Chromatin Potentiation and ABA Activation of Phaseolin Transcription

Texas A&M Research Foundation, College Station TX

Investigators

Abstract

The long-term goal of this project is to gain new insight to mechanisms by which genes are controlled in higher organisms. Gene promoters contain information specifying the tissues in which the gene will be expressed, how much will be expressed and when it will be expressed. The gene studied here, phas, encodes the nutritional protein, phaseolin, of bean seeds. The phas promoter can be transformed (moved) into the genome of the laboratory experimental plant Arabidopsis where, as in bean, it is active during seed formation (embryogenesis) but nowhere else. Previous work has demonstrated that, if Arabidopsis is additionally (super-) transformed with a special "B3" type of transcription factor (PvALF) under the control of an inducible promoter that allows expression in leaves and other vegetative tissues, the presence of reporter substances driven by the phas promoter can be detected in leaves. Other previous studies showed that the non-expressing (silent) form of the phas promoter is protected by its organization into a unit known as a nucleosome. Thus, the controlled expression of PvALF in supertransformed Arabidopsis leaf tissues alters the repressive nucleosome structure, allowing investigation of the changes taking place as the silent phas promoter becomes active. Modification of the PvALF factor will permit an understanding of what parts of it are necessary for stimulation of the nucleosome remodeling. Simultaneously, analysis of the chemical status of the histone (basic protein) component of the nucleosome can be studied using specific antibodies to gain insight to the changes involved in its remodeling. The project will provide training opportunities to graduate and undergraduate students and has potential applications in agricultural biotechnology.