Novel inducible repressible gene expression systems

This chapter discusses the novel inducible/repressible gene-expression systems. It describes a method that allows the regulated expression of a transgene upon a specific chemical stimulus. The control mechanism works at the level of the initiation of mRNA synthesis. Transcriptional regulation is generally mediated through the interaction of proteins with certain DNA sequences within a promoter. Plant promoters—like other eukaryotic promoters—contain two functionally distinct classes of elements that affect transcription. The TATA motif, which is typically located 30 nucleotides upstream of the transcription start site, makes up the first class. The second class of promoter elements is composed of small DNA sequences recognized specifically by DNA-binding proteins that synergistically regulate the activity of the transcription initiation complex. Proteins that activate transcription via these elements are modular, containing a DNA binding domain and an activation domain. An alternative approach is to place the general plant transcription machinery under the control of regulatory elements taken from other organisms, which respond to signals usually not encountered by plants. © 1995, Academic Press, Inc.