Pathogenic bacterial membrane proteins (MPs) are a class of vaccine and antibiotic development targets with widespread clinical application. However, the inherent hydrophobicity of MPs poses a ...challenge to fold correctly in living cells. Herein, we present a comprehensive method to improve the soluble form of MP antigen by rationally designing multi‐epitope chimeric antigen (ChA) and screening two classes of protein‐assisting folding element. The study uses a homologous protein antigen as a functional scaffold to generate a ChA possessing four epitopes from transferrin‐binding protein A of Glaesserella parasuis. Our engineered strain, which co‐expresses P17 tagged‐ChA and endogenous chaperones groEL‐ES, yields a 0.346 g/L highly soluble ChA with the property of HPS‐positive serum reaction. Moreover, the protein titer of ChA reaches 4.27 g/L with >90% soluble proportion in 5‐L bioreactor, which is the highest titer reported so far. The results highlight a timely approach to design and improve the soluble expression of MP antigen in industrially viable applications.
Chen et al. present a novel strategy to improve soluble form of multi‐epitope chimeric antigen via computer‐assisted strategy and folding elements is developed in this study, which provides potential applications to achieve high soluble expression and productivity of membrane protein antigen against Glaesserella parasuis. By using this strategy, an industrial E. coli recombinant strain capable of efficiently expressing subunit vaccine candidate was obtained.
Keratin is widely recognized as a high‐quality renewable protein resource for biomedical applications. Despite their extensive existence, keratin resources such as feathers, wool, and hair exhibit ...high stability and mechanical properties because of their high disulfide bond content. Consequently, keratin extraction is challenging and its application is greatly hindered. In this work, a biological extraction strategy is proposed for the preparation of bioactive keratin and the fabrication of self‐assembled keratin hydrogels (KHs). Based on moderate and controlled hydrolysis by keratinase, keratin with a high molecular weight of approximately 45 and 28 kDa that retain its intrinsic bioactivities is obtained. The keratin products show excellent ability to promote cell growth and migration and are conferred with significant antioxidant ability because of their intrinsically high cysteine content. In addition, without the presence of any cross‐linking agent, the extracted keratin can self‐assemble into injectable hydrogels. The KHs exhibit a porous network structure and 3D culture ability, showing potential in promoting wound healing. This enzyme‐driven keratin extraction strategy opens up a new approach for the preparation of keratin that can self‐assemble into injectable hydrogels for biomedical engineering.
This work not only provided a novel ecofriendly method for the extraction of bioactive keratins from wool wastes based on the moderate and controlled hydrolysis of keratinase, but also prepared self‐assembled keratin hydrogels for promoting wound repair. It can help dispose keratin solid contaminants and achieve their high value by recycling as biomaterials.
Developing bifunctional efficient and durable non-noble electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is highly desirable and challenging for overall ...water splitting. Herein, Co–Mn carbonate hydroxide (CoMnCH) nanosheet arrays with controllable morphology and composition were developed on nickel foam (NF) as such a bifunctional electrocatalyst. It is discovered that Mn doping in CoCH can simultaneously modulate the nanosheet morphology to significantly increase the electrochemical active surface area for exposing more accessible active sites and tune the electronic structure of Co center to effectively boost its intrinsic activity. As a result, the optimized Co1Mn1CH/NF electrode exhibits unprecedented OER activity with an ultralow overpotential of 294 mV at 30 mA cm–2, compared with all reported metal carbonate hydroxides. Benefited from 3D open nanosheet array topographic structure with tight contact between nanosheets and NF, it is able to deliver a high and stable current density of 1000 mA cm–2 at only an overpotential of 462 mV with no interference from high-flux oxygen evolution. Despite no reports about effective HER on metal carbonate hydroxides yet, the small overpotential of 180 mV at 10 mA cm–2 for HER can be also achieved on Co1Mn1CH/NF by the dual modulation of Mn doping. This offers a two-electrode electrolyzer using bifunctional Co1Mn1CH/NF as both anode and cathode to perform stable overall water splitting with a cell voltage of only 1.68 V at 10 mA cm–2. These findings may open up opportunities to explore other multimetal carbonate hydroxides as practical bifunctional electrocatalysts for scale-up water electrolysis.
Collagen is a kind of high macromolecular protein with unique tissue distribution and distinctive functions in the body. At present, most collagen products are extracted from the tissues and organs ...of mammals or marine fish. However, this method exhibits several disadvantages, including low efficiency and serious waste generation, which makes it difficult to meet the current market demand. With the rapid development of synthetic biology and the deepening of high-density fermentation technology, the collagen preparation by biosynthesis strategy emerges as the times require. Co-expression with the proline hydroxylase gene can solve the problem of non-hydroxylated collagen, but the yield may be affected. Therefore, improving the expression through molecular modification and dynamic regulation of synthesis is an entry point for future research. Due to the defects in certain properties of the natural collagen, modification of properties would be benefit for meeting the requirements of practical application. In this paper, in-depth investigations on recombinant expression, fermentation, and modification studies of collagen are conducted. Also, it summarizes the research progress of collagen in food, medicine, and beauty industry in recent years. Furthermore, the future development trend and application prospect of collagen are discussed, which would provide guidance for its preparation and application.
The performance of single‐atom electrocatalysts usually suffers from attenuation due to high energy states, especially in harsh environments. Therefore, as high‐efficiency electrocatalysts for ...hydrogen reduction reaction (HER), supported metal nanoclusters (NCs) with maximum metal atom efficiency are promising, yet the genuine mechanism involving rational orbital modulation is still arguable. Herein, the conjugating effect between electron‐donor boron (B)‐tethering engineering and iridium (Ir) that facilitates the electron capture of Ir atoms is explored, achieving highly dispersive Ir‐NCs confined in N, B co‐doped defective carbon (Ir@NBD‐C). The Ir@NBD‐C catalyst achieves displays remarkable high activity for HER in a pH‐universal range, in particular, with an ultralow overpotential of 7 mV (10 mA cm−2), high mass activity of 652.2 A gIr−1, and turnover frequency (TOF) of 1.90 H2 S−1 (100 mV) in 1.0 m KOH, outperforming almost all state‐of‐the‐art HER electrocatalysts. Operando characterizations and theoretical calculations unveil that the outstanding catalytic activity can attribute to the optimal binding to hydrogen intermediate species (H*) derived from the tunable and favorable electronic structure of the Ir site through the tethering of B heteroatoms. Undoubtedly, this work brings new insight into the design of catalysts with high intrinsic activity and thermodynamic stability.
Synergistic tethering of electron‐donor (B)/acceptor (N) heteroatoms regulates the electronic structure of Ir nanoclusters, resulting in high catalytic activity and optimal adsorption energy of hydrogen intermediate (H*) in HER.
Keratin is a kind of natural polymer that is abundant in feathers, wool, and hair. Being one of the natural biomolecules, keratin has excellent biological activity, biocompatibility, ...biodegradability, favorable material mechanical properties, and natural abundance, which exhibit significant biological and biomedical application potentials. At present, the strategies commonly used for preparing keratin from hair, feathers, wool, etc. include physical, chemical, and enzymatic methods. The present article mainly reviews the structure, classification, preparation methods, and the main biological applications of keratin, and these applications cover wound healing, hemostasis, targeted release of tissue engineering drugs, and so on. It is expected to lay the foundations for its future in-depth investigations and wide applications of keratin biomaterials.
Key points
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There are several pathways to prepare biologically active keratin from wool, feathers, and human hair, etc
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Promoting blood coagulation by keratin is related to the adhesion and activation of platelets and the aggregation of fibrin
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The biological applications of keratin, including wound healing and tissue engineering, are summarized
Pollution by heavy metals limits the area of land available for cultivation of food crops. A potential solution to this problem might lie in the molecular breeding of food crops for phytoremediation ...that accumulate toxic metals in straw while producing safe and nutritious grains. Here, we identify a rice quantitative trait locus we name cadmium (Cd) accumulation in leaf 1 (CAL1), which encodes a defensin-like protein. CAL1 is expressed preferentially in root exodermis and xylem parenchyma cells. We provide evidence that CAL1 acts by chelating Cd in the cytosol and facilitating Cd secretion to extracellular spaces, hence lowering cytosolic Cd concentration while driving long-distance Cd transport via xylem vessels. CAL1 does not appear to affect Cd accumulation in rice grains or the accumulation of other essential metals, thus providing an efficient molecular tool to breed dual-function rice varieties that produce safe grains while remediating paddy soils.
Over the past decades, nitrilases have drawn considerable attention because of their application in nitrile degradation as prominent biocatalysts. Nitrilases are derived from bacteria, filamentous ...fungi, yeasts, and plants. In-depth investigations on their natural sources function mechanisms, enzyme structure, screening pathways, and biocatalytic properties have been conducted. Moreover, the immobilization, purification, gene cloning and modifications of nitrilase have been dwelt upon. Some nitrilases are used commercially as biofactories for carboxylic acids production, waste treatment, and surface modification. This critical review summarizes the current status of nitrilase research, and discusses a number of challenges and significant attempts in its further development. Nitrilase is a significant and promising biocatalyst for catalytic applications.
Keratinases are unique among proteolytic enzymes for their ability to degrade recalcitrant insoluble proteins, and they are of critical importance in keratin waste management. Over the past few ...decades, researchers have focused on discovering keratinase producers, as well as producing and characterizing keratinases. The application potential of keratinases has been investigated in the feed, fertilizer, leathering, detergent, cosmetic, and medical industries. However, the commercial availability of keratinases is still limited due to poor productivity and properties, such as thermostability, storage stability and resistance to organic reagents. Advances in molecular biotechnology have provided powerful tools for enhancing the production and functional properties of keratinase. This critical review systematically summarizes the application potential of keratinase, and in particular certain newly discovered catalytic capabilities. Furthermore, we provide comprehensive insight into mechanistic and molecular aspects of keratinases including analysis of gene sequences and protein structures. In addition, development and current advances in protein engineering of keratinases are summarized and discussed, revealing that the engineering of protein domains such as signal peptides and pro-peptides has become an important strategy to increase production of keratinases. Finally, prospects for further development are also proposed, indicating that advanced protein engineering technologies will lead to improved and additional commercial keratinases for various industrial applications.
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