The orphan protein bis-γ-glutamylcystine reductase joins the pyridine nucleotide disulfide reductase family

Escherichia coli as a versatile cell factory: Advances and challenges in recombinant protein production

E. coli plays a substantial role in recombinant protein production. Its importance increased with the discovery of recombinant DNA technology and the subsequent production of the first recombinant insulin in E. coli. E. coli is a widely used and cost-effective host to produce recombinant proteins. It is also noteworthy that a significant portion of the approved therapeutic proteins have been produced in this organism. Despite these advantages, it has some disadvantages, such as toxicity and lack of eukaryotic post-translational modifications that can lead to the production of misfolded, insoluble, or dysfunctional proteins. This study focused on the challenges and engineering approaches for improved expression and solubility in recombinant protein production in E. coli. In this context, solution strategies such as strain and vector selection, codon usage, mRNA stability, expression conditions, translocation to the periplasmic region and addition of fusion tags in E. coli were discussed.

Catechin Mediates Ferroptosis to Exert an Anti-Inflammatory Effect on RAW 264.7 Cells

Catechin possesses a potential anti-inflammatory activity, but its anti-inflammatory mechanism is still unclear. Herein, the analysis of network pharmacology showed that catechin might mediate ferroptosis on macrophages to exhibit a significant anti-inflammatory effect on RAW264.7. The metabolomics further indicated that catechin might influence ferroptosis by activating two pathways of cysteine and methionine metabolism and glutathione metabolism, and inhibiting the pathway of ferroptosis to promote the reduction of l-methionine-s-oxide and s-glutathionyl-l-cysteine, and the reduction and synthesis of γ-glutamylcysteine. Furthermore, related proteins (MSRA, CDR, GSR and GCL) in three metabolic pathways and ferroptosis-related proteins (GPX4 and SLC7A11) might be relevant to catechin through molecular docking. Thus, we speculate that catechin plays an anti-inflammatory effect through mediating ferroptosis on RAW264.7, which still needs further focus on the detailed molecular mechanism.

Recombinant expression of insoluble enzymes in Escherichia coli: a systematic review of experimental design and its manufacturing implications

Recombinant enzyme expression in Escherichia coli is one of the most popular methods to produce bulk concentrations of protein product. However, this method is often limited by the inadvertent formation of inclusion bodies. Our analysis systematically reviews literature from 2010 to 2021 and details the methods and strategies researchers have utilized for expression of difficult to express (DtE), industrially relevant recombinant enzymes in E. coli expression strains. Our review identifies an absence of a coherent strategy with disparate practices being used to promote solubility. We discuss the potential to approach recombinant expression systematically, with the aid of modern bioinformatics, modelling, and ‘omics’ based systems-level analysis techniques to provide a structured, holistic approach. Our analysis also identifies potential gaps in the methods used to report metadata in publications and the impact on the reproducibility and growth of the research in this field.

Molecular and functional characterization of a mitochondrial glutathione reductase homolog from redlip mullet (Liza haematocheila): Disclosing its antioxidant properties in the fish immune response mechanism

Glutathione reductase (GSHR) is a biologically important enzyme involved in the conversion of oxidized glutathione (GSSG) into its reduced form, reduced glutathione (GSH), with the catalytic activity of NADPH. Most animals and aquatic organisms, including fish, possess high levels of this enzyme system to neutralize oxidative stress in cells. The current study was conducted to broaden our knowledge of GSHR in fish by identifying a mitochondrial isoform of this enzyme (LhGSHRm) in redlip mullet, Liza haematocheila, and clarifying its structure and function. The complete open reading frame of LhGSHRm consists of 1527 base pairs, encoding 508 amino acids, with a predicted molecular weight of 55.43 kDa. Multiple sequence alignment revealed the conservation of important amino acids in this fish. Phylogenetic analysis demonstrated the closest evolutionary relationship between LhGSHRm and other fish GSHRm counterparts. In tissue distribution analysis, the highest mRNA expression of LhGSHRm was observed in the gill tissue under normal physiological conditions. Following pathogenic challenges, the LhGSHRm transcription level was upregulated in a time-dependent manner in the gill and liver tissues, which may modulate the immune reaction against pathogens. rLhGSHRm showed considerable glutathione reductase activity in an enzyme assay. Further, the biological activity of rLhGSHRm in balancing cellular oxidative stress was observed in both disk diffusion and DPPH assays. Collectively, these results support that LhGSHRm has profound effects on modulating the immune reaction in fish to sustain precise redox homeostasis.

Redox and Thiols in Archaea

Low molecular weight (LMW) thiols have many functions in bacteria and eukarya, ranging from redox homeostasis to acting as cofactors in numerous reactions, including detoxification of xenobiotic compounds. The LMW thiol, glutathione (GSH), is found in eukaryotes and many species of bacteria. Analogues of GSH include the structurally different LMW thiols: bacillithiol, mycothiol, ergothioneine, and coenzyme A. Many advances have been made in understanding the diverse and multiple functions of GSH and GSH analogues in bacteria but much less is known about distribution and functions of GSH and its analogues in archaea, which constitute the third domain of life, occupying many niches, including those in extreme environments. Archaea are able to use many energy sources and have many unique metabolic reactions and as a result are major contributors to geochemical cycles. As LMW thiols are major players in cells, this review explores the distribution of thiols and their biochemistry in archaea.

Lateral Acquisitions Repeatedly Remodel the Oxygen Detoxification Pathway in Diplomonads and Relatives

Oxygen and reactive oxygen species (ROS) are important stress factors for cells because they can oxidize many large molecules. Fornicata, a group of flagellated protists that includes diplomonads, have anaerobic metabolism but are still able to tolerate fluctuating levels of oxygen. We identified 25 protein families putatively involved in detoxification of oxygen and ROS in this group using a bioinformatics approach and propose how these interact in an oxygen detoxification pathway. These protein families were divided into a central oxygen detoxification pathway and accessory pathways for the synthesis of nonprotein thiols. We then used a phylogenetic approach to investigate the evolutionary origin of the components of this putative pathway in Diplomonadida and other Fornicata species. Our analyses suggested that the diplomonad ancestor was adapted to low-oxygen levels, was able to reduce O₂ to H₂O in a manner similar to extant diplomonads, and was able to synthesize glutathione and l-cysteine. Several genes involved in the pathway have complex evolutionary histories and have apparently been repeatedly acquired through lateral gene transfer and subsequently lost. At least seven genes were acquired independently in different Fornicata lineages, leading to evolutionary convergences. It is likely that acquiring these oxygen detoxification proteins helped anaerobic organisms (like the parasitic Giardia intestinalis) adapt to low-oxygen environments (such as the digestive tract of aerobic hosts).

DNA Repair and Photoprotection: Mechanisms of Overcoming Environmental Ultraviolet Radiation Exposure in Halophilic Archaea

Halophilic archaea push the limits of life at several extremes. In particular, they are noted for their biochemical strategies in dealing with osmotic stress, low water activity and cycles of desiccation in their hypersaline environments. Another feature common to their habitats is intense ultraviolet (UV) radiation, which is a challenge that microorganisms must overcome. The consequences of high UV exposure include DNA lesions arising directly from bond rearrangement of adjacent bipyrimidines, or indirectly from oxidative damage, which may ultimately result in mutation and cell death. As such, these microorganisms have evolved a number of strategies to navigate the threat of DNA damage, which we differentiate into two categories: DNA repair and photoprotection. Photoprotection encompasses damage avoidance strategies that serve as a "first line of defense," and in halophilic archaea include pigmentation by carotenoids, mechanisms of oxidative damage avoidance, polyploidy, and genomic signatures that make DNA less susceptible to photodamage. Photolesions that do arise are addressed by a number of DNA repair mechanisms that halophilic archaea efficiently utilize, which include photoreactivation, nucleotide excision repair, base excision repair, and homologous recombination. This review seeks to place DNA damage, repair, and photoprotection in the context of halophilic archaea and the solar radiation of their hypersaline environments. We also provide new insight into the breadth of strategies and how they may work together to produce remarkable UV-resistance for these microorganisms.

Iodotyrosine deiodinase: a unique flavoprotein present in organisms of diverse phyla

Iodide is required for thyroid hormone synthesis in mammals and other vertebrates. The role of both iodide and iodinated tyrosine derivatives is currently unknown in lower organisms, yet the presence of a key enzyme in iodide conservation, iodotyrosine deiodinase (IYD), is suggested by genomic data from a wide range of multicellular organisms as well as some bacteria. A representative set of these genes has now been expressed, and the resulting enzymes all catalyze reductive deiodination of diiodotyrosine with kcat/Km values within a single order of magnitude. This implies a physiological presence of iodotyrosines (or related halotyrosines) and a physiological role for their turnover. At least for Metazoa, IYD should provide a new marker for tracing the evolutionary development of iodinated amino acids as regulatory signals through the tree of life.