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A Novel cis -Acting Element in Promoters of Plant B-Type Cyclin Genes Activates M Phase–Specific Transcription

1998; Oxford University Press; Volume: 10; Issue: 3 Linguagem: Inglês

10.1105/tpc.10.3.331

1532-298X

Masaki Ito, Masayuki Iwase, Hiroaki Kodama, Philippe Lavisse, Atsushi Komamine, Ryuichi Nishihama, Yasunori Machida, Akira Watanabe,

Plant nutrient uptake and metabolism

Plant B-type cyclin genes are expressed late in the G2 and M phases of the cell cycle. Previously, we showed that the promoter of a Catharanthus roseus B-type cyclin, CYM, could direct M phase–specific transcription of a β-glucuronidase reporter gene in synchronously dividing BY2 tobacco cells. In this study, we determined the regulatory elements contained within the CYM promoter by using a luciferase reporter gene. Mutational analysis showed that a 9-bp element is essential for M phase–specific promoter activity in synchronized BY2 cells. The CYM promoter contains three other sequences similar to this element. A gain-of-function assay demonstrated that when fused to a heterologous promoter, these elements are sufficient for M phase–specific expression; therefore, we named these elements M-specific activators (MSAs). We found MSA-like sequences in B-type cyclin promoters from tobacco, soybean, and Arabidopsis as well as in the promoters of two M phase–specific genes, NACK1 and NACK2, which encode tobacco kinesin-like proteins. Thus, MSA may be a common cis-acting promoter element that controls M phase–specific expression of cell cycle–related genes in plants.