J Biol Chem, Vol. 274, Issue 29, 20384-20390, July 16, 1999
Identification of cis-Regulating Elements and
trans-Acting Factors Regulating the Expression of the Gene
Encoding the Small Subunit of Ribonucleotide Reductase in
Dictyostelium discoideum
Claire
Bonfils
,
Pascale
Gaudet¶
, and
Adrian
Tsang
¶
From the
Department of Biology, ¶ Department of
Chemistry and Biochemistry, and
Centre for Structural and
Functional Genomics, Concordia University,
Montreal, Quebec H3G 1M8, Canada
We have examined the promoter of
rnrB, the gene encoding the small subunit of ribonucleotide
reductase of Dictyostelium discoideum, using
lacZ as a reporter gene. Deletion analysis showed that
expression of this gene in vegetative cells involves an A/T-rich
element, whereas its expression in prespore cells during development
requires a region encompassing two G/C-rich elements, designated box A and box B. Removal of boxes A and B results in very low level of
activity. When either box A or box B is deleted, prestalk cells adjacent to the prespore zone also express
-galactosidase. The behavior of these cis-regulatory elements implies that the
mechanism regulating the prespore-specific expression of
rnrB is different from that regulating other known prespore genes.
We have used electrophoretic mobility shift assays to identify factors
that interact with box A and box B. Box A interacts with a factor that
is found in the nuclear fraction. While box B interacts with a factor
that is present in the cytosolic fraction throughout growth and
development, its presence in the nuclear fraction is developmentally
regulated. Results from competition assays suggest that both box A and
box B interact with transcriptional activators that have not been
characterized previously.
Copyright © 1999 by The American Society for Biochemistry and Molecular Biology, Inc.