Structural-Based Modeling in Protein Engineering. A Must Do

Chimeric enzymes in the pulp and paper making industry: Current developments

The pulp and paper (P&P) industry plays a vital role in supporting the social and economic progress of a country by supplying essential commodities. Conventional P&P processing often consumes significant energy and use chemical agents to produce hazardous intermediates. The use of enzymes in the P&P industry has significantly reduced both the chemical and energy demands during processing. A variety of enzyme combination cocktails are used to perform multiple functions in a single step, but often fail to operate synergistically because of significant differences in operational conditions. This lack of synergy under various operating conditions highlights the need for engineered chimeric enzymes. Moreover, enzyme engineering approaches enable enzymes to perform catalysis in sub-optimal environment. Enzymes have been engineered to improve their catalytic properties and enhance operational stability. Designing multifunctional or chimeric enzymes can function simultaneously across diverse operational conditions. Chimeric enzymes enable effective synergistic action of multiple enzymes in the P&P industry. This review aims to provide clear insights into the selective development of chimeric enzymes using enzyme engineering approaches for their effective use in the P&P industry.

Boosting the catalytic efficiency of UGT51 for efficient production of rare ginsenoside Rh2

Ginsenoside Rh2(S) is well-known for its therapeutic potential against diverse conditions, including some cancers, inflammation, and diabetes. The enzymatic activity of uridine diphosphate glycosyltransferase 51 (UGT51) from Saccharomyces cerevisiae plays a pivotal role in the glycosylation process between UDP-glucose (donor) and protopanaxadiol (acceptor), to form ginsenoside Rh2. However, the catalytic efficiency of the UGT51 has remained a challenging task. To this end, we employed site-directed mutagenesis on UGT51 to improve its catalytic efficiency for enhanced production of ginsenoside Rh2. The mutated structure, featuring four key mutations (E805A, S998A, R1031A, and L1032A), exhibited heightened stability, binding affinity, and active site accessibility for protopanaxadiol (PPD) compared to the wild type. Under in vitro conditions, three mutants (E805A, R1031A, and L1032A) demonstrated 10%, 58%, and 65% higher enzymatic activities compared to the wild strain. Notably, the double mutant R1031A/L1032A exhibited an 85% increase in activity. Employing a fed-batch technology with PPD as the substrate yielded a Rh2 production of 4.663 g/L. The molecular dynamics (MD) simulations were employed to investigate the movements and dynamic dynamics of UGT51 mutations and PPD complexes. The root mean square deviation (RMSD) analysis revealed substantial alterations in structural conformation, particularly in the R1031A/L1032A mutations, correlating with boosted catalytic efficiency. Furthermore, the root mean square fluctuation (RMSF) simulation study aligned with both the RMSD and the solvent-accessible surface area (SASA) analyses. The computationally guided site-directed mutagenesis approach holds promise for extending its application to the development of commercially significant enzymes.

AsiteDesign: a Semirational Algorithm for an Automated Enzyme Design

With advances in protein structure predictions, the number of available high-quality structures has increased dramatically. In light of these advances, structure-based enzyme engineering is expected to become increasingly important for optimizing biocatalysts for industrial processes. Here, we present AsiteDesign, a Monte Carlo-based protocol for structure-based engineering of active sites. AsiteDesign provides a framework for introducing new catalytic residues in a given binding pocket to either create a new catalytic activity or alter the existing one. AsiteDesign is implemented using pyRosetta and incorporates enhanced sampling techniques to efficiently explore the search space. The protocol was tested by designing an alternative catalytic triad in the active site of Pseudomonas fluorescens esterase (PFE). The designed variant was experimentally verified to be active, demonstrating that AsiteDesign can find alternative catalytic triads. Additionally, the AsiteDesign protocol was employed to enhance the hydrolysis of a bulky chiral substrate (1-phenyl-2-pentyl acetate) by PFE. The experimental verification of the designed variants demonstrated that F158L/F198A and F125A/F158L mutations increased the hydrolysis of 1-phenyl-2-pentyl acetate from 8.9 to 66.7 and 23.4%, respectively, and reversed the enantioselectivity of the enzyme from (R) to (S)-enantiopreference, with 32 and 55% enantiomeric excess (ee), respectively.

The Sabatier principle as a tool for discovery and engineering of industrial enzymes

The recent breakthrough in all-atom, protein structure prediction opens new avenues for a range of computational approaches in enzyme design. These new approaches could become instrumental for the development of technical biocatalysts, and hence our transition toward more sustainable industries. Here, we discuss one approach, which is well-known within inorganic catalysis, but essentially unexploited in biotechnology. Specifically, we review examples of linear free-energy relationships (LFERs) for enzyme reactions and discuss how LFERs and the associated Sabatier Principle may be implemented in algorithms that estimate kinetic parameters and enzyme performance based on model structures.

Design and Characterization of In-One Protease-Esterase PluriZyme

Proteases are abundant in prokaryotic genomes (~10 per genome), but their recovery encounters expression problems, as only 1% can be produced at high levels; this value differs from that of similarly abundant esterases (1-15 per genome), 50% of which can be expressed at good levels. Here, we design a catalytically efficient artificial protease that can be easily produced. The PluriZyme EH1AB1 with two active sites supporting the esterase activity was employed. A Leu24Cys mutation in EH1AB1, remodelled one of the esterase sites into a proteolytic one through the incorporation of a catalytic dyad (Cys24 and His214). The resulting artificial enzyme, EH1AB1C, efficiently hydrolysed (azo)casein at pH 6.5-8.0 and 60-70 °C. The presence of both esterase and protease activities in the same scaffold allowed the one-pot cascade synthesis (55.0 ± 0.6% conversion, 24 h) of L-histidine methyl ester from the dipeptide L-carnosine in the presence of methanol. This study demonstrates that active sites supporting proteolytic activity can be artificially introduced into an esterase scaffold to design easy-to-produce in-one protease-esterase PluriZymes for cascade reactions, namely, the synthesis of amino acid esters from dipeptides. It is also possible to design artificial proteases with good production yields, in contrast to natural proteases that are difficult to express.

A Plurizyme with Transaminase and Hydrolase Activity Catalyzes Cascade Reactions

Engineering dual‐function single polypeptide catalysts with two abiotic or biotic catalytic entities (or combinations of both) supporting cascade reactions is becoming an important area of enzyme engineering and catalysis. Herein we present the development of a PluriZyme, TR₂E₂, with efficient native transaminase (k_cat: 69.49±1.77 min⁻¹) and artificial esterase (k_cat: 3908–0.41 min⁻¹) activities integrated into a single scaffold, and evaluate its utility in a cascade reaction. TR₂E₂ (pH_opt: 8.0–9.5; T_opt: 60–65 °C) efficiently converts methyl 3‐oxo‐4‐(2,4,5‐trifluorophenyl)butanoate into 3‐(R)‐amino‐4‐(2,4,5‐trifluorophenyl)butanoic acid, a crucial intermediate for the synthesis of antidiabetic drugs. The reaction proceeds through the conversion of the β‐keto ester into the β‐keto acid at the hydrolytic site and subsequently into the β‐amino acid (e.e. >99 %) at the transaminase site. The catalytic power of the TR₂E₂PluriZyme was proven with a set of β‐keto esters, demonstrating the potential of such designs to address bioinspired cascade reactions.