Interaction Between GPX7 And HCF244 Regulates The Mechanism Of Response To High Light In Arabidopsis Thaliana

The maintenance of redox homeostasis is particularly important for plant growth.The intracellular redox environment can influence and regulate the function of biological macromolecules.Glutathione peroxidase(GPX)is indispensable during plant development.The main function of plant GPXs is to remove phospholipid hydroperoxides and protect cell membranes from peroxidative damage.The Arabidopsis genome encodes eight members of GPX family,the active site of them all have a Cys.Biochemical evidence has effectively demonstrated that the plant GPX family utilizes the TRX system rather than GSH as an electron donor to scavenge reactive oxygen species,and its reduction is mainly dependent on the thioredoxin system.GPXs act as hydrogen peroxide sensors and can transfer H+from the cysteine active site to a target protein with signal transduction.GPX7 plays an important role in regulating chloroplast redox signaling in high light and iron deficiency.It can be significantly expressed in response to abiotic and biotic stress factors,and it also play an important role in response to stress and environmental adaptation.Arabidopsis GPX7 is located in the chloroplast.Arabidopsis gpx7 mutants exhibit photobleaching phenotypes under high light,so it is speculated that GPX7 may be involved in regulating light-induced chloroplast redox signal transduction.Its amino acid sequence contains three cysteine residues,and has redox activity.The previous work found that the cysteine at position 108 plays an important role in the redox activity of GPX7.Oxidized GPX interacts with regulatory proteins through disulfide bonds,inducing downstream reactions to transmit redox signals.To search for downstream proteins that interact with GPX7,we conducted yeast two-hybrid screening of Arabidopsis cDNA yeast libraries.Functional analysis of screened proteins focused on candidate proteins HCF244(High Chlorophyll Fluorescence 244).HCF244 is required for translation initiation of psbA mRNA in Arabidopsis,which allows D1 to be constantly updated.It can maintain the normal function of PSII,and reduce photoinhibition of plant damage.The hcf244 mutant was a homozygous lethal mutant and only grew cotyledons and gradually yellowed and died at the seedling stage.Its function is related to the phenotype and its phenotype was similar to the gpx7 mutant phenotype under high light.In this study,the interaction between GPX7 and HCF244 was confirmed by yeast two-hybrid,luciferase complementation,and bimolecular complementation experiments.In this paper,we also showed that the contents of photosystem protein complexes in gpx7 mutants were changed under high light by immunoblot experiments,indicating that GPX7 and HCF244 may be involved in the responses high light in Arabidopsis.Therefore,we hope to further explore the mechanism of the interaction between GPX7 and HCF244,further confirm the GPX7 regulated chloroplast redox signal transduction components,and complete the transduction network of GPX7 regulation chloroplast redox signal.This paper preliminarily proves that GPX7 is involved in plant response to high light.