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Singh A, Ottavi S, Krieger I, Planck K, Perkowski A, Kaneko T, Davis AM, Suh C, Zhang D, Goullieux L, Alex A, Roubert C, Gardner M, Preston M, Smith DM, Ling Y, Roberts J, Cautain B, Upton A, Cooper CB, Serbina N, Tanvir Z, Mosior J, Ouerfelli O, Yang G, Gold BS, Rhee KY, Sacchettini JC, Fotouhi N, Aubé J, Nathan C. Redirecting raltitrexed from cancer cell thymidylate synthase to Mycobacterium tuberculosis phosphopantetheinyl transferase. SCIENCE ADVANCES 2024; 10:eadj6406. [PMID: 38489355 PMCID: PMC10942122 DOI: 10.1126/sciadv.adj6406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2023] [Accepted: 02/09/2024] [Indexed: 03/17/2024]
Abstract
There is a compelling need to find drugs active against Mycobacterium tuberculosis (Mtb). 4'-Phosphopantetheinyl transferase (PptT) is an essential enzyme in Mtb that has attracted interest as a potential drug target. We optimized a PptT assay, used it to screen 422,740 compounds, and identified raltitrexed, an antineoplastic antimetabolite, as the most potent PptT inhibitor yet reported. While trying unsuccessfully to improve raltitrexed's ability to kill Mtb and remove its ability to kill human cells, we learned three lessons that may help others developing antibiotics. First, binding of raltitrexed substantially changed the configuration of the PptT active site, complicating molecular modeling of analogs based on the unliganded crystal structure or the structure of cocrystals with inhibitors of another class. Second, minor changes in the raltitrexed molecule changed its target in Mtb from PptT to dihydrofolate reductase (DHFR). Third, the structure-activity relationship for over 800 raltitrexed analogs only became interpretable when we quantified and characterized the compounds' intrabacterial accumulation and transformation.
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Affiliation(s)
- Amrita Singh
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York 10021, USA
| | - Samantha Ottavi
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Inna Krieger
- Department of Biochemistry and Biophysics, Texas Agricultural and Mechanical University, College Station, TX 77843, USA
| | - Kyle Planck
- Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - Andrew Perkowski
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Takushi Kaneko
- Global Alliance for TB Drug Development, New York, NY 10005, USA
| | | | - Christine Suh
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York 10021, USA
| | - David Zhang
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York 10021, USA
| | | | - Alexander Alex
- AMG Consultants Limited, Camburgh House, 27 New Dover Road, Canterbury, Kent, CT1 3DN, UK
- Evenor Consulting Limited, The New Barn, Mill Lane, Eastry, Kent CT13 0JW, UK
| | | | - Mark Gardner
- AMG Consultants Limited, Camburgh House, 27 New Dover Road, Canterbury, Kent, CT1 3DN, UK
| | - Marian Preston
- Discovery Sciences, R&D, AstraZeneca, Cambridge CB4 0WG, UK
| | - Dave M. Smith
- Discovery Sciences, R&D, AstraZeneca, Cambridge CB4 0WG, UK
| | - Yan Ling
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York 10021, USA
| | - Julia Roberts
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York 10021, USA
| | - Bastien Cautain
- Evotec ID (Lyon), SAS 40 Avenue Tony Garnier, Lyon 69001, France
| | - Anna Upton
- Evotec ID (Lyon), SAS 40 Avenue Tony Garnier, Lyon 69001, France
| | | | - Natalya Serbina
- Global Alliance for TB Drug Development, New York, NY 10005, USA
| | - Zaid Tanvir
- Global Alliance for TB Drug Development, New York, NY 10005, USA
| | - John Mosior
- Department of Biochemistry and Biophysics, Texas Agricultural and Mechanical University, College Station, TX 77843, USA
| | - Ouathek Ouerfelli
- Organic Synthesis Core, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Guangli Yang
- Organic Synthesis Core, Memorial Sloan Kettering Cancer Center, New York, NY 10065, USA
| | - Ben S. Gold
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York 10021, USA
| | - Kyu Y. Rhee
- Department of Medicine, Weill Cornell Medicine, New York, NY 10021, USA
| | - James C. Sacchettini
- Department of Biochemistry and Biophysics, Texas Agricultural and Mechanical University, College Station, TX 77843, USA
| | - Nader Fotouhi
- Global Alliance for TB Drug Development, New York, NY 10005, USA
| | - Jeffrey Aubé
- Division of Chemical Biology and Medicinal Chemistry, UNC Eshelman School of Pharmacy, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
| | - Carl Nathan
- Department of Microbiology and Immunology, Weill Cornell Medicine, New York, New York 10021, USA
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Gutiérrez S, Wellman GB, Lauersen KJ. Teaching an old ‘doc’ new tricks for algal biotechnology: Strategic filter use enables multi-scale fluorescent protein signal detection. Front Bioeng Biotechnol 2022; 10:979607. [PMID: 36213064 PMCID: PMC9540369 DOI: 10.3389/fbioe.2022.979607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Accepted: 08/25/2022] [Indexed: 11/13/2022] Open
Abstract
Fluorescent proteins (FPs) are powerful reporters with a broad range of applications in gene expression and subcellular localization. High-throughput screening is often required to identify individual transformed cell lines in organisms that favor non-homologous-end-joining integration of transgenes into genomes, like in the model green microalga Chlamydomonas reinhardtii. Strategic transgene design, including genetic fusion of transgenes to FPs, and strain domestication have aided engineering efforts in this host but have not removed the need for screening large numbers of transformants to identify those with robust transgene expression levels. FPs facilitate transformant screening by providing a visual signal indicating transgene expression. However, limited combinations of FPs have been described in alga and inherent background fluorescence from cell pigments can hinder FP detection efforts depending on available infrastructure. Here, an updated set of algal nuclear genome-domesticated plasmid parts for seven FPs and six epitope tags were generated and tested in C. reinhardtii. Strategic filter selection was found to enable detection of up to five independent FPs signals from cyan to far-red separately from inherent chlorophyll fluorescence in live algae at the agar plate-level and also in protein electrophoresis gels. This work presents technical advances for algal engineering that can assist reporter detection efforts in other photosynthetic host cells or organisms with inherent background fluorescence.
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