Medium‐chain dehydrogenase/reductase and aldo‐keto reductase scavenge reactive carbonyls in Synechocystis sp. PCC 6803

Abstract

Reactive carbonyls (RCs), which are inevitably produced during respiratory and photosynthetic metabolism, have the potential to cause oxidative damage to photosynthetic organisms. Previously, we proposed a scavenging model for RCs in the cyanobacterium Synechocystis sp. PCC 6803 (S. 6803). In the current study, we constructed mutants deficient in the enzymes medium-chain dehydrogenase/reductase (ΔMDR) and aldo-keto reductase (ΔAKR) to investigate their contributions to RC scavenging in vivo. We found that treatment with the lipid-derived RC acrolein causes growth inhibition and promotes greater protein carbonylation in ΔMDR, compared with the wild-type and ΔAKR. In both ΔMDR and ΔAKR, photosynthesis is severely inhibited in the presence of acrolein. These results suggest that these enzymes function as part of the scavenging systems for RCs in S. 6803 in vivo.

Responses of the chloroplast glyoxalase system to high CO2 concentrations

“…The large amount of GSH (3.5 mM) in chloroplasts [36] may play an essential role for the detoxification mechanisms of not only ROS but also MG in chloroplasts. Nevertheless, predicted increases in [CO2] and global warming potentially threaten plant growth, and may cause dicarbonyl stress, known as "plant diabetes" [37,38]. The physiological significance of scavenging systems of dicarbonyls in chloroplasts thus provides insight into the acclimation of plants to high [CO2] conditions and will aid in developing future agricultural and biotechnological strategies.…”

Cancer to Cataracts: The Mechanistic Impact of Aldo-Keto Reductases in Chronic Diseases

“…However, knocking out these genes also inhibits the organism’s ability to perform photosynthesis. This illustrates the adverse effects of enzymes that participate in multiple pathways, a direct result of their ability to catalyze various compounds [ 12 ]. The current review describes the multifaceted roles of AKRs and their implications in various chronic diseases, as discussed, are largely influenced by their ability to catalyze various compounds, a characteristic that is closely tied to their promiscuous nature.…”

Analysis of Aldo–Keto Reductase Gene Family and Their Responses to Salt, Drought, and Abscisic Acid Stresses in Medicago truncatula

“…Several AKRs have been reported to effectively detoxify cytotoxic aldehydes from abiotic-stress-related glycolysis, to improve plant stress resistance. For example, aldo-keto reductase can eliminate reactive carbonyls in Synechocystis [12]; cadmium tolerance was increased in tobacco transformed with IbAKR, which was cloned from sweet potato (Ipomoea batatas) [11]; a novel aldo-keto reductase gene, PpAKR1, from peach (Prunus persica) confers higher tolerance to salt in Arabidopsis [13]; and transgenic tobacco expressing ALDRXV4 from Xerophyta viscosa has increased resistance to drought and salt [14]. However, systematic studies of AKR family with stress resistance in a single species have not been reported.…”