Molecular biology interventions for activity improvement and production of industrial enzymes

Characteristics of cold-adapted carbonic anhydrase and efficient carbon dioxide capture based on cell surface display technology

Carbonic anhydrase (CA) is currently under investigation because of its potential to capture CO2. A novel N-domain of ice nucleoproteins (INPN)-mediated surface display technique was developed to produce CA with low-temperature capture CO2 based on the mining and characterization of Colwellia sp. CA (CsCA) with cold-adapted enzyme structural features and catalytic properties. CsCA and INPN were effectively integrated into the outer membrane of the cell as fusion proteins. Throughout the display process, the integrity of the membrane of engineered bacteria BL21/INPN-CsCA was maintained. Notably, the study affirmed positive applicability, wherein 94 % activity persisted after 5 d at 15 °C, and 73 % of the activity was regained after 5 cycles of CO2 capture. BL21/INPN-CsCA displayed a high CO2 capture capacity of 52 mg of CaCO3/mg of whole-cell biocatalysts during CO2 mineralization at 25 °C. Therefore, the CsCA functional cell surface display technology could contribute significantly to environmentally friendly CO2 capture.

Enzyme Engineering Strategies for the Bioenhancement of L-Asparaginase Used as a Biopharmaceutical

Over the past few years, there has been a surge in the industrial production of recombinant enzymes from microorganisms due to their catalytic characteristics being highly efficient, selective, and biocompatible. L-asparaginase (L-ASNase) is an enzyme belonging to the class of amidohydrolases that catalyzes the hydrolysis of L-asparagine into L-aspartic acid and ammonia. It has been widely investigated as a biologic agent for its antineoplastic properties in treating acute lymphoblastic leukemia. The demand for L-ASNase is mainly met by the production of recombinant type II L-ASNase from Escherichia coli and Erwinia chrysanthemi. However, the presence of immunogenic proteins in L-ASNase sourced from prokaryotes has been known to result in adverse reactions in patients undergoing treatment. As a result, efforts are being made to explore strategies that can help mitigate the immunogenicity of the drug. This review gives an overview of recent biotechnological breakthroughs in enzyme engineering techniques and technologies used to improve anti-leukemic L-ASNase, taking into account the pharmacological importance of L-ASNase.

Easy and Versatile Technique for the Preparation of Stable and Active Lipase-Based CLEA-like Copolymers by Using Two Homofunctional Cross-Linking Agents: Application to the Preparation of Enantiopure Ibuprofen

An easy and versatile method was designed and applied successfully to obtain access to lipase-based cross-linked-enzyme aggregate-like copolymers (CLEA-LCs) using one-pot, consecutive cross-linking steps using two types of homobifunctional cross-linkers (glutaraldehyde and putrescine), mediated with amine activation through pH alteration (pH jump) as a key step in the process. Six lipases were utilised in order to assess the effectiveness of the technique, in terms of immobilization yields, hydrolytic activities, thermal stability and application in kinetic resolution. A good retention of catalytic properties was found for all cases, together with an important thermal and storage stability improvement. Particularly, the CLEA-LCs derived from Candida rugosa lipase showed an outstanding behaviour in terms of thermostability and capability for catalysing the enantioselective hydrolysis of racemic ibuprofen ethyl ester, furnishing the eutomer (S)-ibuprofen with very high conversion and enantioselectivity.

Improving the Thermostability of Serine Protease PB92 from Bacillus alcalophilus via Site-Directed Mutagenesis Based on Semi-Rational Design

Proteases have been widely employed in many industrial processes. In this work, we aimed to improve the thermostability of the serine protease PB92 from Bacillus alcalophilus to meet the high-temperature requirements of biotechnological treatments. Eight mutation sites (N18, S97-S101, E110, and R143) were identified, and 21 mutants were constructed from B-factor comparison and multiple sequence alignment and expressed via Bacillus subtilis. Among them, fifteen mutants exhibited increased half-life (t1/2) values at 65 °C (1.13-31.61 times greater than that of the wild type). Based on the composite score of enzyme activity and thermostability, six complex mutants were implemented. The t1/2 values of these six complex mutants were 2.12-10.05 times greater than that of the wild type at 65 °C. In addition, structural analysis revealed that the increased thermal stability of complex mutants may be related to the formation of additional hydrophobic interactions due to increased hydrophobicity and the decreased flexibility of the structure. In brief, the thermal stability of the complex mutants N18L/R143L/S97A, N18L/R143L/S99L, and N18L/R143L/G100A was increased 4-fold, which reveals application potential in industry.

Transglutaminase in Foods and Biotechnology

Stabilization and reusability of enzyme transglutaminase (TGM) are important goals for the enzymatic process since immobilizing TGM plays an important role in different technologies and industries. TGM can be used in many applications. In the food industry, it plays a role as a protein-modifying enzyme, while, in biotechnology and pharmaceutical applications, it is used in mediated bioconjugation due to its extraordinary crosslinking ability. TGMs (EC 2.3.2.13) are enzymes that catalyze the formation of a covalent bond between a free amino group of protein-bound or peptide-bound lysine, which acts as an acyl acceptor, and the γ-carboxamide group of protein-bound or peptide-bound glutamine, which acts as an acyl donor. This results in the modification of proteins through either intramolecular or intermolecular crosslinking, which improves the use of the respective proteins significantly.

Current state of molecular and metabolic strategies for the improvement of L-asparaginase expression in heterologous systems

Heterologous expression of L-asparaginase (L-ASNase) has become an important area of research due to its clinical and food industry applications. This review provides a comprehensive overview of the molecular and metabolic strategies that can be used to optimize the expression of L-ASNase in heterologous systems. This article describes various approaches that have been employed to increase enzyme production, including the use of molecular tools, strain engineering, and in silico optimization. The review article highlights the critical role that rational design plays in achieving successful heterologous expression and underscores the challenges of large-scale production of L-ASNase, such as inadequate protein folding and the metabolic burden on host cells. Improved gene expression is shown to be achievable through the optimization of codon usage, synthetic promoters, transcription and translation regulation, and host strain improvement, among others. Additionally, this review provides a deep understanding of the enzymatic properties of L-ASNase and how this knowledge has been employed to enhance its properties and production. Finally, future trends in L-ASNase production, including the integration of CRISPR and machine learning tools are discussed. This work serves as a valuable resource for researchers looking to design effective heterologous expression systems for L-ASNase production as well as for enzymes production in general.

Highly efficient low-temperature biodegradation of polyethylene microplastics by using cold-active laccase cell-surface display system

To eliminate efficiency restriction of polyethylene microplastics low-temperature biodegradation, a novel InaKN-mediated Escherichia coli surface display platform for cold-active degrading laccase PsLAC production was developed. Display efficiency of 88.0% for engineering bacteria BL21/pET-InaKN-PsLAC was verified via subcellular extraction and protease accessibility, exhibiting an activity load of 29.6 U/mg. Cell growth and membrane integrity revealed BL21/pET-InaKN-PsLAC maintained stable growth and intact membrane structure during the display process. The favorable applicability was confirmed, with 50.0% activity remaining in 4 days at 15 °C, and 39.0% activity recovery retention after 15 batches of activity substrate oxidation reactions. Moreover, BL21/pET-InaKN-PsLAC possessed high polyethylene low-temperature depolymerizing capacity. Bioremediation experiments proved that the degradation rate was 48.0% within 48 h at 15 °C, and reached 66.0% after 144 h. Collectively, cold-active PsLAC functional surface display technology and its significant contributions to polyethylene microplastics low-temperature degradation constitute an effective improvement strategy for biomanufacturing and microplastics cold remediation.

[Approaches for improving L-asparaginase expression in heterologous systems]

L-asparaginase (EC 3.5.1.1) is one of the most demanded enzymes used in the pharmaceutical industry as a drug and in the food industry to prevent the formation of toxic acrylamide. Researchers aimed to improve specific activity and reduce side effects to create safer and more potent enzyme products. However, protein modifications and heterologous expression remain problematic in the production of asparaginases from different species. Heterologous expression in optimized producer strains is rationally organized; therefore, modified and heterologous protein expression is enhanced, which is the main strategy in the production of asparaginase. This strategy solves several problems: incorrect protein folding, metabolic load on the producer strain and codon misreading, which affects translation and final protein domains, leading to a decrease in catalytic activity. The main approaches developed to improve the heterologous expression of L-asparaginases are considered in this paper.

Engineering multifunctional enzymes for agro-biomass utilization

Lignocellulosic biomass is a plentiful renewable resource that can be converted into a wide range of high-value-added industrial products. However, the complexity of its structural integrity is one of the major constraints and requires combinations of different fibrolytic enzymes for the cost-effective, industrially and environmentally feasible transformation. An interesting approach is constructing multifunctional enzymes, either in a single polypeptide or by joining multiple domains with linkers and performing diverse reactions simultaneously, in a single host. The production of such chimera proteins multiplies the advantages of different enzymatic reactions in a single setup, in lesser time, at lower production cost and with desirable and improved catalytic activities. This review embodies the various domain-tailoring and extracellular secretion strategies, possible solutions to their challenges, and efforts to experimentally connect different catalytic activities in a single host, as well as their applications.

Uses of knockout, knockdown, and transgenic models in the studies of glucose transporter 4

Currently, glucose transporter 4 (GLUT4) has been considered as the key player for the insulin-stimulated glucose transport in the muscle and adipose tissues. The development of recombinant DNA techniques allows the creations of genetically knockout, knockdown and transgenic animals and cells for the study of GLUT4’s physiological functions. Here, we have used key words to search the PubMed and summarized the methods used in Slc2a4 gene knockout, GLUT4 knockdown and overexpression in the whole body and tissue specific manner. The whole body GLUT4-null mice have growth retardation, but normal glucose tolerance and basal glucose turnover rates. Compared with whole body Slc2a4 knockout mice, adipose and muscle double knockout mice have impaired insulin tolerance and glucose intolerance. The results of GLUT4 knockdown in 3T3-L1 adipocytes have shown that its expression is needed for lipogenesis after, but not during, differentiation. Transgenic mice with the whole body GLUT4 overexpression have normal body weight and lowered blood glucose level. The adipose tissue specific overexpression of GLUT4 leads to increases in mouse body weight and adipose tissue weight. The insulin-stimulated GLUT4 translocation in the skeletal muscle contributes to the regulation of glucose homeostasis. Data from both transgenic overexpression and tissue specific Slc2a4 knockout indicate that GLUT4 probably plays a role in the glucose uptake in the fasting state. More studies are warranted to use advanced molecular biology tools to decipher the roles of GLUT4 in the control of glucose homeostasis.

Virus-templated magnetic composite hydrogels for surface immobilization of mimic-free-lipase

Surface immobilization of enzymes on magnetic-recoverable carriers is of great interest and importance for the biocatalysis of relatively large molecules. In this work, the nanosized amino-rich filamentous M13 virus, a versatile biological scaffold, was applied as the unique soft backbone for lipase immobilization. Based on the structure and capsid proteins of M13 phages, the magnetic-recoverable mimic-free-lipases (MFLs) composed of the M13 hydrogels and magnetic particles were developed in two designs. In the first design, nanosized wild M13 phages were crosslinked into a phage hydrogel through the N-terminals of pVIII peptides while NH₂-Fe₃O₄ magnetic nanoparticles (MNPs) were attached to the M13 virus through glutaraldehyde, forming the M13-(NH₂-Fe₃O₄) magnetic phage hydrogel. In the second design, special M13 with Fe₃O₄ affinity pIII-peptide (FAP-M13) was biopanned for strongly binding towards bare Fe₃O₄ with the "hook"-like pIII-peptide (N-LPLSTQH-C). TEM observation confirmed the direct grasp of FAP-M13 on bare Fe₃O₄, forming the magnetic (FAP-M13)-Fe₃O₄ virus hydrogel. Lipases were uniformly anchored on the phage surface of nanoscale by crosslinking with the N-terminals of pVIII peptides, and then lipase@M13-(NH₂-Fe₃O₄) and lipase@(FAP-M13)-Fe₃O₄ MFLs were constructed. For both MFLs, high activity recovery yield (>95%) and efficient magnetic separation were characterized. Significantly reduced MNP-usage-amount and enhanced lipase-loading-amount both by about 40 folds were obtained, compared with the conventional NH₂-Fe₃O₄ carriers. The quantified K_m and V_max/K_m values were almost equal to those of the free lipases, verifying free-enzyme-mimicking features of the MFLs. High pH-tolerance, wide temperature adaptability, enhanced thermal stability and stable magnetic separation capability of both MFLs were also observed. In particular, the (FAP-M13)-Fe₃O₄ magnetic virus hydrogel simply using bare Fe₃O₄ MNPs would be more convenient and economical in the scaled-up biocatalysis.

Purification, characterization, and antifungal activity of Bacillus cereus strain NK91 chitinase from rhizospheric soil samples of Himachal Pradesh, India

Newly isolated Bacillus cereus strain NK91 was characterized for extracellular chitinase production. Partially purified chitinase showed a molecular weight of 43.7 kDa in SDS-PAGE analysis. The optimum pH and temperature for the partially purified enzyme were 7.0 and 40°C, respectively. The addition of Mn²⁺ resulted in a 21% increase in enzyme activity as compared to the control. The V_max and K_m of the enzyme were determined as 76.9 μmol/min and 0.07 mg/mL, respectively. This enzyme exhibited stronger antifungal activity towards Fusarium oxysporum (66.7%), Rhizoctonia solani (64.6%), and Colletotrichum gloeosporioides (63%), and transmission electron microscopy and scanning transmission electron microscopy analysis showed considerable changes in cell wall structure with the treatment of purified chitinase as compared to control. Therefore, this enzyme reveals its biocontrol potential against potent phytopathogens in agriculture that can be helpful in swapping harmful as well as expensive fungicides.

Cost-effective production of biocatalysts using inexpensive plant biomass: a review

Enzymes are the complex protein moieties, catalyze the rate of chemical reactions by transforming various substrates to specific products and play an integral part in multiple biochemical cycles. Advancement in enzyme research and its integration with industries have reformed the biotech industries. It provides a superior monetary and ecological exchange to traditional material measures in an efficient and environmentally sustainable manner. The cost-effective production of pure and highly active enzymes is still a challenge for the biocatalyst industries. The use of high purity substrates further raises the cost of a typical biocatalyst. The use of low-cost plant-based biomasses as an enticing and sustainable substrate for enzyme production is the most cost-effective approach to these problems. Given the relevance of biomass as a substrate for enzyme development, this review article focuses on the key source, composition and major enzyme generated using various biomass residues. Furthermore, the difficulties associated with the use of biomass as a substrate and technical developments in this area, are also addressed. The use of waste biomass as a substrate lowers the ultimate cost for the production of biocatalysts while simultaneously reduces the waste burden from the environment.