Seed-expressed casein kinase I acts as a positive regulator of the SeFAD2 promoter via phosphorylation of the SebHLH transcription factor

Mi Jung Kim, Young Sam Go, Saet Buyl Lee, Youn Sung Kim, Jeong Sheop Shin, Myung Ki Min, Inhwan Hwang, Mi Chung Suh

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

Microsomal oleic acid desaturase (FAD2) catalyzes the first committed step of the biosynthesis of polyunsaturated fatty acids via extra-plastidial desaturation of oleic acid to linoleic acid. In the regulatory mechanism controlling seed-specific SeFAD2 expression, trans-activation of the seed-specific SeFAD2 promoter is mediated by the SebHLH transcription factor (Kim et al. in Plant Mol Biol 64:453-466, 2007). In this study, a protein interacting with SebHLH was isolated from yeast two-hybrid analysis. The protein shares approximately 80% sequence identity with other putative casein kinases and was named SeCKI (Sesame Casein Kinase I). SeCKI transcripts were predominantly expressed in developing sesame seeds and were induced approximately threefold by exogenous application of ABA. eGFP:SeCKI fusion protein was localized to the nucleus. The SeCKI protein specifically bound to SebHLH. The SeCKI protein was autophosphorylated in a calcium-independent manner and transphosphorylated the SebHLH protein. Both the SebHLH and the SeCKI genes or both the SebHLH and mutated SemCKI (K182G) genes, under the control of CaMV 35S promoter, and the GUS reporter gene driven by SeFAD2 promoter containing E- and G-Box motifs were co-expressed in developing sesame seeds. This co-expression revealed that SeCKI enhanced the SebHLH-mediated transactivation of the SeFAD2 gene promoter via phosphorylation of the SebHLH transcription factor.

Original languageEnglish
Pages (from-to)425-437
Number of pages13
JournalPlant Molecular Biology
Volume73
Issue number4
DOIs
Publication statusPublished - 2010 Jul

Keywords

  • Casein kinase I
  • FAD2
  • Linoleic acid
  • Microsomal oleic acid desaturase
  • Sesamum indicum and Transcriptional regulation

ASJC Scopus subject areas

  • Agronomy and Crop Science
  • Genetics
  • Plant Science

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