Deciphering the role of DJ-1 homologs in alleviating carbonyl and oxidative stress in Arabidopsis thaliana

Abstract

The present study aims to elucidate the physiological role of plant DJ-1 homologs in Arabidopsis thaliana under various abiotic stress conditions. It seeks to provide deeper insights into the diverse functions of plant DJ-1 homologs during carbonyl and oxidative stress to preserve cellular homeostasis. Exploring Arabidopsis DJ-1D opened new avenues for studying the physiological roles of other uncharacterised Arabidopsis DJ-1 paralogs. Sequence alignment of Arabidopsis DJ-1 homologs indicated that the AtDJ-1C lacks the conserved catalytic cysteine, while AtDJ-1E, being a double-domain protein, contains only one catalytic site. These intriguing differences in the sequence suggested potential differences in their functional property, motivating further investigation of these proteins. The AtDJ-1C and AtDJ-1E proteins were purified, and their glyoxalase activity was estimated. Strikingly, AtDJ-1C and AtDJ-1E lack conventional methylglyoxalase and glyoxalase activity and do not reduce the formation of MG and GOderived advanced glycation end products (AGEs) in S. cerevisiae. Transcriptome profiling under various stress conditions showed that AtDJ-1C and AtDJ-1E were upregulated in response to heat and oxidative stress, indicating their plausible role during these stress conditions. Homozygous knockout lines of AtDJ-1C and AtDJ-1E were found to be lethal, therefore, their knockdown lines were utilised for this study. AtDJ-1C and AtDJ-1E knockdown lines displayed accumulation of ROS, reduced chlorophyll retention, and exhibited poor root elongation during thermal and oxidative stress, suggesting their crucial roles in regulating plant morphogenesis and survival during abiotic stress. Parallelly, AtDJ-1C and AtDJ-1E overexpression lines were generated, which demonstrated significantly improved health parameters in plants, such as increased root length, higher chlorophyll content, and reduced x | P a g e ROS levels in leaves. To explore how plant DJ-1 homologs are reducing ROS levels, GSH (major antioxidant) levels were estimated in yeast and plant models with the help of GSHspecific dye (monochlorobimane) and GSH estimation kit. It was observed that AtDJ-1C and AtDJ-1E modulate glutathione levels and maintain redox homeostasis in both yeast and plant models. These collective studies have significantly enhanced the understanding of DJ-1 proteins in plants, revealing their critical roles in stress responses and cellular protection. Furthermore, Arabidopsis DJ-1 homologs have emerged as promising candidates for boosting crop yields and agricultural productivity.