#Nuclear envelope function verification#

S2 G), which is critical for interacting with the SUN domain and for NE localization ( Padmakumar et al., 2005 Ketema et al., 2007 Morimoto et al., 2012 Sosa et al., 2012 Zhou et al., 2012a). The KASH domains of opisthokont KASH proteins and plant WIPs terminate in a C-terminal 4-aa motif ( Fig. Plant genomes do not encode any homologues of known opisthokont KASH proteins. SINE1 is predominantly expressed in guard cells, is associated with F-actin, and is involved in centrally positioning guard cell nuclei, whereas SINE2 is predominantly expressed in other leaf cell types, shows no association with F-actin, and contributes to innate immunity against an oomycete pathogen. thaliana SINE1 and SINE2 are conserved across land plants and have distinct expression profiles and functions in leaves. We show that all five proteins are localized to the NE, and this localization depends on their interaction with the SUN domain of SUN proteins.

#Nuclear envelope function verification#

Here, we describe this approach and the experimental verification of five candidates from four protein families. Identifying plant NETs is critical to resolve this enigma.Д«ased on detailed knowledge of opisthokont SUNвЂ“KASH complex formation ( Sosa et al., 2012 Zhou et al., 2012b) and the known conservation of the KASH domains, we reasoned that a computational approach could be developed to discover unknown KASH proteins in plants and provide better understanding of the KASH subset of plant NETs.

In light of the fact that open mitosis has likely evolved at least twice ( De Souza and Osmani, 2007 Meier et al., 2008 Becker and Marin, 2009), there may be a much deeper functional and compositional divide between opisthokont and land plant NEs. This is in stark contrast to the nuclear pore complex, which seems to have been established at the time of the last eukaryotic common ancestor ( Neumann et al., 2010). However, the protein complement of the opisthokont NE appears to be largely missing from land plants, whereas several plant-unique NE proteins have been described ( Meier, 2001 Gruenbaum et al., 2003 Xu et al., 2007 Zhao et al., 2008 Graumann and Evans, 2010). However, studies in opisthokonts have revealed that, at the molecular level, the NE is a regulatory platform containing NE transmembrane proteins (NETs) involved in nuclear positioning, nuclear mechanics (shape, volume, and rigidity), gene expression, and genome organization, which are essential for cell migration, stability, division, and proliferation ( Mekhail and Moazed, 2010 Starr and Fridolfsson, 2010 Hampoelz and Lecuit, 2011 Zuleger et al., 2011b). This study dramatically expands our knowledge of plant KASH proteins and suggests that plants and opisthokonts have recruited different KASH proteins to perform NE regulatory functions.ДЄt the basic structural level, the nuclear envelope (NE) is a protective barrier of the genome. Of those, Arabidopsis thaliana SINE1 is involved in actin-dependent nuclear positioning in guard cells, whereas its paralogue SINE2 contributes to innate immunity against an oomycete pathogen. Ten potential plant KASH protein families were identified, and five candidates from four of these families were verified for their NE localization, depending on SUN domain interaction. Based on similarities between opisthokont KASH proteins and the only known plant KASH proteins, WPP domainвЂ“interacting proteins, we used a computational method to identify the KASH subset of plant NETs. Therefore, de novo identification of plant NETs is necessary. The only known NET homologues in plants are Sad1/UNC-84 (SUN) proteins, which bind Klarsicht/ANC-1/Syne-1 homology (KASH) proteins. Although a plethora of nuclear envelope (NE) transmembrane proteins (NETs) have been identified in opisthokonts, plant NETs are largely unknown.