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(Last modification:
29. June 2010)
S-Adenosyl-L-Methionine
Decarboxylase
(AdoMetDC)
A brief
introduction
AdoMetDC is
very important for polyamine biosynthesis, and the regulation of the expression
is extremely complex and of great interest: Translational control mechanism are very elaborate, and
worth your interest. It appears that the regulation principles are
similar in animals and plants, but there are also important differences.
There a number of
excellent reviews that give good introductions and overviews:
Bale et al., 2010;
Pegg, 2009;
Hanfrey et al., 2005;
Hanfrey et al., 2003;
Franceschetti et al., 2001.
Setup of these pages
-
This page: A brief introduction:
more...
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Our
publication on the AdoMetDC from Catharanthus roseus (1995);
an overview:
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Abstract and Introduction:
more...
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AdoMetDC cDNAs from
C. roseus: more...
-
Functional expression in E. coli and evidence that the enzyme
activity is not stimulated by putrescine:
more...
- Identification of the proenzyme processing site:
more...
- The active plant enzyme contains both subunits:
more...
- uORF
(upstream
Open
Reading
Frame):
Conserved region in the 5' leader of plant AdoMetDC mRNAs:
more...
- References
in the publication:
more...
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Our unpublished results on functional analysis
of the
uORF in C. roseus AdoMetDC: more...
-
Update on uORFs in plant
AdoMetDC: more...
-
In preparation: Update on new results from 1995 - 2010: a
brief review
- References
Our
publication
Schröder, G. and Schröder, J. (1995): cDNAs for S-adenosyl-L-methionine decarboxylase from Catharanthus roseus, heterologous expression, identification of the proenzyme processing site, evidence for the presence of both subunits in the active enzyme, and a conserved region in the 5' mRNA leader. Eur. J. Biochem. 228, 74-78.
S-Adenosyl-L-methionine decarboxylases (AdoMetDC) are pyruvoyl-dependent enzymes producing the aminopropyl group for spermidine biosynthesis, and this reaction is the rate-limiting step in polyamine biosynthesis. We characterized cDNAs from Catharanthus roseus (Madagascar periwinkle) and investigated the enzyme after heterologous expression. The largest cDNA (1864 bp) had an 5' leader of 469 bp and encoded a protein of 357 residues and 30-35% identity with mammalian AdoMetDC. The proenzyme expressed in Escherichia coli was processed into active enzyme, and the processing site was identified by site-directed mutagenesis as the second Ser in the sequence Leu-Ser-Glu-Ser-Ser. The analysis of affinity-purified proteins indicated that the active enzyme contained both subunits. The Km for S-adenosyl-L-methionine was 35-40 µM, and the enzyme activity was not stimulated by putrescine. The 5' leader of the mRNA contained start and stop codons for a polypeptide of 51 amino acids, and this region was conserved in the 5' leaders of other plant AdoMetDC mRNAs. The putative polypeptide had no similarity with the hexapeptide responsible for modulation of AdoMetDC mRNA translation in mammals. The possibility is discussed that plants evolved a different type of translational regulation.
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File History
-
29.06.2010:
Completely new setup of pages
-
October 2001: Page established
and updated
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