Present address: Graduate School of Biological Sciences, Nara Institute of Science and Technology, Ikoma 630–0101, Japan.
Identification of three kinds of mutually related composite elements conferring S phase-specific transcriptional activation
Article first published online: 5 JAN 2002
The Plant Journal
Volume 18, Issue 6, pages 611–623, June 1999
How to Cite
Taoka, K.-i., Kaya, H., Nakayama, T., Araki, T., Meshi, T. and Iwabuchi, M. (1999), Identification of three kinds of mutually related composite elements conferring S phase-specific transcriptional activation. The Plant Journal, 18: 611–623. doi: 10.1046/j.1365-313x.1999.00486.x
- Issue published online: 5 JAN 2002
- Article first published online: 5 JAN 2002
- Received 23 December 1998; revised 19 April 1999; accepted 26 April 1999.
Conservation of the Oct motif (CGCGGATC) is a remarkable feature of plant histone gene promoters. Many of the Oct motifs are paired with a distinct motif, Hex, TCA or CCAAT-box, constituting the type I element (CCACGTCANCGATCCGCG), type II element (TCACGCGGATC) and type III element (GATCCGCG-N14-ACCAATCA). To clarify the roles of these Oct-containing composite elements (OCEs) in cell cycle-dependent and tissue-specific expression, we performed gain-of-function experiments with transgenic tobacco cell lines and plants harboring a derivative of the 35S core promoter/β-glucuronidase fusion gene in which three or four copies of an OCE had been placed upstream. Although their activities were slightly different, results showed that each of the three types of OCEs could confer the ability to direct S phase-specific expression on a heterologous promoter. In transgenic plants, the type I and III elements exhibited a similar activity, directing expression in meristematic tissues, whereas the activity of the type II element appeared to be restricted to young cotyledons and maturating guard cells. Mutational analyses demonstrated that the co-operation of Oct with another module (Hex, TCA or CCAAT-box) was absolutely required for both temporal and spatial regulation. Thus, OCEs play a pivotal role in regulation of the expression of plant histone genes.