Novel CIPK1-associated proteins in Arabidopsis contain an evolutionarily conserved C-terminal region that mediates nuclear localization.
Environmental stimuli, including light, pathogens, hormones, and abiotic stresses, elicit changes in the cytosolic Ca(2+) signatures of plant cells. However, little is known about the molecular mechanisms by which plants sense and transmit the specific cytoplasmic Ca(2+) signal into the nucleus, where gene regulation occurs to respond appropriately to the stress. In this study, we have identified two novel Arabidopsis (Arabidopsis thaliana) proteins specifically associated with Calcineurin B-Like-Interacting Protein Kinase1 (CIPK1), a member of Ser/Thr protein kinases that interact with the calcineurin B-like Ca(2+)-binding proteins. These two proteins contain a very similar C-terminal region (180 amino acids in length, 81% similarity), which is required and sufficient for both interaction with CIPK1 and translocation to the nucleus. Interestingly, the conserved C-terminal region was also found in many proteins from various eukaryotic organisms, including humans. However, none of them have been characterized so far. Taken together, these findings suggest that the two proteins containing the evolutionarily conserved C-terminal region (ECT1 and ECT2) may play a critical role in relaying the cytosolic Ca(2+) signals to the nucleus, thereby regulating gene expression.
Ok
Sung Han
SH
Department of Molecular Biology, Sejong University, Seoul, Korea.
Jeong
Hye Jin
HJ
Bae
Jung Myung
JM
Shin
Jeong-Sheop
JS
Luan
Sheng
S
Kim
Kyung-Nam
KN
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000166:cytology / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D020013:Calcium Signaling; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D017124:Conserved Sequence; D019143:Evolution, Molecular; D018506:Gene Expression Regulation, Plant; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D011485:Protein Binding; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D021381:Protein Transport; D017386:Sequence Homology, Amino Acid
D029681:Arabidopsis Proteins; D002135:Calcium-Binding Proteins; C507142:ECT1 protein, Arabidopsis; C507143:ECT2 protein, Arabidopsis; D047908:Intracellular Signaling Peptides and Proteins; C483419:calcineurin B-like protein 1, Arabidopsis; C507144:CIPK1 protein, Arabidopsis; D017346:Protein Serine-Threonine Kinases