PERMEABILIZED ARABIDOPSIS PROTOPLASTS PROVIDE NEW INSIGHT INTO THE CHROMATIN STRUCTURE OF PLANT ALCOHOL-DEHYDROGENASE GENES

New data from permeabilized protoplasts have expanded our view of the 5' DNase I hypersensitive area of the Arabidopsis Adh gene derived fro m nuclei DNase I hypersensitivity analyses conducted with permeabilize d protoplasts from Arabidopsis cell cultures indicates that there are four distinct sites of hypersensitivity centered around positions - 42 5, - 325, - 200, and - 60. The hypersensitive site at - 200 coincides with an in vitro hypersensitive site created by purified transcription factors bound to a G-box element. The G-box is a functional cis eleme nt that plays a role in the signal transduction of hypoxia and other s tresses in Adh. The data presented in this paper support the notion th at G-box-related elements may also play a role in defining chromatin s tructure. The new Arabidopsis data are discussed within the context of what is known about the chromatin structures and regulation of two ot her plant Adh genes; maize Adh1 and Adh2. The chromatin oi the maize A dh; promoter is divided into a region that is constitutively hypersens itive to DNase I (- 700 to - 160) and an inducibly hypersensitive regi on (- 140 and - 40). There are several sequence elements within the hy persensitive regions bound by proteins in vivo. The anaerobic response element is the mosi well characterized and functions in the detection of hypoxia. The maize Adh2 gene promoter is constitutively hypersensi tive to DNase I, exception of a sma region that extends io include the TATA box as the gene becomes active. Several cis elements in the Adh2 promoter are bound by factors in vivo. One, at - 160, is a functional element thai acts as an activator in vascular tissue. The overall goa l of our research with the Adh genes from maize and Arabidopsis is to gain further insight into the relationships between the regulation of gene ira lion and chromatin structure in plants as ii is clear that th e necessary components that characterize regulated gene activity may n ot be Found simply by elucidating the linear sequence of nucleotides t hat lie 5' to the protein coding regions and finding proteins capable of binding the promoter in vitro. (C) 1998 Wiley-Liss, Inc.