Oxidative regulation of chloroplast enzymes by thioredoxin and thioredoxin-like proteins in Arabidopsis thaliana

Thioredoxin (Trx) is a protein that mediates the reducing power transfer from the photosynthetic electron transport system to target enzymes in chloroplasts and regulates their activities. Redox regulation governed by Trx is a system that is central to the adaptation of various chloroplast functions to the ever-changing light environment. However, the factors involved in the opposite reaction (i.e., the oxidation of various enzymes) have yet to be revealed. Recently, it has been suggested that Trx and Trx-like proteins could oxidize Trx-targeted proteins in vitro. To elucidate the in vivo function of these proteins as oxidation factors, we generated mutant plant lines deficient in Trx or Trx-like proteins and studied how the proteins are involved in oxidative regulation in chloroplasts. We found that f-type Trx and two types of Trx-like proteins, Trx-like 2 and atypical Cys His-rich Trx (ACHT), seemed to serve as oxidation factors for Trx-targeted proteins, such as fructose-1,6-bisphosphatase, Rubisco activase, and the γ-subunit of ATP synthase. In addition, ACHT was found to be involved in regulating nonphotochemical quenching, which is the mechanism underlying the thermal dissipation of excess light energy. Overall, these results indicate that Trx and Trx-like proteins regulate chloroplast functions in concert by controlling the redox state of various photosynthesis-related proteins in vivo.

Oxidative regulation of the mechanical strength of a C–S bond

The mechanical strength of individual polymer chains is believed to underlie a number of performance metrics in bulk materials, including adhesion and fracture toughness.

Can oxidative stress markers help define stroke prognosis?

Objective: To identify which oxidative stress markers can influence early stroke prognosis. Methodology: This is a systematic review carried out in two databases, PubMed and Web of Science, from November to December 2018. Two blinded, independent researchers probed the databases and gleaned descriptors indexed on both sites. “Markers”, “oxidative stress” AND “stroke” were the terms singled out for this study. The inclusion criteria were: the articles needed to have been published in English from 2013 to 2018, as well as include descriptors either in the title or in the abstract, and involve clinical trials with samples composed of stroke survivors. The exclusion criteria were: research involving animal experimentation; duplicate publications; articles without a clear methodology; articles that chiefly addressed any disease other than stroke, and those that were not available in full. Results: This review identified TBARS, catalase, nitric oxide (NO), Thiois, C-reactive protein and SOD as the most recurrent oxidative regulation markers in stroke survivors. These findings may direct new research toward obtaining early prognoses, and therefore enable more accurate decision-making. thus minimizing the costs and time related to the patient rehabilitation process.

GSTO2 Isoforms Participate in the Oxidative Regulation of the Plasmalemma in Eutherian Spermatozoa during Capacitation

In addition to perinuclear theca anchored glutathione-s-transferase omega 2 (GSTO2), whose function is to participate in sperm nuclear decondensation during fertilization (Biol Reprod. 2019, 101:368–376), we herein provide evidence that GSTO2 is acquired on the sperm plasmalemma during epididymal maturation. This novel membrane localization was reinforced by the isolation and identification of biotin-conjugated surface proteins from ejaculated and capacitated boar and mouse spermatozoa, prompting us to hypothesize that GSTO2 has an oxidative/reductive role in regulating sperm function during capacitation. Utilizing an inhibitor specific to the active site of GSTO2 in spermatozoa, inhibition of this enzyme led to a decrease in tyrosine phosphorylation late in the capacitation process, followed by an expected decrease in acrosome exocytosis and motility. These changes were accompanied by an increase in reactive oxygen species (ROS) levels and membrane lipid peroxidation and culminated in a significant decrease in the percentage of oocytes successfully penetrated by sperm during in vitro fertilization. We conclude that GSTO2 participates in the regulation of sperm function during capacitation, most likely through protection against oxidative stress on the sperm surface.

Proteins Involved in Energy Metabolism and Oxidative Regulation Associated with Genotypic Variations in Drought Tolerance for Tall Fescue

Protein metabolism plays an important role in plant adaptation to drought stress. The objective of this study was to identify drought-responsive proteins associated with differential drought tolerance for a tolerant genotype (RU9) and a sensitive genotype (RU18) of tall fescue (Lolium arundinacea). Plants of both genotypes were grown under well-watered conditions or subjected to drought stress by withholding irrigation for 12 days in a growth chamber controlled at the optimal growth temperatures of 23/18 °C (day/night). Physiological analysis demonstrated that RU9 was relatively more drought tolerant than RU18, as shown by the higher leaf net photosynthetic rate (Pn) and photochemical efficiency at 12 days of drought treatment. Differentially expressed proteins between RU9 and RU18 exposed to drought stress were identified by two-dimensional electrophoresis and mass spectrometry (MS). Several proteins [photosystem I reaction center subunit II, Rubisco small subunit, and Glyceraldehyde-3-phosphate dehydrogenase (GADPH)] in photosynthesis, respiration, or oxidative regulation exhibited higher abundance in RU9 than RU18 under drought stress. These results suggested the critical importance of energy and oxidative metabolism in tall fescue adaptation to drought stress. Those abundant proteins in the drought-tolerant genotype could be used as biomarkers or developed to molecular markers to develop elite drought-tolerant germplasm in tall fescue and other cool-season perennial grass species.

The Double-Edged Sword in Pathogenic Trypanosomatids: The Pivotal Role of Mitochondria in Oxidative Stress and Bioenergetics

The pathogenic trypanosomatidsTrypanosoma brucei,Trypanosoma cruzi, andLeishmaniaspp. are the causative agents of African trypanosomiasis, Chagas disease, and leishmaniasis, respectively. These diseases are considered to be neglected tropical illnesses that persist under conditions of poverty and are concentrated in impoverished populations in the developing world. Novel efficient and nontoxic drugs are urgently needed as substitutes for the currently limited chemotherapy. Trypanosomatids display a single mitochondrion with several peculiar features, such as the presence of different energetic and antioxidant enzymes and a specific arrangement of mitochondrial DNA (kinetoplast DNA). Due to mitochondrial differences between mammals and trypanosomatids, this organelle is an excellent candidate for drug intervention. Additionally, during trypanosomatids’ life cycle, the shape and functional plasticity of their single mitochondrion undergo profound alterations, reflecting adaptation to different environments. In an uncoupling situation, the organelle produces high amounts of reactive oxygen species. However, these species role in parasite biology is still controversial, involving parasite death, cell signalling, or even proliferation. Novel perspectives on trypanosomatid-targeting chemotherapy could be developed based on better comprehension of mitochondrial oxidative regulation processes.