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Identification of a calmodulin-binding NAC protein as a transcriptional repressor in Arabidopsis.

Authors :
Kim HS
Park BO
Yoo JH
Jung MS
Lee SM
Han HJ
Kim KE
Kim SH
Lim CO
Yun DJ
Lee SY
Chung WS
Source :
The Journal of biological chemistry [J Biol Chem] 2007 Dec 14; Vol. 282 (50), pp. 36292-302. Date of Electronic Publication: 2007 Oct 18.
Publication Year :
2007

Abstract

Calmodulin (CaM), a ubiquitous calcium-binding protein, regulates diverse cellular functions by modulating the activity of a variety of proteins. However, little is known about how CaM directly regulates transcription. Screening of an Arabidopsis cDNA expression library using horseradish peroxidase-conjugated calmodulin as a probe identified a calmodulin-binding NAC protein (CBNAC). Using gel overlay assays, a Ca2+-dependent CaM-binding domain was identified in the C terminus of this protein. Specific binding of CaM to CaM-binding domain was corroborated by site-directed mutagenesis and a split-ubiquitin assay. Using a PCR-mediated random binding site selection method, we identified a DNA-binding sequence (CBNACBS) for CBNAC, which consisted of a GCTT core sequence flanked on both sides by other frequently repeating sequences (TTGCTTANNNNNNAAG). CBNAC was able to bind to CBNACBS, which resulted in the repression of transcription in Arabidopsis protoplasts. Interestingly, the transcriptional repression mediated by CBNAC was enhanced by CaM. These results suggest that CBNAC may be a CaM-regulated transcriptional repressor in Arabidopsis.

Details

Language :
English
ISSN :
0021-9258
Volume :
282
Issue :
50
Database :
MEDLINE
Journal :
The Journal of biological chemistry
Publication Type :
Academic Journal
Accession number :
17947243
Full Text :
https://doi.org/10.1074/jbc.M705217200