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Karadkhelkar NM, Gupta P, Barasa L, Chilamakuri R, Hlordzi CK, Acharekar N, Agarwal S, Chen ZS, Yoganathan S. Chemical Derivatization Leads to the Discovery Of Novel Analogs of Azotochelin, a Natural Siderophore, as Promising Anticancer Agents. ChemMedChem 2024; 19:e202300715. [PMID: 38598189 DOI: 10.1002/cmdc.202300715] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2023] [Revised: 03/21/2024] [Accepted: 04/08/2024] [Indexed: 04/11/2024]
Abstract
Siderophores are structurally unique medicinal natural products and exhibit considerable therapeutic potential. Herein, we report the design and synthesis of azotochelin, a natural siderophore, and an extensive library of azotochelin analogs and their anticancer properties. We modified the carboxylic acid and the aromatic ring of azotochelin using various chemical motifs. We evaluated the cytotoxicity of the compounds against six different cancer cell lines (KB-3-1, SNB-19, MCF-7, K-562, SW-620, and NCI-H460) and a non-cancerous cell line (HEK-293). Among the twenty compounds tested, the IC50 values of nine compounds (14, 32, 35-40, and 54) were between 0.7 and 2.0 μM against a lung cancer cell line (NCI-H460). Moreover, several compounds showed good cytotoxicity profile (IC50 <10 μM) against the tested cancer cell lines. The flow cytometry analysis showed that compounds 36 and 38 induced apoptosis in NCI-H460 in a dose-dependent manner. The cell cycle analysis indicated that compounds 36 and 38 significantly arrested the cell cycle at the S phase to block cancer cell proliferation in the NCI-H460 cell line. The study has produced various novel azotochelin analogs that are potentially effective anticancer agents and lead compounds for further synthetic and medicinal chemistry exploration.
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Affiliation(s)
- Nishant M Karadkhelkar
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY, 11439 (S.Y.)
- Current affiliation: The Scripps Research Institute, 10550 N Torrey Pines Rd., La Jolla, CA, 92037
| | - Pranav Gupta
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY, 11439 (S.Y.)
| | - Leonard Barasa
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY, 11439 (S.Y.)
- Current affiliation: Department of Biochemistry and Molecular Biotechnology, University of Massachusetts Medical School, Worcester, MA, 01605
| | - Rameswari Chilamakuri
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY, 11439 (S.Y.)
| | - Christopher K Hlordzi
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY, 11439 (S.Y.)
| | - Nikita Acharekar
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY, 11439 (S.Y.)
| | - Saurabh Agarwal
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY, 11439 (S.Y.)
| | - Zhe-Sheng Chen
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY, 11439 (S.Y.)
| | - Sabesan Yoganathan
- Department of Pharmaceutical Sciences, College of Pharmacy and Health Sciences, St. John's University, 8000 Utopia Parkway, Queens, NY, 11439 (S.Y.)
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Foshag D, Campbell C, Pawelek PD. The C-glycosyltransferase IroB from pathogenic Escherichia coli: identification of residues required for efficient catalysis. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2014; 1844:1619-30. [PMID: 24960592 DOI: 10.1016/j.bbapap.2014.06.010] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 04/22/2014] [Revised: 06/12/2014] [Accepted: 06/16/2014] [Indexed: 12/13/2022]
Abstract
Escherichia coli C-glycosyltransferase IroB catalyzes the formation of a CC bond between enterobactin and the glucose moiety of UDP-glucose, resulting in the production of mono-, di- and tri-glucosylated enterobactin (MGE, DGE, TGE). To identify catalytic residues, we generated a homology model of IroB from aligned structures of two similar C-glycosyltransferases as templates. Superposition of our homology model onto the structure of a TDP-bound orthologue revealed residue W264 as a possible stabilizer of UDP-glucose. D304 in our model was located near the predicted site of the glucose moiety of UDP-glucose. A loop containing possible catalytic residues (H65, H66, E67) was found at the predicted enterobactin-binding site. We generated IroB variants at positions 65-67, 264, and 304 and investigated variant protein conformations and enzymatic activities. Variants were found to have Tm values similar to wild-type IroB. Fluorescence emission spectra of H65A/H66A, E67A, and D304N were superimposable with wild-type IroB. However, the emission spectrum of W264L was blue-shifted, suggesting solvent exposure of W264. While H65A/H66A retained activity (92% conversion of enterobactin, with MGE as a major product), all other IroB variants were impaired in their abilities to glucosylate enterobactin: E67A catalyzed partial (29%) conversion of enterobactin to MGE; W264L converted 55% of enterobactin to MGE; D304N was completely inactive. Activity-impaired variants were found to bind enterobactin with affinities within 2.5-fold of wild-type IroB. Given our outcomes, we propose that IroB W264 and D304 are required for binding and orienting UDP-glucose, while E67, possibly supported by H65/H66, participates in enterobactin/MGE/DGE deprotonation.
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Affiliation(s)
- Daniel Foshag
- Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St. W., Montreal, Quebec H4B 1R6, Canada
| | - Cory Campbell
- Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St. W., Montreal, Quebec H4B 1R6, Canada
| | - Peter D Pawelek
- Department of Chemistry and Biochemistry, Concordia University, 7141 Sherbrooke St. W., Montreal, Quebec H4B 1R6, Canada; Groupe de Recherche Axé sur la Structure des Protéines (GRASP), Canada.
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Cisar JS, Tan DS. Small molecule inhibition of microbial natural product biosynthesis-an emerging antibiotic strategy. Chem Soc Rev 2008; 37:1320-9. [PMID: 18568158 DOI: 10.1039/b702780j] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
A variety of natural products modulate critical biological processes in the microorganisms that produce them. Thus, inhibition of the corresponding natural product biosynthesis pathways represents a promising avenue to develop novel antibiotics. In this tutorial review, we describe several recent examples of designed small molecule inhibitors of microbial natural product biosynthesis and their use in evaluating this emerging antibiotic strategy.
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Affiliation(s)
- Justin S Cisar
- Tri-Institutional Training Program in Chemical Biology, Memorial Sloan-Kettering Cancer Center, 1275 York Avenue, Box 422, New York, NY 10065, USA
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Nolan EM, Fischbach MA, Koglin A, Walsh CT. Biosynthetic tailoring of microcin E492m: post-translational modification affords an antibacterial siderophore-peptide conjugate. J Am Chem Soc 2007; 129:14336-47. [PMID: 17973380 PMCID: PMC2522288 DOI: 10.1021/ja074650f] [Citation(s) in RCA: 49] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The present work reveals that four proteins, MceCDIJ, encoded by the MccE492 gene cluster are responsible for the remarkable post-translational tailoring of microcin E492 (MccE492), an 84-residue protein toxin secreted by Klebsiella pneumonaie RYC492 that targets neighboring Gram-negative species. This modification results in attachment of a linearized and monoglycosylated derivative of enterobactin, a nonribosomal peptide and iron scavenger (siderophore), to the MccE492m C-terminus. MceC and MceD derivatize enterobactin by C-glycosylation at the C5 position of a N-(2,3-dihydroxybenzoyl)serine (DHB-Ser) moiety and regiospecific hydrolysis of an ester linkage in the trilactone scaffold, respectively. MceI and MceJ form a protein complex that attaches C-glycosylated enterobactins to the C-terminal serine residue of both a C10 model peptide and full-length MccE492. In the enzymatic product, the C-terminal serine residue is covalently attached to the C4' oxygen of the glucose moiety. Nonenzymatic and base-catalyzed migration of the peptide to the C6' position affords the C6' glycosyl ester linkage observed in the mature toxin, MccE492m, isolated from bacterial cultures.
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Affiliation(s)
- Elizabeth M. Nolan
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Michael A. Fischbach
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Alexander Koglin
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
| | - Christopher T. Walsh
- Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115
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Abstract
High-affinity iron acquisition is mediated by siderophore-dependent pathways in the majority of pathogenic and nonpathogenic bacteria and fungi. Considerable progress has been made in characterizing and understanding mechanisms of siderophore synthesis, secretion, iron scavenging, and siderophore-delivered iron uptake and its release. The regulation of siderophore pathways reveals multilayer networks at the transcriptional and posttranscriptional levels. Due to the key role of many siderophores during virulence, coevolution led to sophisticated strategies of siderophore neutralization by mammals and (re)utilization by bacterial pathogens. Surprisingly, hosts also developed essential siderophore-based iron delivery and cell conversion pathways, which are of interest for diagnostic and therapeutic studies. In the last decades, natural and synthetic compounds have gained attention as potential therapeutics for iron-dependent treatment of infections and further diseases. Promising results for pathogen inhibition were obtained with various siderophore-antibiotic conjugates acting as "Trojan horse" toxins and siderophore pathway inhibitors. In this article, general aspects of siderophore-mediated iron acquisition, recent findings regarding iron-related pathogen-host interactions, and current strategies for iron-dependent pathogen control will be reviewed. Further concepts including the inhibition of novel siderophore pathway targets are discussed.
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Affiliation(s)
- Marcus Miethke
- Philipps Universität Marburg, FB Chemie Biochemie, Hans Meerwein Strasse, D-35032 Marburg, Germany
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Somu RV, Wilson DJ, Bennett EM, Boshoff HI, Celia L, Beck BJ, Barry CE, Aldrich CC. Antitubercular nucleosides that inhibit siderophore biosynthesis: SAR of the glycosyl domain. J Med Chem 2006; 49:7623-35. [PMID: 17181146 PMCID: PMC2526467 DOI: 10.1021/jm061068d] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Tuberculosis is the leading cause of infectious disease mortality in the world by a bacterial pathogen. We previously demonstrated that a bisubstrate inhibitor of the adenylation enzyme MbtA, which is responsible for the second step of mycobactin biosynthesis, exhibited potent antitubercular activity. Here we systematically investigate the structure-activity relationships of the bisubstrate inhibitor glycosyl domain resulting in the identification of a carbocyclic analogue that possesses a KIapp value of 2.3 nM and MIC99 values of 1.56 microM against M. tuberculosis H37Rv. The SAR data suggest the intriguing possibility that the bisubstrate inhibitors utilize a transporter for entry across the mycobacterial cell envelope. Additionally, we report improved conditions for the expression of MbtA and biochemical analysis, demonstrating that MbtA follows a random sequential enzyme mechanism for the adenylation half-reaction.
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Affiliation(s)
- Ravindranadh V Somu
- Center for Drug Design, Academic Health Center, University of Minnesota, Minneapolis, MN 55455, USA
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