Ectoine and hydroxyectoine inhibit thermal-induced aggregation and increase thermostability of recombinant human interferon Alfa2b

Ectoine enhances recombinant antibody production in Chinese hamster ovary cells by promoting cell cycle arrest

Chinese hamster ovary (CHO) cells represent the most preferential host cell system for therapeutic monoclonal antibody (mAb) production. Enhancing mAb production in CHO cells can be achieved by adding chemical compounds that regulate the cell cycle and cell survival pathways. This study investigated the impact of ectoine supplementation on mAb production in CHO cells. The results showed that adding ectoine at a concentration of 100 mM on the 3rd day of cultivation improved mAb production by improving cell viability and extending the culture duration. RNA sequencing analysis revealed differentially expressed genes associated with cell cycle regulation, cell proliferation, and cellular homeostasis, in particular promotion of cell cycle arrest, which was then confirmed by flow cytometry analysis. Ectoine-treated CHO cells exhibited an increase in the number of cells in the G0/G1 phase. In addition, the cell diameter was also increased. These findings support the hypothesis that ectoine enhances mAb production in CHO cells through mechanisms involving cell cycle arrest and cellular homeostasis. Overall, this study highlights the potential of ectoine as a promising supplementation strategy to enhance mAb production not only in CHO cells but also in other cell lines.

Biotechnological production of ectoine: current status and prospects

Ectoine is an important natural secondary metabolite in halophilic microorganisms. It protects cells against environmental stressors, such as salinity, freezing, drying, and high temperatures. Ectoine is widely used in medical, cosmetic, and other industries. Due to the commercial market demand of ectoine, halophilic microorganisms are the primary method for producing ectoine, which is produced using the industrial fermentation process "bacterial milking." The method has some limitations, such as the high salt concentration fermentation, which is highly corrosive to the equipment, and this also increases the difficulty of downstream purification and causes high production costs. The ectoine synthesis gene cluster has been successfully heterologously expressed in industrial microorganisms, and the yield of ectoine was significantly increased and the cost was reduced. This review aims to summarize and update microbial production of ectoine using different microorganisms, environments, and metabolic engineering and fermentation strategies and provides important reference for the development and application of ectoine.

Methanotrophs as a reservoir for bioactive secondary metabolites: Pitfalls, insights and promises

Methanotrophs are potent natural producers of several bioactive secondary metabolites (SMs) including isoprenoids, polymers, peptides, and vitamins. Cryptic biosynthetic gene clusters identified from these microbes via genome mining hinted at the vast and hidden SM biosynthetic potential of these microbes. Central carbon metabolism in methanotrophs offers rare pathway intermediate pools that could be further diversified using advanced synthetic biology tools to produce valuable SMs; for example, plant polyketides, rare carotenoids, and fatty acid-derived SMs. Recent advances in pathway reconstruction and production of isoprenoids, squalene, ectoine, polyhydroxyalkanoate copolymer, cadaverine, indigo, and shinorine serve as proof-of-concept. This review provides theoretical guidance for developing methanotrophs as microbial chassis for high-value SMs. We summarize the distinct secondary metabolic potentials of type I and type II methanotrophs, with specific attention to products relevant to biomedical applications. This review also includes native and non-native SMs from methanotrophs, their therapeutic potential, strategies to induce silent biosynthetic gene clusters, and challenges.

Disclosing the Potential of Fluorinated Ionic Liquids as Interferon-Alpha 2b Delivery Systems

Interferon-alpha 2b (IFN-α 2b) is a therapeutic protein used for the treatment of cancer, viral infections, and auto-immune diseases. Its application is hindered by a low bioavailability and instability in the bloodstream, and the search for new strategies for a target delivery and stabilization of IFN-α 2b to improve its therapeutic efficacy is crucial. Fluorinated ionic liquids (FILs) are promising biomaterials that: (i) can form self-assembled structures; (ii) have complete miscibility in water; and (iii) can be designed to have reduced toxicity. The influence of IFN-α 2b in the aggregation behaviour of FILs and the interactions between them were investigated through conductivity and surface tension measurements, and using electron microscopic and spectroscopy techniques to study FILs feasibility as an interferon-alpha 2b delivery system. The results show that the presence of IFN-α 2b influences the aggregation behaviour of FILs and that strong interaction between the two compounds occurs. The protein might not be fully encapsulated by FILs. However, the FIL can be tailored in the future to carry IFN-α 2b by the formation of a conjugate, which prevents the aggregation of this protein. This work constitutes a first step toward the design and development of FIL-based IFN-α 2b delivery systems.

Ectoine and Hydroxyectoine Stabilize Antibodies in Spray-Dried Formulations at Elevated Temperature and during a Freeze/Thaw Process

Maintenance of protein stability during manufacture, storage, and delivery is necessary for the successful development of a drug product. Herein, the utility of two compatible solutes-ectoine and hydroxyectoine-in stabilizing a model protein labeled Fab2 has been investigated. Specifically, the performance of ectoine and hydroxyectoine in stabilizing Fab2 in a spray-dried formulation at elevated temperature and after multiple freeze/thaw cycles has been compared with the performance of a formulation containing trehalose and a formulation containing no excipient as controls. In the solid state at 90 and 37 °C and in freeze concentrate systems, ectoine and hydroxyectoine suppress protein aggregation. Like trehalose, hydroxyectoine also limits N-terminal pyroglutamate formation in Fab2 in the solid state. The extent of protein stabilization is dependent on the excipient concentration in the formulation, but at a 1:1 excipient to protein mass ratio, hydroxyectoine is better than trehalose in stabilizing Fab2. The results presented here suggest that ectoine and hydroxyectoine are effective excipients for stabilizing therapeutic antibodies.

Hydroxyectoine protects Mn-depleted photosystem II against photoinhibition acting as a source of electrons

In the present study, we have investigated the effect of hydroxyectoine (Ect-OH), a heterocyclic amino acid, on oxygen evolution in photosystem II (PS II) membrane fragments and on photoinhibition of Mn-depleted PS II (apo-WOC-PS II) preparations. The degree of photoinhibition of apo-WOC-PS II preparations was estimated by the loss of the capability of exogenous electron donor (sodium ascorbate) to restore the amplitude of light-induced changes of chlorophyll fluorescence yield (∆F). It was found that Ect-OH (i) stimulates the oxygen-evolving activity of PS II, (ii) accelerates the electron transfer from exogenous electron donors (K₄[Fe(CN)₆], DPC, TMPD, Fe²⁺, and Mn²⁺) to the reaction center of apo-WOC-PS II, (iii) enhances the protective effect of exogenous electron donors against donor-side photoinhibition of apo-WOC-PS II preparations. It is assumed that Ect-OH can serve as an artificial electron donor for apo-WOC-PS II, which does not directly interact with either the donor or acceptor side of the reaction center. We suggest that the protein conformation in the presence of Ect-OH, which affects the extent of hydration, becomes favorable for accepting electrons from exogenous donors. To our knowledge, this is the first study dealing with redox activity of Ect-OH towards photosynthetic pigment-protein complexes.

Stabilization of bovine lactoperoxidase in the presence of ectoine

Lactoperoxidase (LPO) is a heme peroxidase with various applications in industry and medicine. In this study, the effects of ectoine, as a compatible solute, on the structure, thermal stability, thermodynamic parameters, activity, and stability of LPO have been investigated. The results showed that the catalytic activity of LPO was improved by increasing ectoine concentration. The UV-visible absorption spectroscopy and FTIR spectra studies indicated that ectoine could bind to the LPO spontaneously. Moreover, ectoine increased the enzyme Tm and Gibbs free energy. The fluorescence measurements showed that LPO fluorescence was quenched in the presence of ectoine. The quenching mechanism was probably a static quenching by forming a ground state complex. The thermodynamic parameters indicated that hydrogen bonding and Vander Waals forces played a key role in the LPO-ectoine interaction process. The findings suggest that ectoine could be used as a lactoperoxidase stabilizing agent for industrial or medical purposes.