Light-sensing via hydrogen peroxide and a peroxiredoxin

Area of Science:

• Cellular Biology
• Biochemistry
• Signaling Pathways

Background:

• Yeast lacks dedicated photoreceptors, yet exhibits Msn2 transcription factor oscillations in response to blue light.
• The precise mechanism underlying light-induced Msn2 oscillations in yeast remains poorly understood.

Purpose of the Study:

• To elucidate the molecular mechanism by which blue light induces Msn2 oscillations in yeast.
• To identify the signaling pathway initiated by light perception in the absence of photoreceptors.

Main Methods:

• Investigated the role of peroxisomal oxidases and hydrogen peroxide (H2O2) in light signaling.
• Utilized genetic and biochemical approaches to study peroxiredoxin Tsa1 and thioredoxin function.
• Analyzed the interplay between H2O2 signaling, Protein Kinase A (PKA)-dependent phosphorylation, and Msn2 nuclear localization.

Main Results:

• A peroxisomal oxidase converts light into a H2O2 signal.
• Peroxiredoxin Tsa1 senses H2O2, counteracting PKA-dependent Msn2 phosphorylation.
• Tsa1 antagonizes PKA subunit nuclear retention, modulating Msn2 nuclear concentration.
• Peroxiredoxin hyperoxidation disrupts the H2O2 signal, driving Msn2 oscillations.

Conclusions:

• Identified a novel light-sensing mechanism in yeast involving H2O2 as a second messenger.
• Demonstrated conserved roles for peroxiredoxins in mediating light responses and potentially endogenous rhythms.
• This pathway provides a model for light perception in cells lacking specialized photoreceptors.