@article {8462, title = {A curated list of targeted optimized promiscuous ketoreductases (TOP-K). [Bugworks Research Pvt. Ltd., a C-CAMP Startup]}, journal = {Biochem J}, volume = {480}, year = {2023}, month = {2023 Jul 12}, pages = {975-997}, abstract = {

Enzymes are either specific or promiscuous catalysts in nature. The latter is portrayed by protein families like CYP450Es, Aldo-ketoreductases and short/medium-chain dehydrogenases which participate in detoxification or secondary metabolite production. However, enzymes are evolutionarily {\textquoteright}blind{\textquoteright} to an ever-increasing synthetic substrate library. Industries and laboratories have circumvented this by high-throughput screening or site-specific engineering to synthesize the product of interest. However, this paradigm entails cost and time-intensive one-enzyme, one-substrate catalysis model. One of the superfamilies regularly used for chiral alcohol synthesis are short-chain dehydrogenases/reductases (SDRs). Our objective is to determine a superset of promiscuous SDRs that can catalyze multiple ketones. They are typically classified into shorter {\textquoteright}Classical{\textquoteright} and longer {\textquoteright}Extended{\textquoteright} type ketoreductases. However, current analysis of modelled SDRs reveals a length-independent conserved N-terminus Rossmann-fold and a variable substrate-binding C-terminus substrate-binding region for both categories. The latter is recognized to influence the enzyme{\textquoteright}s flexibility and substrate promiscuity and we hypothesize these properties are directly linked with each other. We tested this by catalyzing ketone intermediates with the essential and specific enzyme: FabG_E, as well as non-essential SDRs such as UcpA and IdnO. The experimental results confirmed this biochemical-biophysical association, making it an interesting filter for ascertaining promiscuous enzymes. Hence, we created a dataset of physicochemical properties derived from the protein sequences and employed machine learning algorithms to examine potential candidates. This resulted in 24 targeted optimized ketoreductases (TOP-K) from 81 014 members. The experimental validation of select TOP-Ks demonstrated the correlation between the C-terminal lid-loop structure, enzyme flexibility and turnover rate on pro-pharmaceutical substrates.

}, keywords = {ketoreductases, machine learning, medium-chain dehydrogenases, short-chain dehydrogenases}, issn = {1470-8728}, doi = {10.1042/BCJ20230051}, url = {https://pubmed.ncbi.nlm.nih.gov/37335080/}, author = {Shanbhag, Anirudh P and Rajagopal, Sreenath and Ghatak, Arindam and Katagihallimath, Nainesh and Subramanian, Ramaswamy and Datta, Santanu} } @article {1861, title = {Structure and function relationship of OqxB efflux pump from Klebsiella pneumoniae [Bugworks, a C-CAMP startup]}, journal = {Nature communications}, volume = {12}, year = {2021}, month = {09/2021}, pages = {1{\textendash}12}, type = {Journal Article}, abstract = {

OqxB is an RND (Resistance-Nodulation-Division) efflux pump that has emerged as a factor contributing to the antibiotic resistance in Klebsiella pneumoniae. OqxB underwent horizontal gene transfer and is now seen in other Gram-negative bacterial pathogens including Escherichia coli, Enterobacter cloacae and Salmonella spp., further disseminating multi-drug resistance. In this study, we describe crystal structure of OqxB with n-dodecyl-β-D-maltoside (DDM) molecules bound in its substrate-binding pocket, at 1.85 {\r A} resolution. We utilize this structure in computational studies to predict the key amino acids contributing to the efflux of fluoroquinolones by OqxB, distinct from analogous residues in related transporters AcrB and MexB. Finally, our complementation assays with mutated OqxB and minimum inhibitory concentration (MIC) experiments with clinical isolates of E. coli provide further evidence that the predicted structural features are indeed involved in ciprofloxacin efflux.

}, doi = {https://doi.org/10.1038/s41467-021-25679-0}, url = {https://www.nature.com/articles/s41467-021-25679-0}, author = {Bharatham, Nagakumar and Bhowmik, Purnendu and Aoki, Maho and Okada, Ui and Sharma, Sreevalli and Yamashita, Eiki and Shanbhag, Anirudh P and Rajagopal, Sreenath and Thomas, Teby and Sarma, Maitrayee and others} } @article {764, title = {Nitrothiophene carboxamides, a novel narrow spectrum antibacterial series: Mechanism of action and Efficacy [Bugworks Res. Pvt. Ltd., a C-CAMP Startup]}, journal = {Sci Rep}, volume = {8}, year = {2018}, month = {2018 May 08}, pages = {7263}, abstract = {

The mechanism of efflux is a tour-de-force in the bacterial armoury that has thwarted the development of novel antibiotics. We report the discovery of a novel chemical series with potent antibacterial properties that was engineered to overcome efflux liability. Compounds liable to efflux specifically via the Resistance Nodulation and cell Division (RND) pump, AcrAB-TolC were chosen for a hit to lead progression. Using structure-based design, the compounds were optimised to lose their binding to the efflux pump, thereby making them potent on wild-type bacteria. We discovered these compounds to be pro-drugs that require activation in E. coli by specific bacterial nitroreductases NfsA and NfsB. Hit to lead chemistry led to the generation of compounds that were potent on wild-type and multi-drug resistant clinical isolates of E. coli, Shigella spp., and Salmonella spp. These compounds are bactericidal and efficacious in a mouse thigh infection model.

}, issn = {2045-2322}, doi = {10.1038/s41598-018-25407-7}, author = {Hameed P, Shahul and Bharatham, Nagakumar and Katagihallimath, Nainesh and Sharma, Sreevalli and Nandishaiah, Radha and Shanbhag, Anirudh P and Thomas, Teby and Narjari, Riya and Sarma, Maitrayee and Bhowmik, Purnendu and Amar, Prakruthi and Ravishankar, Rajani and Jayaraman, Ramesh and Muthan, Kubendran and Subbiah, Ramesh and Ramachandran, Vasanthi and Balasubramanian, V and Datta, Santanu} } @article {889, title = {A strategy to identify a ketoreductase that preferentially synthesizes pharmaceutically relevant (S)-alcohols using whole-cell biotransformation [Bugworks Res. Pvt. Ltd., a C-CAMP Startup]}, journal = {Microb Cell Fact}, volume = {17}, year = {2018}, month = {2018 Dec 03}, pages = {192}, abstract = {

INTRODUCTION: Chemical industries are constantly in search of an expeditious and environmentally benign method for producing chiral synthons. Ketoreductases have been used as catalysts for enantioselective conversion of desired prochiral ketones to their corresponding alcohol. We chose reported promiscuous ketoreductases belonging to different protein families and expressed them in E.\ coli to evaluate their ability as whole-cell catalysts for obtaining chiral alcohol intermediates of pharmaceutical importance. Apart from establishing a method to produce high value (S)-specific alcohols that have not been evaluated before, we propose an in silico analysis procedure\ to predict product chirality.

RESULTS: Six enzymes originating from Sulfolobus\ sulfotaricus, Zygosaccharomyces\ rouxii, Hansenula\ polymorpha, Corynebacterium sp. ST-10, Synechococcus sp. PCC\ 7942 and Bacillus sp. ECU0013 with reported efficient activity for dissimilar substrates are compared here to arrive at an optimal enzyme for the method. Whole-cell catalysis of ketone intermediates for drugs like Aprepitant, Sitagliptin and Dolastatin using E.\ coli over-expressing these enzymes yielded (S)-specific chiral alcohols. We explain this chiral specificity for the best-performing enzyme, i.e., Z.\ rouxii ketoreductase using in silico modelling and MD simulations. This rationale was applied to five additional ketones that are used in the synthesis of Crizotinib, MA-20565\ (an antifungal agent), Sulopenem, Rivastigmine, Talampanel and Barnidipine and predicted the yield of (S) enantiomers. Experimental evaluation matched the in silico analysis wherein ~ 95\% (S)-specific alcohol with a chemical yield of 23-79\% was obtained through biotransformation. Further, the cofactor re-cycling was optimized by switching the carbon source from glucose to sorbitol that improved the chemical yield to 85-99\%.

CONCLUSIONS: Here, we present a strategy to synthesize pharmaceutically relevant chiral alcohols by ketoreductases using a cofactor balanced whole-cell catalysis scheme that is useful for the industry. Based on the results obtained in these trials, Zygosaccharomyces\ rouxii ketoreductase was identified as a proficient enzyme to obtain (S)-specific alcohols from their respective ketones. The whole-cell catalyst when combined with nutrient modulation of using sorbitol as a carbon source helped obtain high enantiomeric and chemical yield.

}, issn = {1475-2859}, doi = {10.1186/s12934-018-1036-2}, author = {Haq, Saiful F and Shanbhag, Anirudh P and Karthikeyan, Subbulakshmi and Hassan, Imran and Thanukrishnan, Kannan and Ashok, Abhishek and Sukumaran, Sunilkumar and Ramaswamy, S and Bharatham, Nagakumar and Datta, Santanu and Samant, Shalaka and Katagihallimath, Nainesh} } @article {524, title = {Delineating Substrate Diversity of Disparate Short-Chain Dehydrogenase Reductase from Debaryomyces hansenii [Bugworks Res. Pvt. Ltd., a C-CAMP Startup]}, journal = {PLoS One}, volume = {12}, year = {2017}, month = {2017}, pages = {e0170202}, abstract = {

Short-chain dehydrogenase reductases (SDRs) have been utilized for catalyzing the reduction of many aromatic/aliphatic prochiral ketones to their respective alcohols. However, there is a paucity of data that elucidates their innate biological role and diverse substrate space. In this study, we executed an in-depth biochemical characterization and substrate space mapping (with 278 prochiral ketones) of an unannotated SDR (DHK) from Debaryomyces hansenii and compared it with structurally and functionally characterized SDR Synechococcus elongatus. PCC 7942 FabG to delineate its industrial significance. It was observed that DHK was significantly more efficient than FabG, reducing a diverse set of ketones albeit at higher conversion rates. Comparison of the FabG structure with a homology model of DHK and a docking of substrate to both structures revealed the presence of additional flexible loops near the substrate binding site of DHK. The comparative elasticity of the cofactor and substrate binding site of FabG and DHK was experimentally substantiated using differential scanning fluorimetry. It is postulated that the loop flexibility may account for the superior catalytic efficiency of DHK although the positioning of the catalytic triad is conserved.

}, issn = {1932-6203}, doi = {10.1371/journal.pone.0170202}, author = {Ghatak, Arindam and Bharatham, Nagakumar and Shanbhag, Anirudh P and Datta, Santanu and Venkatraman, Janani} }