Stress-Induced Detoxification Enzymes in Rice Have Broad Substrate Affinity

Abstract

Reactive carbonyl compounds (RCCs) such as hydroxynonenol, malondialdehyde, acrolein, crotonaldehyde, methylglyoxal, and glyoxal accumulate at higher levels under stress in plants and damage the cell metabolic activities. Plants have evolved several detoxifying enzymes such as aldo−keto reductases (AKRs), aldehyde/alcohol dehydrogenases (ALDH/ADH), and glyoxalases. We report the phylogenetic relationship of these proteins and in silico analysis of rice-detoxifying protein structures and their substrate affinity with cofactors using docking and molecular simulation studies. Molecular simulations with nicotinamide adenine dinucleotide phosphate or glutathione cofactor docking with commonly known reactive substrates suggests that the AKRs, ALDH, and ADH proteins attain maximum conformational changes, whereas glyoxalase has fewer conformational changes with cofactor binding. Several AKRs showed a significant binding affinity with many RCCs. The rice microarray studies showed enhanced expression of many AKRs in resistant genotypes, which also showed higher affinity to RCCs, signifying their importance in managing carbonyl stress. The higher expression of AKRs is regulated by stress-responsive transcription factors (TFs) as we identified stress-specific cis-elements in their promoters. The study reports the stress-responsive nature of AKRs, their regulatory TFs, and their best RCC targets, which may be used for crop improvement programs.

Novel small molecules targeting bZIP23 TF improve stomatal conductance and photosynthesis under mild drought stress by regulating ABA

“…Because OsbZIP23 was induced under oxidative stress, we anticipate that the transcripts of target genes constans 3 ( CO3 ), aldo‐keto reductase 1 ( AKR1 ), aldehyde dehydrogenase 7 ( ALDH7 ) and pyrroline 5‐carboxylate synthase 1 ( P5CS1 ), which are known to improve tolerance [23], would be reduced when molecules are applied to seedlings. The rice seedlings were exposed to 600 µmol·m −2 ·s −1 high light conditions for 16 h in the presence of methyl viologen (MV), as well as MV along with 50 µ m of IEA and serotonin, and showed a susceptible phenotype.…”

Transcriptomic responses under combined bacterial blight and drought stress in rice reveal potential genes to improve multi-stress tolerance

“…Transcription factors like NAC, WRKY, bHLH, bZIP were induced upon drought stress and bacterial blight infection. TFs regulate many downstream target genes [ 28 – 32 ]. WRKY45 showed broad spectrum resistance and acts as a negative regulator for pathogen, salt, cold and drought stress is upregulated in combined stress [ 33 , 34 ].…”

Quantitative Proteome Profiling of a S-Nitrosoglutathione Reductase (GSNOR) Null Mutant Reveals a New Class of Enzymes Involved in Nitric Oxide Homeostasis in Plants

“…There have been no studies of specific AKR mutants in A. thaliana , and no previous work considering their potential involvement in NO homeostasis. However, AKR4C8 and 9 are highly induced upon diverse stresses, including salinity, drought, and hypoxia, while AKR4C10 and AKR4C11 are less responsive, but are expressed at certain developmental stages ( Sengupta et al, 2015 ; Vemanna et al, 2017 ; Niranjan et al, 2021 ). In addition, AKR4C8 and 9 expression, as documented in the Genevestigator database, is highly induced upon multiple biotic and abiotic stresses in comparison to the other AKRs in our proteome experiment, indicating that these two enzymes might be involved in the general stress-response in A. thaliana ( Supplementary Figure 5A ).…”

“…AKRs are widely distributed and typically reduce reactive ketones and aldehydes to the corresponding alcohols or perform the reverse oxidation reaction. The primary role of these enzymes may be to detoxify toxic compounds that arise during stress, since their expression is induced by different biotic and abiotic stresses ( Vemanna et al, 2017 ; Niranjan et al, 2021 ). Notably, while GSNOR uses NADH as the reductant, AKR activity is strictly dependent on NADPH as a source of reducing equivalents ( Fujii et al, 2021 ).…”