Enhancing the Catalytic Performance of a CYP116B Monooxygenase by Transdomain Combination Mutagenesis

Whole-Cell P450 Biocatalysis Using Engineered Escherichia coli with Fine-Tuned Heme Biosynthesis

By exploiting versatile P450 enzymes, whole-cell biocatalysis can be performed to synthesize valuable compounds in Escherichia coli. However, the insufficient supply of heme limits the whole-cell P450 biocatalytic activity. Here a strategy for improving intracellular heme biosynthesis to enhance the catalytic efficiencies of P450s is reported. After comparing the effects of improving heme transport and biosynthesis on P450 activities, intracellular heme biosynthesis is optimized through the integrated expression of necessary synthetic genes at proper ratios and the assembly of rate-limiting enzymes using DNA-guided scaffolds. The intracellular heme level is fine-tuned by the combined use of mutated heme-sensitive biosensors and small regulatory RNA systems. The catalytic efficiencies of three different P450s, BM3, sca-2, and CYP105D7, are enhanced through fine-tuning heme biosynthesis for the synthesis of hydroquinone, pravastatin, and 7,3',4'-trihydroxyisoflavone as example products of chemical intermediate, drug, and natural product, respectively. This strategy of fine-tuned heme biosynthesis will be generally useful for developing whole-cell biocatalysts involving hemoproteins.

Self-Sufficient Class VII Cytochromes P450: From Full-Length Structure to Synthetic Biology Applications

Members of class VII cytochromes P450 are catalytically self-sufficient enzymes containing a phthalate dioxygenase reductase-like domain fused to the P450 catalytic domain. Among these, CYP116B46 is the first enzyme for which the 3D structure of the whole polypeptide chain has been solved, shedding light on the interaction between its domains, which is crucial for catalysis. Most of these enzymes have been isolated from extremophiles or detoxifying bacteria that can carry out regio- and enantioselective oxidation of compounds of biotechnological interest. Protein engineering has generated mutants that can perform challenging organic reactions such as the anti-Markovnikov alkene oxidation. This potential, combined with the detailed 3D structure, forms the basis for further directed evolution studies aimed at widening their biotechnological exploitation.

Exploring Catalysis Specificity of Phytoene Dehydrogenase CrtI in Carotenoid Synthesis

Carotenoids, a variety of natural products, have significant pharmaceutical and commercial potential. Phytoene dehydrogenase (CrtI) is the rate-limit enzyme for carotenoid synthesis, whose catalysis specificity results in various carotenoids. However, the structural characteristics of CrtI for controlling the catalysis specificity on dehydrogenation steps are still unclear, which limited the development of CrtI function. Here we confirmed two mutation sites H136 and H453 in the mutant library of CrtI from Blakeslea trispora, which markedly regulated catalytic specificity. Interestingly, the sequence alignment features at H136 and H453 were consistent with the phylogenetic analysis of CrtI families. Subsequently, the functions of saturated mutants at H136 and H453 were clustered by principal component analysis (PCA) and k-means. According to the clustering results, diversiform mutants with specific dehydrogenation function provided important application value for carotenoid product customization. Meanwhile, this study also enriched the theory of enzyme evolution and guided the functional development of enzymes.

Biotechnological Methods of Sulfoxidation: Yesterday, Today, Tomorrow

The production of chiral sulphoxides is an important part of the chemical industry since they have been used not only as pharmaceuticals and pesticides, but also as catalysts or functional materials. The main purpose of this review is to present biotechnological methods for the oxidation of sulfides. The work consists of two parts. In the first part, examples of biosyntransformation of prochiral sulfides using whole cells of bacteria and fungi are discussed. They have more historical significance due to the low predictability of positive results in relation to the workload. In the second part, the main enzymes responsible for sulfoxidation have been characterized such as chloroperoxidase, dioxygenases, cytochrome flavin-dependent monooxygenases, and P450 monooxygenases. Particular emphasis has been placed on the huge variety of cytochrome P450 monooxygenases, and flavin-dependent monooxygenases, which allows for pure sulfoxides enantiomers effectively to be obtained. In the summary, further directions of research on the optimization of enzymatic sulfoxidation are indicated.

Engineering P450LaMO stereospecificity and product selectivity for selective C–H oxidation of tetralin-like alkylbenzenes

Via Phe scanning based protein engineering, P450_LaMO increased enantioselectivity to er 98 : 2 and product selectivity, alcohol : ketone, to ak 99 : 1.