Arabidopsis thaliana peroxiredoxin Q is extraordinarily dynamic on the μs-ms timescale
(English)Manuscript (preprint) (Other academic)
Peroxiredoxin Q (PrxQ) isolated from Arabidopsis thaliana belongs to a family of redox enzymes called peroxiredoxins, which are thioredoxin- or glutaredoxin dependent peroxidases acting to reduce peroxides and in particular hydrogen peroxide. PrxQ cycles between an active reduced state and an inactive oxidized state during its catalytic cycle. The catalytic mechanism involves a nucleophilic attack of the catalytic cysteine on hydrogen peroxide to generate a sulfonic acid intermediate with a concerted release of a water molecule. This intermediate is subsequently relaxed by the reaction of a second cysteine, denoted as the resolving cysteine, generating an intermolecular disulphide bond to expel a second water molecule into solution. PrxQ is finally recycled to the active state by a thioredoxin dependent reduction. Previous structural studies of PrxQ homologues have provided the structural basis for the switch between reduced and oxidized conformations. Here we have performed a detailed study of the structure and dynamics of PrxQ in both the oxidized and reduced state. Reliable and experimentally validated structural models of PrxQ in both oxidation states were generated using homology based modeling. Model-free analyses of NMR spin relaxation show that PrxQ is monomeric in both oxidation states. As evident from fast R2 relaxation rates the reduced form of PrxQ undergoes unprecedented dynamics on the slow μs-ms timescale. The ground state of the conformational dynamics is likely the stably folded reduced state as implied by circular dichroism spectroscopy. We speculate that the extensive dynamics is intimately related to the catalytic function of PrxQ.
activity, circular dichroism, dynamics, enzyme, NMR
Medical Biotechnology (with a focus on Cell Biology (including Stem Cell Biology), Molecular Biology, Microbiology, Biochemistry or Biopharmacy) Biophysics
Research subject Biochemistry; Physical Chemistry
IdentifiersURN: urn:nbn:se:umu:diva-36751OAI: oai:DiVA.org:umu-36751DiVA: diva2:356108