Light-sensing via hydrogen peroxide and a peroxiredoxin.

Bodvard, Kristofer; Peeters, Ken; Roger, Friederike; Romanov, Natalie; Igbaria, Aeid; Welkenhuysen, Niek; Palais, Gaël; Reiter, Wolfgang et al. · Nat Commun · 2017

basic_science · Level V

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Abstract

Yeast lacks dedicated photoreceptors; however, blue light still causes pronounced oscillations of the transcription factor Msn2 into and out of the nucleus. Here we show that this poorly understood phenomenon is initiated by a peroxisomal oxidase, which converts light into a hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) signal that is sensed by the peroxiredoxin Tsa1 and transduced to thioredoxin, to counteract PKA-dependent Msn2 phosphorylation. Upon H<sub>2</sub>O<sub>2</sub>, the nuclear retention of PKA catalytic subunits, which contributes to delayed Msn2 nuclear concentration, is antagonized in a Tsa1-dependent manner. Conversely, peroxiredoxin hyperoxidation interrupts the H<sub>2</sub>O<sub>2</sub> signal and drives Msn2 oscillations by superimposing on PKA feedback regulation. Our data identify a mechanism by which light could be sensed in all cells lacking dedicated photoreceptors. In particular, the use of H<sub>2</sub>O<sub>2</sub> as a second messenger in signalling is common to Msn2 oscillations and to light-induced entrainment of circadian rhythms and suggests conserved roles for peroxiredoxins in endogenous rhythms.

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