Publication in ChemBioChem

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Babkova P, Sebestova E, Brezovsky J, Chaloupkova R, Damborsky J, 2017: Ancestral Haloalkane Dehalogenases Show Robustness and Unique Substrate Specificity. ChemBioChem (in press, doi:10.1002/cbic.201700197). full text.

Ancestral sequence reconstruction (ASR) represents a powerful approach for empirical testing structure-function relationships of diverse proteins. We employed ASR to predict sequences of five ancestral haloalkane dehalogenases (HLDs) from the HLD-II subfamily. Genes encoding the inferred ancestral sequences were synthesized and expressed in Escherichia coli and the resurrected ancestral enzymes AncHLD1-5 were experimentally characterized. Strikingly, the ancestral HLDs exhibited significantly enhanced thermodynamic stability compared to extant enzymes (ΔTm up to 24 °C). Compared to extant HLDs, the ancestors displayed higher specific activities with preference for short multi-substituted halogenated substrates. Moreover, multivariate statistical analysis revealed a shift in the substrate specificity profiles of AncHLD1 and AncHLD2, which would be extremely difficult to achieve by rational protein engineering. The study highlights that ASR is an efficient approach for development of novel biocatalysts and robust templates for directed evolution.

Publication in Angewandte Chemie International Edition

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Liskova V, Stepankova V, Bednar D, Brezovsky J, Prokop Z, Chaloupkova R, Damborsky J, 2017: Different Structural Origins of the Enantioselectivity of Haloalkane Dehalogenases toward Linear β-Haloalkanes: Open–Solvated versus Occluded–Desolvated Active Sites. Angewandte Chemie International Edition (in press, doi:10.1002/anie.201611193). full text

Two recipes for success: Two distinct mechanisms are described for the enantiodiscrimination of 2-bromopentane by haloalkane dehalogenases. Highly enantioselective DbjA has a very open, solvent-accessible active site. The engineered enzyme DhaA31 has a more occluded and less solvated cavity (see picture) but shows similar enantioselectivity as a result of steric hindrance imposed by two specific residues, rather than hydration as in DbjA.

Publication in Journal of Molecular Catalysis B: Enzymatic

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Grulich M, Brezovsky J, Stepanek V, Palyzova A, Maresova H, Zahradnik J, Kyslikova E, Kyslik P, 2016: In-silico driven engineering of enantioselectivity of a penicillin G acylase towards active pharmaceutical ingredients. Journal of Molecular Catalysis B: Enzymatic (in press, doi:10.1016/j.molcatb.2016.11.014). full text

Penicillin G acylase is one of the most employed enzymes in the pharmaceutical industry due to its role in the biotransformation of semi-synthetic β-lactam antibiotics. Recently, the enantioselectivity of the penicillin G acylase markedly broadened its application potential. In this study, we have evaluated effects of in-silico replacements of acyl-binding subsite residue Phe24β of the enzyme from Achromobacter sp. CCM 4824 to seven markedly smaller amino acids on its enantioselectivity towards industrially relevant compounds. Models of the two most promising mutants bearing substitutions Pheβ24Ala and Pheβ24Cys were investigated using molecular docking calculations. The Cys substitution revealed much better enantioselectivity traits with a set of seven substrates. To verify the relevance of in-silico predictions, we constructed a PGAA + Phe24βCys mutant and determined its enantioselectivity in biocatalytic reactions. Since we experimentally confirmed all these predictions, we expanded our in-silico analysis to another set of seven compounds: the prediction suggested increased enantioselectivity for N-phenylacetyl-p-F-α-phenylalanine.The (R)-enantiomer of this substrate is used as a building block in synthesis of important anti-cancer agent Abarelix. The enantioselectivity of PGAA + Phe24βCys mutant towards this substrate was improved by 75% reaching E-value of about 70. Our results suggest the rapid identification of interesting replacements altering enantioselectivity using in-silico approach as the way for further expanding biotechnological application of penicillin G acylase.