THE PLANT CELL, Vol 2, Issue 8 805-814, Copyright © 1990 by American Society of Plant Biologists
A Light-Regulated DNA-Binding Activity Interacts with a Conserved Region of a Lemna gibba rbcS Promoter
J. S. Buzby, T. Yamada and E. M. Tobin
Department of Biology, University of California, Los Angeles, California 90024-1606
We have characterized a DNA-binding activity, designated light-regulated
nuclear factor (LRF-1), which interacted with a specific sequence located
150 nucleotides upstream from the transcription start site of a
phytochrome-regulated Lemna gibba rbcS gene (SSU5B). There was a higher
level of LRF-1 activity recovered from nuclei of light-grown plants than
from dark-treated plants. In light-grown plants given a 1-day dark
treatment, either white light or a single 2-min red illumination caused a
rapid twofold to threefold increase in this activity, suggesting that the
phytochrome system is probably involved in its regulation. The nuclear
extracts also contained an activity that bound specifically to Box II
sequences from a pea rbcS gene [Green, P.J., Yong, M.H., Cuozzo, M.,
Kano-Murakami, Y., Silverstein, P., and Chua, N.-H. (1988). EMBO J. 7,
4035-4044], but this activity was not higher in the light-grown compared
with the dark-treated plants. Comparison of about 700 base pairs upstream
from the SSU5B transcription start site with the upstream sequences of two
other Lemna rbcS genes revealed several conserved regions. One of these
regions is found upstream of rbcS genes in other species and is contained
in the sequence which was shown to interact with LRF-1.
