Regulation of interaction of the iron-responsive element binding protein with iron-responsive RNA elements.
Open Access
- 1 November 1989
- journal article
- research article
- Published by Taylor & Francis in Molecular and Cellular Biology
- Vol. 9 (11), 5055-5061
- https://doi.org/10.1128/mcb.9.11.5055
Abstract
The 5' untranslated region of the ferritin heavy-chain mRNA contains a stem-loop structure called an iron-responsive element (IRE), that is solely responsible for the iron-mediated control of ferritin translation. A 90-kilodalton protein, called the IRE binding protein (IRE-BP), binds to the IRE and acts as a translational repressor. IREs also explain the iron-dependent control of the degradation of the mRNA encoding the transferrin receptor. Scatchard analysis reveals that the IRE-BP exists in two states, each of which is able to specifically interact with the IRE. The higher-affinity state has a Kd of 10 to 30 pM, and the lower affinity state has a Kd of 2 to 5 nM. The reversible oxidation or reduction of a sulfhydryl is critical to this switching, and the reduced form is of the higher affinity while the oxidized form is of lower affinity. The in vivo rate of ferritin synthesis is correlated with the abundance of the high-affinity form of the IRE-BP. In lysates of cells treated with iron chelators, which decrease ferritin biosynthesis, a four- to fivefold increase in the binding activity is seen and this increase is entirely caused by an increase in high-affinity binding sites. In desferrioxamine-treated cells, the high-affinity form makes up about 50% of the total IRE-BP, whereas in hemin-treated cells, the high-affinity form makes up less than 1%. The total amount of IRE-BP in the cytosol of cells is the same regardless of the prior iron treatment of the cell. Furthermore, a mutated IRE is not able to interact with the IRE-BP in a high-affinity form but only at a single lower affinity Kd of 0.7 nM. Its interaction with the IRE-BP is insensitive to the sulfhydryl status of the protein.This publication has 16 references indexed in Scilit:
- Oxidation-Reduction and the Molecular Mechanism of a Regulatory RNA-Protein InteractionScience, 1989
- Translational repression in eukaryotes: partial purification and characterization of a repressor of ferritin mRNA translation.Proceedings of the National Academy of Sciences, 1988
- Binding of a Cytosolic Protein to the Iron-Responsive Element of Human Ferritin Messenger RNAScience, 1988
- Iron-Responsive Elements: Regulatory RNA Sequences That Control mRNA Levels and TranslationScience, 1988
- Identification of the Iron-Responsive Element for the Translational Regulation of Human Ferritin mRNAScience, 1987
- Iron regulates ferritin mRNA translation through a segment of its 5' untranslated region.Proceedings of the National Academy of Sciences, 1987
- A cis-acting element is necessary and sufficient for translational regulation of human ferritin expression in response to iron.Proceedings of the National Academy of Sciences, 1987
- Oligoribonucleotide synthesis using T7 RNA polymerase and synthetic DNA templatesNucleic Acids Research, 1987
- Nucleoside and nucleotide inactivation of R17 coat protein: evidence for a transient covalent RNA-protein bondBiochemistry, 1985
- LIGAND: A versatile computerized approach for characterization of ligand-binding systemsAnalytical Biochemistry, 1980