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Mouse ribonucleotide reductase control: influence of substrate binding upon interactions with allosteric effectors
1Department of Biochemistry and Biophysics, Oregon State University, Corvallis 97331-7305, USA.
The Journal of Biological Chemistry
|December 2, 2000
Summary
Mouse ribonucleotide reductase is regulated by ADP, impacting GDP reduction, unlike the vaccinia virus enzyme. This suggests a key role for ribonucleotide reductase in cellular regulation and viral DNA replication.
Area of Science:
- Biochemistry
- Molecular Biology
- Enzymology
Background:
- Ribonucleotide reductase (RNR) is essential for DNA synthesis.
- The vaccinia virus RNR has been used as a model for mammalian RNR.
- Previous studies showed ADP inhibits its own reduction by vaccinia RNR.
Purpose of the Study:
- To investigate the regulatory properties of mouse RNR using a four-substrate assay.
- To compare mouse RNR regulation with that of vaccinia virus RNR.
- To understand the interaction between substrate binding and allosteric regulation in RNR.
Main Methods:
- Developed a simultaneous four-substrate assay for ADP, CDP, GDP, and UDP reduction.
- Analyzed recombinant mouse RNR and hybrid mouse-vaccinia RNR constructs.
- Studied the effects of substrates and allosteric modifiers on RNR activity.
Main Results:
- Mouse RNR exhibits allosteric control similar to single-substrate assays but with higher sensitivity.
- Mouse RNR shows increased activity with UDP and significant ADP inhibition of GDP reduction.
- Nucleotide diphosphate binding at the catalytic site influences effector binding at the specificity site.
- A mouse R1/vaccinia R2 hybrid RNR displayed unexpectedly high activity.
Conclusions:
- Mouse RNR possesses distinct regulatory features compared to vaccinia RNR, including broader ADP inhibition.
- Substrate binding significantly impacts allosteric regulation in mouse RNR.
- Hybrid RNR studies provide insights into viral RNR function and its limited impact on viral replication.
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