Ribonucleotide reductase (RNR) catalyses the rate limiting step of DNA synthesis utilising a mechanism that requires a tyrosyl radical. We have previously shown that superoxide can quench protein tyrosyl radicals in vitro, either by oxidative addition, or reduction of the radical to tyrosine. Here, we observe that Saccharomyces cerevisiae strains lacking either copper-zinc SOD (SOD1) or manganese SOD (SOD2) had decreased RNR activity compared to SOD competent yeast. When superoxide production was increased by treatment with paraquat, RNR activity was further decreased, with yeast lacking SOD1 being the most sensitive. The growth of yeast lacking SOD1 was also the most sensitive to paraquat treatment. Using expressed recombinant RNR, superoxide addition was not detectable using mass-spectrometry. This suggests that oxidative addition is not the major route of inhibition in our system, but does not rule out reduction by superoxide as a possible mechanism. Our results demonstrate that protection of RNR from inactivation by superoxide is an important function of SOD, particularly cytoplasmic SOD1.
Pharmacology, Toxicology and Pharmaceutical Science
1
4%
Other
0
0%
Unknown
8
30%
Attention Score in Context
Attention Score in Context
This research output has an Altmetric Attention Score of 2. This is our high-level measure of the quality and quantity of online attention that it has received. This Attention Score, as well as the ranking and number of research outputs shown below, was calculated when the research output was last mentioned on 07 February 2018.
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#24,100,909
of 34,376,207 outputs
Outputs from Free Radical Biology & Medicine
#5,003
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Outputs of similar age
#331,368
of 496,992 outputs
Outputs of similar age from Free Radical Biology & Medicine
#50
of 79 outputs
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