A safety catch for ornithine decarboxylase degradation
Authors:Christof Taxis
doi: 10.15698/mic2015.06.210
Volume 2, pp. 174 to 177, published 27/05/2015.
Department of Biology/Genetics, Philipps-University Marburg, Germany.
Keywords:
degron, feedback inhibition, ornithine decarboxylase, polyamines, proteasome, protein degradation, ubiquitin-independent degradation
Corresponding Author(s):
Conflict of interest statement:
The author declares no conflict of interest.
Please cite this article as:
Christof Taxis (2015). A safety catch for ornithine decarboxylase degradation. Microbial Cell 2(6): 174-177.
© 2015 Taxis. This is an open-access article released under the terms of the Creative Commons Attribution (CC BY) license, which allows the unrestricted use, distribution, and reproduction in any medium, provided the original author and source are acknowledged.
Abstract:
Feedback inhibition is a common mechanism to adjust the activity of an enzyme in accordance with the abundance of a product. The enzyme catalyzing the initial, committing step of a biosynthesis cascade is subject to negative feedback by the end-product. This kind of regulation is frequent in all cell types to regulate biosynthesis of numerous metabolites; a classical textbook example is the serine biosynthesis pathway (Berg et al., Biochemistry 5th edition 2002). The first irreversible reaction (A->B) is regulated by the end-product (Z) of the biosynthesis pathway (Figure 1A). In E. coli, serine inhibits 3-phosphoglycerate dehydrogenase activity by binding to a regulatory site within the enzyme. Thus, the enzyme is inactive whenever serine is in excess. Negative feedback can be implemented also in a different way: the end-product influences abundance and activity of a protein-based inhibitor, which regulates the enzyme catalyzing the initial step, to control the flux through the biosynthesis pathway. An example for this kind of feedback inhibition in eukaryotic cells is the regulation of polyamine-levels by feedback inhibition of ornithine decarboxylase (ODC) (Figure 1B), which is rate-limiting for the synthesis of the aliphatic polyamines putrescine, spermidine and spermine (Coffino, Nat Rev Mol Cell Biol 2001; Wallace et al., Biochem J 2003).