THE PLANT CELL, Vol 7, Issue 11 1923-1932, Copyright © 1995 by American Society of Plant Biologists
The Arabidopsis Adh Gene Exhibits Diverse Nucleosome Arrangements within a Small DNase I-Sensitive Domain
M. A. Vega-Palas and R. J. Fert
Horticultural Sciences Department, University of Florida, Gainesville, Florida 32611
The alcohol dehydrogenase (Adh) gene from Arabidopsis shows enhanced
sensitivity to DNase I in cells that express the gene. This generalized
sensitivity to DNase I is demarcated by position -500 on the 5[prime] side
and the end of the mRNA on the 3[prime] side. Thus, the gene defined as the
promoter and mRNA coding region corresponds very closely in size with the
gene defined as a nuclease-sensitive domain. This is a remarkably close
correspondence between a sensitive domain and a eukaryotic transcriptional
unit, because previously reported DNase I-sensitive domains include large
regions of DNA that are not transcribed. Nucleosomes are present in the
coding region of the Adh gene when it is expressed, indicating that the
transcriptional elongation process causes nucleosome disruption rather than
release of nucleosomes from the coding region. In addition, the regulatory
region contains a loosely positioned nucleosome that is separated from
adjacent nucleosomes by internucleosomic DNA segments longer than the
average linker DNA in bulk chromatin. This specific array of nucleosomes
coexists with bound transcription factors that could contribute to the
organization of the nucleosome arrangement. These results enhance our
understanding of the complex interactions among DNA, nucleosomes, and
transcription factors during gene expression in plants.