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Molecular and Cellular Biology, April 2000, p. 2760-2773, Vol. 20, No. 8
Department of Molecular Biology and
Biochemistry, University of California Irvine, Irvine, California
92697-3900
Received 23 November 1999/Returned for modification 20 December
1999/Accepted 21 January 2000
Ornithine decarboxylase (ODC) of the fungus Neurospora
crassa, encoded by the spe-1 gene, catalyzes an
initial and rate-limiting step in polyamine biosynthesis and is highly
regulated by polyamines. In N. crassa, polyamines repress
the synthesis and increase the degradation of ODC protein. Changes in
the rate of ODC synthesis correlate with similar changes in the
abundance of spe-1 mRNA. We identify two sequence elements,
one in each of the 5' and 3' regions of the spe-1 gene of
N. crassa, required for this polyamine-mediated regulation.
A 5' polyamine-responsive region (5' PRR) comprises DNA sequences both
in the upstream untranscribed region and in the long 5' untranslated
region (5'-UTR) of the gene. The 5' PRR is sufficient to confer
polyamine regulation to a downstream, heterologous coding region. Use
of the
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Polyamine Regulation of Ornithine Decarboxylase
Synthesis in Neurospora crassa
and
-tubulin promoter to drive the expression of various portions
of the spe-1 transcribed region revealed a 3'
polyamine-responsive region (3' PRR) downstream of the coding region.
Neither changes in cellular polyamine status nor deletion of sequences
in the 5'-UTR alters the half-life of spe-1 mRNA. Sequences
in the spe-1 5'-UTR also impede the translation of a
heterologous coding region, and polyamine starvation partially relieves
this impediment. The results show that N. crassa uses a
unique combination of polyamine-mediated transcriptional and translational control mechanisms to regulate ODC synthesis.
*
Corresponding author. Mailing address: Department of
Molecular Biology and Biochemistry, University of California Irvine, Irvine, CA 92697-3900. Phone: (949) 824-5872. Fax: (949)
824-8551. E-mail: rhdavis{at}uci.edu.
Present address: Department of Microbiology and Immunology,
University of California San Francisco, San Francisco, CA 94143-0414.
Present address: Department of Developmental and Cell Biology,
University of California Irvine, Irvine, CA 92697-2300.
Molecular and Cellular Biology, April 2000, p. 2760-2773, Vol. 20, No. 8
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Copyright © 2000, American Society for Microbiology. All rights reserved.
This article has been cited by other articles:
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Ivanov, I. P., Loughran, G., Atkins, J. F.
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