|
|
||||||||
|
First published online May 13, 2005; 10.1104/pp.104.057752 Plant Physiology 138:675-685 (2005) © 2005 American Society of Plant Biologists Analysis of a Sugar Response Mutant of Arabidopsis Identified a Novel B3 Domain Protein That Functions as an Active Transcriptional Repressor1Laboratory of Biochemistry, Graduate School of Bioagricultural Science, Nagoya University, Chikusa, Nagoya 4648601, Japan (H.T., T.S., K.N.); Kazusa DNA Research Institute, Kisarazu, Chiba 2920818, Japan (D.S.); and College of Bioscience and Biotechnology, Chubu University, Kasugai, Aichi 4878501, Japan (A.M.)
A recessive mutation hsi2 of Arabidopsis (Arabidopsis thaliana) expressing luciferase (LUC) under control of a short promoter derived from a sweet potato (Ipomoea batatas) sporamin gene (Spomin::LUC) caused enhanced LUC expression under both low- and high-sugar conditions, which was not due to increased level of abscisic acid. The hsi2 mutant contained a nonsense mutation in a gene encoding a protein with B3 DNA-binding domain. HSI2 and two other Arabidopsis proteins appear to constitute a novel subfamily of B3 domain proteins distinct from ABI3, FUS3, and LEC2, which are transcription activators involved in seed development. The C-terminal part of HSI2 subfamily proteins contained a sequence similar to the ERF-associated amphiphilic repression (EAR) motif. Deletion of the C-terminal portion of HSI2 lost in the hsi2 mutant caused reduced nuclear targeting of HSI2. Null allele of HSI2 showed even higher Spomin::LUC expression than the hsi2 mutant, whereas overexpression of HSI2 reduced the LUC expression. Transient coexpression of 35S::HSI2 with Spomin::LUC in protoplasts repressed the expression of LUC activity, and deletion or mutation of the EAR motif significantly reduced the repression activity of HSI2. These results indicate that HSI2 and related proteins are B3 domain-EAR motif active transcription repressors.
1 This work was supported in part by the Research for the Future program of the Japan Society for the Promotion of Science (grant no. 00L01603) and a Grant-in-Aid for Scientific Research on Priority Areas (Molecular Mechanisms of Storage Activity in Plants) from the Ministry of Education, Culture, Sports, Science, and Technology, Japan (grant no. 12138203 to K.N. and A.M.). 2 Present address: Faculty of Agriculture, Meijo University, Tenpaku, Nagoya 4688502, Japan. Article, publication date, and citation information can be found at www.plantphysiol.org/cgi/doi/10.1104/pp.104.057752. * Corresponding author; e-mail i032011d{at}mbox.nagoya-u.ac.jp; fax 81527894094. Received December 7, 2004; returned for revision January 18, 2005; accepted January 21, 2005. This article has been cited by other articles:
|
|||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ASPB Publications | PLANT PHYSIOLOGY | THE PLANT CELL | |
|---|---|---|---|