Reversal of Regioselectivity in Zinc-Dependent Medium-Chain Alcohol Dehydrogenase from Rhodococcus erythropolis toward Octanone Derivatives

Stairway to Stereoisomers: Engineering Short- and Medium-Chain Ketoreductases To Produce Chiral Alcohols

The short- and medium-chain dehydrogenase/reductase superfamilies are responsible for most chiral alcohol production in laboratories and industries. In nature, they participate in diverse roles such as detoxification, housekeeping, secondary metabolite production, and catalysis of several chemicals with commercial and environmental significance. As a result, they are used in industries to create biopolymers, active pharmaceutical intermediates (APIs), and are also used as components of modular enzymes like polyketide synthases for fabricating bioactive molecules. Consequently, random, semi-rational and rational engineering have helped transform these enzymes into product-oriented efficient catalysts. The rise of newer synthetic chemicals and their enantiopure counterparts has proved challenging, and engineering them has been the subject of numerous studies. However, they are frequently limited to the synthesis of a single chiral alcohol. The study attempts to defragment and describe hotspots of engineering short- and medium-chain dehydrogenases/reductases for the production of chiral synthons.

Rhodococcus strains as a good biotool for neutralizing pharmaceutical pollutants and obtaining therapeutically valuable products: Through the past into the future

Active pharmaceutical ingredients present a substantial risk when they reach the environment and drinking water sources. As a new type of dangerous pollutants with high chemical resistance and pronounced biological effects, they accumulate everywhere, often in significant concentrations (μg/L) in ecological environments, food chains, organs of farm animals and humans, and cause an intense response from the aquatic and soil microbiota. Rhodococcus spp. (Actinomycetia class), which occupy a dominant position in polluted ecosystems, stand out among other microorganisms with the greatest variety of degradable pollutants and participate in natural attenuation, are considered as active agents with high transforming and degrading impacts on pharmaceutical compounds. Many representatives of rhodococci are promising as unique sources of specific transforming enzymes, quorum quenching tools, natural products and novel antimicrobials, biosurfactants and nanostructures. The review presents the latest knowledge and current trends regarding the use of Rhodococcus spp. in the processes of pharmaceutical pollutants’ biodegradation, as well as in the fields of biocatalysis and biotechnology for the production of targeted pharmaceutical products. The current literature sources presented in the review can be helpful in future research programs aimed at promoting Rhodococcus spp. as potential biodegraders and biotransformers to control pharmaceutical pollution in the environment.

Reversal of Regioselectivity in Zinc-Dependent Medium-Chain Alcohol Dehydrogenase from Rhodococcus erythropolis toward Octanone Derivatives

The zinc-dependent medium-chain alcohol dehydrogenase from Rhodococcus erythropolis (ReADH) is one of the most versatile biocatalysts for the stereoselective reduction of ketones to chiral alcohols. Despite its known broad substrate scope, ReADH only accepts carbonyl substrates with either a methyl or an ethyl group adjacent to the carbonyl moiety; this limits its use in the synthesis of the chiral alcohols that serve as a building blocks for pharmaceuticals. Protein engineering to expand the substrate scope of ReADH toward bulky substitutions next to carbonyl group (ethyl 2-oxo-4-phenylbutyrate) opens up new routes in the synthesis of ethyl-2-hydroxy-4-phenylbutanoate, an important intermediate for anti-hypertension drugs like enalaprilat and lisinopril. We have performed computer-aided engineering of ReADH toward ethyl 2-oxo-4-phenylbutyrate and octanone derivatives. W296, which is located in the small binding pocket of ReADH, sterically restricts the access of ethyl 2-oxo-4-phenylbutyrate, octan-3-one or octan-4-one toward the catalytic zinc ion and thereby limits ReADH activity. Computational analysis was used to identify position W296 and site-saturation mutagenesis (SSM) yielded an improved variant W296A with a 3.6-fold improved activity toward ethyl 2-oxo-4-phenylbutyrate when compared to WT ReADH (ReADH W296A: 17.10 U/mg and ReADH WT: 4.7 U/mg). In addition, the regioselectivity of ReADH W296A is shifted toward octanone substrates. ReADH W296A has a more than 16-fold increased activity toward octan-4-one (ReADH W296A: 0.97 U/mg and ReADH WT: 0.06 U/mg) and a more than 30-fold decreased activity toward octan-2-one (ReADH W296A: 0.23 U/mg and ReADH WT: 7.69 U/mg). Computational and experimental results revealed the role of position W296 in controlling the substrate scope and regiopreference of ReADH for a variety of carbonyl substrates.