Characterization of SUN-domain proteins at the higher plant nuclear envelope
Article first published online: 4 NOV 2009
© 2009 The Authors. Journal compilation © 2009 Blackwell Publishing Ltd
The Plant Journal
Volume 61, Issue 1, pages 134–144, January 2010
How to Cite
Graumann, K., Runions, J. and Evans, D. E. (2010), Characterization of SUN-domain proteins at the higher plant nuclear envelope. The Plant Journal, 61: 134–144. doi: 10.1111/j.1365-313X.2009.04038.x
- Issue published online: 18 DEC 2009
- Article first published online: 4 NOV 2009
- Received 21 July 2009; revised 7 September 2009; accepted 29 September 2009; published online 4 November 2009.
- nuclear envelope;
- SUN domain;
- INM targeting;
- LINC complex
Sad1/UNC-84 (SUN)-domain proteins are inner nuclear membrane (INM) proteins that are part of bridging complexes linking cytoskeletal elements with the nucleoskeleton, and have been shown to be conserved in non-plant systems. In this paper, we report the presence of members of this family in the plant kingdom, and investigate the two Arabidopsis SUN-domain proteins, AtSUN1 and AtSUN2. Our results indicate they contain the highly conserved C-terminal SUN domain, and share similar structural features with animal and fungal SUN-domain proteins including a functional coiled-coil domain and nuclear localization signal. Both are expressed in various tissues with AtSUN2 expression levels relatively low but upregulated in proliferating tissues. Further, we found AtSUN1 and AtSUN2 expressed as fluorescent protein fusions, to localize to and show low mobility in the nuclear envelope (NE), particularly in the INM. Deletion of various functional domains including the N terminus and coiled-coil domain affect the localization and increase the mobility of AtSUN1 and AtSUN2. Finally, we present evidence that AtSUN1 and AtSUN2 are present as homomers and heteromers in vivo, and that the coiled-coil domains are required for this. The study provides evidence suggesting the existence of cytoskeletal–nucleoskeletal bridging complexes at the plant NE.