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Dynamics of a Key Conformational Transition in the Mechanism of Peroxiredoxin Sulfinylation
journal contribution
posted on 2020-02-24, 12:35 authored by Alexandre Kriznik, Marouane Libiad, Hélène Le Cordier, Samia Boukhenouna, Michel B. Toledano, Sophie Rahuel-ClermontPeroxiredoxins from
the Prx1 subfamily (Prx) are moonlighting peroxidases
that operate in peroxide signaling and are regulated by sulfinylation.
Prxs offer a major model of protein–thiol oxidative modification.
They react with H2O2 to form a sulfenic acid
intermediate that either engages into a disulfide bond, committing
the enzyme into its peroxidase cycle, or again reacts with peroxide
to produce a sulfinic acid that inactivates the enzyme. Sensitivity
to sulfinylation depends on the kinetics of these two competing reactions
and is critically influenced by a structural transition from a fully
folded (FF) to locally unfolded (LU) conformation. Analysis of the
reaction of the Tsa1 Saccharomyces cerevisiae Prx with H2O2 by Trp fluorescence-based rapid
kinetics revealed a process linked to the FF/LU transition that is
kinetically distinct from disulfide formation and suggested that sulfenate
formation facilitates local unfolding. Use of mutants of distinctive
sensitivities and of different peroxide substrates showed that sulfinylation
sensitivity is not coupled to the resolving step kinetics but depends
only on the sulfenic acid oxidation and FF-to-LU transition rate constants.
In addition, stabilization of the active site FF conformation, the
determinant of sulfinylation kinetics, is only moderately influenced
by the Prx C-terminal tail dynamics that determine the FF →
LU kinetics. From these two parameters, the relative sensitivities
of Prxs toward hyperoxidation with different substrates can be predicted,
as confirmed by in vitro and in vivo patterns of sulfinylation.
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Key Conformational Transitionvivo patternssite FF conformationdisulfide bondPrx 1 subfamilysulfinic acidPrx C-terminal tail dynamicsperoxide substratesstep kineticsmoonlighting peroxidasesTrp fluorescence-basedTsa 1 Saccharomyces cerevisiae PrxFF-to-LU transition rate constantsperoxidase cyclesulfinylation kineticsPrxs offerdisulfide formationPeroxiredoxin Sulfinylation Peroxir...sulfenic acidH 2 O 2sulfinylation sensitivitysulfenate formationsulfenic acid oxidation
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