THE PLANT CELL, Vol 1, Issue 11 1069-1077, Copyright © 1989 by American Society of Plant Biologists
Binding of a Pea Nuclear Protein to Promoters of Certain Photoregulated Genes Is Modulated by Phosphorylation
N. Datta and A. R. Cashmore
Plant Science Institute, Department of Biology, University of Pennsylvania, Philadelphia, Pennsylvania 19104
There have been numerous recent reports documenting phosphorylation of
DNA-binding proteins [Montminy and Bilezikjian (1987); Sorger, Lewis, and
Pelham (1987); Hoeffler, Kovelman, and Roeder (1988); Jones et al. (1988);
Prywes et al. (1988); Sorger and Pelham (1988); Yamamoto et al. (1988)],
and the transcriptional regulatory activity of at least one of these
proteins appears to be modulated by this modification [Montminy and
Bilezikjian (1987); Yamamoto et al. (1988)]. We report here on a plant
nuclear protein, the DNA-binding activity of which is strongly affected by
phosphorylation. This protein, AT-1, binds to specific AT-rich elements
(the AT-1 box) within promoters of certain nuclear genes encoding the small
subunit of ribulose-1,5-bisphosphate carboxylase and the polypeptide
components of the light-harvesting chlorophyll a/b protein complex. A
consensus sequence of AATATTTTTATT was derived for the AT-1 box. We
demonstrate that the DNA-binding ability of AT-1, from nuclear extracts of
pea, can be reversibly modulated by phosphorylation. AT-1 is active in the
nonphosphorylated form and loses all DNA-binding ability as a result of
phosphorylation. The kinase that phosphorylates AT-1 uses both Mg-ATP and
Mg-GTP as a substrate and is inhibited by heparin and spermine, indicative
of an NII-type casein kinase.
