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Salter T, Collinson I, Allen WJ. Whole Cell Luminescence-Based Screen for Inhibitors of the Bacterial Sec Machinery. Biochemistry 2024. [PMID: 39207823 DOI: 10.1021/acs.biochem.4c00264] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024]
Abstract
There is a pressing need for new antibiotics to combat rising resistance to those already in use. The bacterial general secretion (Sec) system has long been considered a good target for novel antimicrobials thanks to its irreplacable role in maintaining cell envelope integrity, yet the lack of a robust, high-throughput method to screen for Sec inhibition has so far hampered efforts to realize this potential. Here, we have adapted our recently developed in vitro assay for Sec activity─based on the split NanoLuc luciferase─to work at scale and in living cells. A simple counterscreen allows compounds that specifically target Sec to be distinguished from those with other effects on cellular function. As proof of principle, we have applied this assay to a library of 5000 compounds and identified a handful of moderately effective in vivo inhibitors of Sec. Although these hits are unlikely to be potent enough to use as a basis for drug development, they demonstrate the efficacy of the screen. We therefore anticipate that the methods presented here will be scalable to larger compound libraries, in the ultimate quest for Sec inhibitors with clinically relevant properties.
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Affiliation(s)
- Tia Salter
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - Ian Collinson
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
| | - William J Allen
- School of Biochemistry, University of Bristol, University Walk, Bristol BS8 1TD, United Kingdom
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Wannawong T, Mhuantong W, Macharoen P, Niemhom N, Sitdhipol J, Chaiyawan N, Umrung S, Tanasupawat S, Suwannarach N, Asami Y, Kuncharoen N. Comparative genomics reveals insight into the phylogeny and habitat adaptation of novel Amycolatopsis species, an endophytic actinomycete associated with scab lesions on potato tubers. FRONTIERS IN PLANT SCIENCE 2024; 15:1346574. [PMID: 38601305 PMCID: PMC11004387 DOI: 10.3389/fpls.2024.1346574] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/29/2023] [Accepted: 03/07/2024] [Indexed: 04/12/2024]
Abstract
A novel endophytic actinomycete, strain MEP2-6T, was isolated from scab tissues of potato tubers collected from Mae Fag Mai Sub-district, San Sai District, Chiang Mai Province, Thailand. Strain MEP2-6T is a gram-positive filamentous bacteria characterized by meso-diaminopimelic acid in cell wall peptidoglycan and arabinose, galactose, glucose, and ribose in whole-cell hydrolysates. Diphosphatidylglycerol, phosphatidylglycerol, phosphatidylethanolamine, and hydroxy-phosphatidylethanolamine were the major phospholipids, of which MK-9(H6) was the predominant menaquinone, whereas iso-C16:0 and iso-C15:0 were the major cellular fatty acids. The genome of the strain was 10,277,369 bp in size with a G + C content of 71.7%. The 16S rRNA gene phylogenetic and core phylogenomic analyses revealed that strain MEP2-6T was closely related to Amycolatopsis lexingtonensis NRRL B-24131T (99.4%), A. pretoriensis DSM 44654T (99.3%), and A. eburnea GLM-1T (98.9%). Notably, strain MEP2-6T displayed 91.7%, 91.8%, and 87% ANIb and 49%, 48.8%, and 35.4% dDDH to A. lexingtonensis DSM 44653T (=NRRL B-24131T), A. eburnea GLM-1T, and A. pretoriensis DSM 44654T, respectively. Based on phenotypic, chemotaxonomic, and genomic data, strain MEP2-6T could be officially assigned to a novel species within the genus Amycolatopsis, for which the name Amycolatopsis solani sp. nov. has been proposed. The type of strain is MEP2-6T (=JCM 36309T = TBRC 17632T = NBRC 116395T). Amycolatopsis solani MEP2-6T was strongly proven to be a non-phytopathogen of potato scab disease because stunting of seedlings and necrotic lesions on potato tuber slices were not observed, and there were no core biosynthetic genes associated with the BGCs of phytotoxin-inducing scab lesions. Furthermore, comparative genomics can provide a better understanding of the genetic mechanisms that enable A. solani MEP2-6T to adapt to the plant endosphere. Importantly, the strain smBGCs accommodated 33 smBGCs encoded for several bioactive compounds, which could be beneficially applied in the fields of agriculture and medicine. Consequently, strain MEP2-6T is a promising candidate as a novel biocontrol agent and antibiotic producer.
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Affiliation(s)
- Thippawan Wannawong
- Department of Plant Pathology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Wuttichai Mhuantong
- Food Biotechnology Research Team, Functional Ingredients and Food Innovation Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
- Enzyme Technology Research Team, Biorefinery and Bioproducts Technology Research Group, National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Pipat Macharoen
- Department of Plant Pathology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Nantawan Niemhom
- Microbiological and Molecular Biological Laboratory, Scientific Instruments Center, School of Science, King Mongkut’s Institute of Technology Ladkrabang, Bangkok, Thailand
| | - Jaruwan Sitdhipol
- Biodiversity Research Centre, Research and Development Group for Bio-Industries, Thailand Institute of Scientific and Technological Research, Pathum Thani, Thailand
| | - Neungnut Chaiyawan
- Biodiversity Research Centre, Research and Development Group for Bio-Industries, Thailand Institute of Scientific and Technological Research, Pathum Thani, Thailand
| | - Sarinna Umrung
- Department of Plant Pathology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Somboon Tanasupawat
- Department of Biochemistry and Microbiology, Faculty of Pharmaceutical Sciences, Chulalongkorn University, Bangkok, Thailand
| | - Nakarin Suwannarach
- Center of Excellence in Microbial Diversity and Sustainable Utilization, Chiang Mai University, Chiang Mai, Thailand
- Department of Biology, Faculty of Science, Chiang Mai University, Chiang Mai, Thailand
| | - Yukihiro Asami
- Graduate School of Infection Control Sciences, Kitasato University, Tokyo, Japan
- Ōmura Satoshi Memorial Institute, Kitasato University, Tokyo, Japan
| | - Nattakorn Kuncharoen
- Department of Plant Pathology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
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Effective Small Molecule Antibacterials from a Novel Anti-Protein Secretion Screen. Microorganisms 2021; 9:microorganisms9030592. [PMID: 33805695 PMCID: PMC8000395 DOI: 10.3390/microorganisms9030592] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 12/03/2022] Open
Abstract
The increasing problem of bacterial resistance to antibiotics underscores the urgent need for new antibacterials. Protein export pathways are attractive potential targets. The Sec pathway is essential for bacterial viability and includes components that are absent from eukaryotes. Here, we used a new high-throughput in vivo screen based on the secretion and activity of alkaline phosphatase (PhoA), a Sec-dependent secreted enzyme that becomes active in the periplasm. The assay was optimized for a luminescence-based substrate and was used to screen a ~240K small molecule compound library. After hit confirmation and analoging, 14 HTS secretion inhibitors (HSI), belonging to eight structural classes, were identified with IC50 < 60 µM. The inhibitors were evaluated as antibacterials against 19 Gram-negative and Gram-positive bacterial species (including those from the WHO’s top pathogens list). Seven of them—HSI#6, 9; HSI#1, 5, 10; and HSI#12, 14—representing three structural families, were bacteriocidal. HSI#6 was the most potent hit against 13 species of both Gram-negative and Gram-positive bacteria with IC50 of 0.4 to 8.7 μM. HSI#1, 5, 9 and 10 inhibited the viability of Gram-positive bacteria with IC50 ~6.9–77.8 μM. HSI#9, 12, and 14 inhibited the viability of E. coli strains with IC50 < 65 μM. Moreover, HSI#1, 5 and 10 inhibited the viability of an E. coli strain missing TolC to improve permeability with IC50 4 to 14 μM, indicating their inability to penetrate the outer membrane. The antimicrobial activity was not related to the inhibition of the SecA component of the translocase in vitro, and hence, HSI molecules may target new unknown components that directly or indirectly affect protein secretion. The results provided proof of the principle that the new broad HTS approach can yield attractive nanomolar inhibitors that have potential as new starting compounds for optimization to derive potential antibiotics.
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Abstract
There is a consensus in the medical profession of the pressing need for novel antimicrobial agents due to issues related to drug resistance. In practice, solutions to this problem to a large degree lie with the identification of new and vital targets in bacteria and subsequently designing their inhibitors. We consider SecA a very promising antimicrobial target. In this review, we compile and analyze information available on SecA to show that inhibition of SecA has a multitude of consequences. Furthermore, we discuss issues critical to the design and evaluation of SecA inhibitors.
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Abstract
The dramatic rise in microbial drug resistance in recent years has led to ongoing searches for novel drugs to add to the armory against infectious disease. Nevertheless, a paucity of new antibacterial drugs in discovery and development pipelines using traditional approaches has prompted a variety of unconventional and disruptive strategies for antibacterial drug discovery. Herein, we review recent nontraditional approaches that have been piloted for early drug discovery efforts. These unique methodologies open new avenues for finding the next generation of antimicrobials.
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Affiliation(s)
- Maya A Farha
- M.G. DeGroote Institute for Infectious Disease Research, and Department of Biochemistry and Biomedical Sciences, McMaster University, Ontario, Canada
| | - Eric D Brown
- M.G. DeGroote Institute for Infectious Disease Research, and Department of Biochemistry and Biomedical Sciences, McMaster University, Ontario, Canada
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Crowther GJ, Weller SM, Jones JC, Weaver T, Fan E, Van Voorhis WC, Rosen H. The Bacterial Sec Pathway of Protein Export: Screening and Follow-Up. ACTA ACUST UNITED AC 2015; 20:921-6. [PMID: 25987586 DOI: 10.1177/1087057115587458] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2015] [Accepted: 04/27/2015] [Indexed: 11/16/2022]
Abstract
Most noncytoplasmic bacterial proteins are exported through the SecYEG channel in the cytoplasmic membrane. This channel and its associated proteins, collectively referred to as the Sec pathway, have strong appeal as a possible antibiotic drug target, yet progress toward new drugs targeting this pathway has been slow, perhaps due partly to many researchers' focus on a single component, the SecA ATPase. Here we report on a pathway-based screen in which beta-galactosidase (β-gal) activity is trapped in the cytoplasm of Escherichia coli cells if translocation through SecYEG is impaired. Several hit compounds passed a counterscreen distinguishing between β-gal overexpression and impaired β-gal export. However, the most extensively characterized hit gave limited E. coli growth inhibition (EC(50) ≥ 400 µM), and growth inhibition could not be unambiguously linked to the compound's effect on the Sec pathway. Our study and others underscore the challenges of finding potent druglike hits against this otherwise promising drug target.
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Affiliation(s)
| | - Sara M Weller
- Department of Medicine, University of Washington, Seattle, WA, USA
| | - Jackson C Jones
- Department of Medicine, University of Washington, Seattle, WA, USA
| | - Tatiana Weaver
- Department of Medicine, University of Washington, Seattle, WA, USA
| | - Erkang Fan
- Department of Biochemistry, University of Washington, Seattle, WA, USA
| | | | - Henry Rosen
- Department of Medicine, University of Washington, Seattle, WA, USA
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Rao C V S, De Waelheyns E, Economou A, Anné J. Antibiotic targeting of the bacterial secretory pathway. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2014; 1843:1762-83. [PMID: 24534745 DOI: 10.1016/j.bbamcr.2014.02.004] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2013] [Revised: 01/27/2014] [Accepted: 02/06/2014] [Indexed: 02/06/2023]
Abstract
Finding new, effective antibiotics is a challenging research area driven by novel approaches required to tackle unconventional targets. In this review we focus on the bacterial protein secretion pathway as a target for eliminating or disarming pathogens. We discuss the latest developments in targeting the Sec-pathway for novel antibiotics focusing on two key components: SecA, the ATP-driven motor protein responsible for driving preproteins across the cytoplasmic membrane and the Type I signal peptidase that is responsible for the removal of the signal peptide allowing the release of the mature protein from the membrane. We take a bird's-eye view of other potential targets in the Sec-pathway as well as other Sec-dependent or Sec-independent protein secretion pathways as targets for the development of novel antibiotics. This article is part of a Special Issue entitled: Protein trafficking and secretion in bacteria. Guest Editors: Anastassios Economou and Ross Dalbey.
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Affiliation(s)
- Smitha Rao C V
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium.
| | - Evelien De Waelheyns
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium.
| | - Anastassios Economou
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium; Institute of Molecular Biology and Biotechnology, FORTH, University of Crete, P.O. Box 1385, GR-711 10 Iraklio, Crete, Greece; Department of Biology, University of Crete, P.O. Box 1385, GR-71110 Iraklio, Crete, Greece.
| | - Jozef Anné
- Laboratory of Molecular Bacteriology, Rega Institute, Department of Microbiology and Immunology, KU Leuven, O&N1, 6th floor, Herestraat 49, P.O. Box 1037, B-3000 Leuven, Belgium.
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