LIGHT-INDUCED TRANSCRIPTIONAL REPRESSION OF THE PEA AS1 GENE - IDENTIFICATION OF CIS-ELEMENTS AND TRANSFACTORS

Citation
N. Ngai et al., LIGHT-INDUCED TRANSCRIPTIONAL REPRESSION OF THE PEA AS1 GENE - IDENTIFICATION OF CIS-ELEMENTS AND TRANSFACTORS, Plant journal, 12(5), 1997, pp. 1021-1034
Citations number
39
Journal title
ISSN journal
09607412
Volume
12
Issue
5
Year of publication
1997
Pages
1021 - 1034
Database
ISI
SICI code
0960-7412(1997)12:5<1021:LTROTP>2.0.ZU;2-S
Abstract
Here, we examine the cis-elements and trans-factors affecting the expr ession of asparagine synthetase (AS) genes whose transcription is nega tively regulated by light. The promoters for the AS1 and AS2 genes of pea were isolated, sequenced, and functionally dissected for their abi lity to confer regulated expression to the GUS reporter gene in transg enic tobacco. Histochemical analysis of transgenic plants demonstrated that the AS1 and AS2 promoters show identical patterns of cell-specif ic expression. The more highly active AS1 promoter was further demonst rated to confer negative light-regulation to the GUS gene in transgeni c tobacco. Deletion analysis and gain-of-function experiments showed t hat 124 bp of the AS1 promoter was sufficient to confer light-activate d repression to a heterologous promoter. Potential conserved transcrip tion regulatory elements, Box B, Box C, and Box C' within this region were shown to bind to nuclear proteins by gel shift analysis. A light- specific DNA:protein interaction was detected with Box B. The nuclear factors that bind to Box C and C' elements of AS1 are competed by a pu tative repressor element 'RE1' defined previously in the oat phytochro me gene whose transcription is also repressed by light. The Box B and C/C'-Box/RE1-binding factors were found in nuclear extracts of tobacco , pea, and Arabidopsis and may therefore be universal factors involved in light-activated transcriptional repression.