Polyamine Regulation of Ornithine Decarboxylase Synthesis in Neurospora crassa
AUTOR(ES)
Hoyt, Martin A.
FONTE
American Society for Microbiology
RESUMO
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 β-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.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=85492Documentos Relacionados
- Ornithine decarboxylase gene of Neurospora crassa: isolation, sequence, and polyamine-mediated regulation of its mRNA.
- Structural gene for ornithine decarboxylase in Neurospora crassa.
- Distinct roles of putrescine and spermidine in the regulation of ornithine decarboxylase in Neurospora crassa.
- Regulation of polyamine synthesis in relation to putrescine and spermidine pools in Neurospora crassa.
- Polyamine-mediated regulation of mouse ornithine decarboxylase is posttranslational.