are regulated by many intrinsic and extrinsic forces. ER STRUCTURE AND FORMATION Domains of the ER Are Stabilized by Membrane-Shaping ProteinsThe endoplasmic reticulum (ER) is a large membrane-bound compartment spread throughout the cytoplasm of eukaryotic cells. It is divided into three major morphologies that include the nuclear envelope (NE), peripheral ER cisternae, and an interconnected tubular network

show abstract

“…Without binding the KASH domain, the KASHlid conformation is rather random. 40 The very C-terminal "PPPX" motif is positioned in a KASH pocket formed by S641, Y703, Y707, H628 and the cation-loop (Q593-C601), which explains why these four amino acids are critical for SUN-KASH interactions. 40 …”

mentioning

confidence: 99%

“…39,40 In this complex, three KASH domains are anchored in one cloverleaf-like trimer of SUN domains. The SUN domain protomer has several functional domains: an α-helical stalk, a compact β-sandwich core, a cation-loop, and a protruding anti-parallel β-sheet named the KASH-lid ( fig.…”

mentioning

confidence: 99%