A novel cis-acting element in promoters of plant B-type cyclin genes activates M phase-specific transcription.
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 beta-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.
Ito
M
M
Department of Biological Sciences, Graduate School of Science, University of Tokyo, Hongo, Tokyo 113, Japan. masakito@biol.s.u-tokyo.ac.jp
Iwase
M
M
Kodama
H
H
Lavisse
P
P
Komamine
A
A
Nishihama
R
R
Machida
Y
Y
Watanabe
A
A
D001483:Base Sequence; D002453:Cell Cycle; D019926:Cyclin B / Q000235:genetics*; D018744:DNA, Plant; D016195:G2 Phase / Q000235:genetics; D018506:Gene Expression Regulation, Plant; D017343:Genes, Plant; D008156:Luciferases / Q000235:genetics; D008938:Mitosis / Q000235:genetics*; D008969:Molecular Sequence Data; D010944:Plants / Q000235:genetics; D010946:Plants, Medicinal / Q000201:enzymology / Q000235:genetics*; D011401:Promoter Regions, Genetic; D012045:Regulatory Sequences, Nucleic Acid; D012091:Repetitive Sequences, Nucleic Acid; D013045:Species Specificity; D015533:Transcriptional Activation
D019926:Cyclin B; D018744:DNA, Plant; D008156:Luciferases