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Feedback regulation of ornithine decarboxylase expression
Author(s) -
Autelli Riccardo,
Holm Ingvar,
Heby Olle,
Persson Lo
Publication year - 1990
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(90)80060-v
Subject(s) - ornithine decarboxylase , ornithine decarboxylase antizyme , chemistry , expression (computer science) , carboxy lyases , microbiology and biotechnology , biochemistry , biology , enzyme , computer science , programming language
The rate‐controlling enzyme in polyamine synthesis, ornithine decarboxylase (ODC), is subject to feedback regulation by the polyamines at the level of translation. In the present study we used a cell‐free translation system to further investigate the mechanism by which this regulation occurs. Lysates of ODC‐overproducing cells were capable of synthesizing large amounts of ODC. The degree of initiation was poor in the lysates and the synthesis of ODC was mainly a result of continued elongation of peptide chains on pre‐initiated ribosomes. By determining the amount of ODC produced in the lysate, we obtained an estimate of the number of ribosomes that were actively translating ODC mRNA at the moment of lysis. Using this polysomal run‐off assay we demonstrated that the polyamine‐mediated regulation of ODC synthesis occurs without any change in the number of ribosomes associated with the message. This finding indicates that the polyamines exert a coordinate effect on initiation and elongation.