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ω‐Transaminases (ω‐TAs) show considerable potential for the synthesis of chiral amines. However, their low catalytic efficiency towards bulky substrates limits their application, and complicated catalytic mechanisms prevent precise enzyme design. Herein, we address this challenge using a mechanism‐guided computational enzyme design strategy by reprograming the transition and ground states in key reaction steps. The common features among the three high‐energy‐barrier steps responsible for the low catalytic efficiency were revealed using quantum mechanics (QM). Five key residues were simultaneously tailored to stabilize the rate‐limiting transition state with the aid of the Rosetta design. The 14 top‐ranked variants showed 16.9–143‐fold improved catalytic activity. The catalytic efficiency of the best variant, M9 (Q25F/M60W/W64F/I266A), was significantly increased, with a 1660‐fold increase in kcat/Km and a 1.5–26.8‐fold increase in turnover number (TON) towards various indanone derivatives. [ABSTRACT FROM AUTHOR]

Engineering biocatalysts with enhanced stereoselectivity is highly desirable, and active-site loop dynamics play an important role in its regulation. However, knowledge of their precise roles in catalysis and evolution is limited. Here, we used the strategy of Rosetta enzyme design combined molecular dynamic simulations (MDs) to reprogram the landscapes of the key active-site loop dynamics of the carbonyl reductase Lf SDR1 to improve stereoselectivity. The key flexible loop in the active site showed the potential to regulate the catalytic properties. A library of virtual variants was produced using the Rosetta design and assessed dynamic effect of the loop with the aid of MDs. A potential candidate was obtained with significant stereoselectivity (ee > 99 %) compared to the wild-type (ee = 42 %) without loss of catalytic activity or thermostability. The molecular basis of the catalytic property enhancement was flanked by MDs, which revealed the role of the G92L mutation in regulating loop dynamics to stabilize the environment of the active site. Finally, a series of the challenge bulky substrate derivatives were assessed using the G92L variant, and all showed improved stereoselectivity ee > 99 %. This study provides novel insights for improving stereoselectivity through rational engineering of the loop dynamics of biocatalysts. [ABSTRACT FROM AUTHOR]

Acetaldehyde dehydrogenase 2 (ALDH2) is a crucial enzyme in alcohol metabolism, and oral administration of ALDH2 is a promising method for alcohol detoxification. However, recombinant ALDH2 is susceptible to hydrolysis by digestive enzymes in the gastrointestinal tract and is expressed as inactive inclusion bodies in E. coli. In this study, we performed three rounds of rational design to address these issues. Specifically, the surface digestive sites of pepsin and trypsin were replaced with other polar amino acids, while hydrophobic amino acids were incorporated to reshape the catalytic cavity of ALDH2. The resulting mutant DE2–852 exhibited a 45-fold increase in soluble expression levels, while its stability against trypsin and pepsin increased by eightfold and twofold, respectively. Its catalytic efficiency (k cat /K m) at pH 7.2 and 3.2 improved by more than four and five times, respectively, with increased V max and decreased K m values. The enhanced properties of DE2–852 were attributed to the D457Y mutation, which created a more compact protein structure and facilitated a faster collision between the substrate and catalytic residues. These results laid the foundation for the oral administration and mass preparation of highly active ALDH2 and offered insights into the oral application of other proteins. [ABSTRACT FROM AUTHOR]

The protein universe displays a wealth of therapeutically relevant activities, but T-cell driven immune responses to non-'self' biological agents present a major impediment to harnessing the full diversity of these molecular functions. Mutagenic T-cell epitope deletion seeks to mitigate the immune response, but can typically address only a small number of epitopes. Here, we pursue a 'bottom-up' approach that redesigns an entire protein to remain native-like but contain few if any immunogenic epitopes. We do so by extending the Rosetta flexible-backbone protein design software with an epitope scoring mechanism and appropriate constraints. The method is benchmarked with a diverse panel of proteins and applied to three targets of therapeutic interest. We show that the deimmunized designs indeed have minimal predicted epitope content and are native-like in terms of various quality measures, and moreover that they display levels of native sequence recovery comparable to those of non-deimmunized designs. © 2013 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

We present the results of combining design and selection to remodel a protein–peptide binding interface, using the peptide PTIEEVD and the TPR1 module interaction as our test case. We initially used the program Rosetta to interrogate possible TPR1 sequences compatible with binding the peptide PTIEEVD. Based on these results, we screened a small library of TPR1 variants, using a split GFP fluorescent assay to identify proteins that are able to bind to the PTIEEVD peptide. We discuss the similarities and differences between the modeling and selection results at each position. We show that a new ‘consensus’ TPR1, created based on the results of the sequences identified in the screen, indeed binds to the PTIEEVD peptide. These results demonstrate the utility of combining design and selection in a synergistic fashion to remodel protein recognition interfaces. [ABSTRACT FROM PUBLISHER]

Anti-silencing function 1 (ASF1) is a conserved H3-H4 histone chaperone involved in histone dynamics during replication, transcription, and DNA repair. Overexpressed in proliferating tissues including many tumors, ASF1 has emerged as a promising therapeutic target. Here, we combine structural, computational, and biochemical approaches to design peptides that inhibit the ASF1-histone interaction. Starting from the structure of the human ASF1-histone complex, we developed a rational design strategy combining epitope tethering and optimization of interface contacts to identify a potent peptide inhibitor with a dissociation constant of 3 nM. When introduced into cultured cells, the inhibitors impair cell proliferation, perturb cell-cycle progression, and reduce cell migration and invasion in a manner commensurate with their affinity for ASF1. Finally, we find that direct injection of the most potent ASF1 peptide inhibitor in mouse allografts reduces tumor growth. Our results open new avenues to use ASF1 inhibitors as promising leads for cancer therapy. • Development of a computational pipeline for the design of high-affinity peptides • Epitope tethering and contacts optimization lead to nanomolar ASF1-binding peptides • The optimal peptide inhibited cell proliferation and perturbed cell cycle • Injected in mouse allografts, it reduced tumor growth and induced apoptosis Bakail et al. developed a strategy for designing peptide inhibitors of protein-protein interactions, based on tethering binding epitopes to increase their affinity and specificity. This strategy was applied to the inhibition of the histone chaperone ASF1, which is essential for the early steps of chromatin assembly and represents a novel target in cancer research. [ABSTRACT FROM AUTHOR]