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Das S, Pattanayakanahalli Henjarappa K, Mahanta N. Enzymatic reconstitution of salicylate formation in promysalin biosynthesis. Bioorg Med Chem Lett 2023; 94:129440. [PMID: 37567320 DOI: 10.1016/j.bmcl.2023.129440] [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: 05/25/2023] [Revised: 08/02/2023] [Accepted: 08/08/2023] [Indexed: 08/13/2023]
Abstract
Promysalin is an amphipathic antibiotic isolated from Pseudomonas promysalinigenes (previously Pseudomonas putida RW10S1) which shows potent antibacterial activities against Gram-negative pathogens by inactivating succinate dehydrogenase. Based on the in-vivo studies, promysalin is hypothesized to be assembled from three building blocks: salicylic acid, proline, and myristic acid via a proposed but uncharacterized hybrid NRPS-PKS biosynthetic pathway. So far, no in-vitro biosynthetic studies have been reported for this promising antibiotic. Here, we report the first in-vitro reconstitution and biochemical characterization of two early enzymes on the pathway: PpgH, an isochorismate synthase (IS), and PpgG, an isochorismate pyruvate lyase (IPL) which are involved in the biosynthesis of salicylic acid, the polar fragment of promysalin. We also report a secondary chorismate mutase (CM) activity for PpgG. Based on our biochemical experiments, preliminary mechanistic proposals have been postulated for PpgH and PpgG. We believe this study will lay a strong foundation for elucidating the functions and mechanisms of other intriguing enzymes of the promysalin biosynthesis pathway, which may potentially unravel interesting enzyme chemistries and promote pathway engineering in the future.
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Affiliation(s)
- Simita Das
- Department of Chemistry, Indian Institute of Technology Dharwad, Karnataka 580011, India
| | | | - Nilkamal Mahanta
- Department of Chemistry, Indian Institute of Technology Dharwad, Karnataka 580011, India.
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2
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Stelitano G, Cocorullo M, Mori M, Villa S, Meneghetti F, Chiarelli LR. Iron Acquisition and Metabolism as a Promising Target for Antimicrobials (Bottlenecks and Opportunities): Where Do We Stand? Int J Mol Sci 2023; 24:ijms24076181. [PMID: 37047161 PMCID: PMC10094389 DOI: 10.3390/ijms24076181] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2023] [Revised: 03/21/2023] [Accepted: 03/23/2023] [Indexed: 03/29/2023] Open
Abstract
The emergence of multidrug-resistant (MDR) and extensively drug-resistant (XDR) infections is one of the most crucial challenges currently faced by the scientific community. Developments in the fundamental understanding of their underlying mechanisms may open new perspectives in drug discovery. In this review, we conducted a systematic literature search in PubMed, Web of Science, and Scopus, to collect information on innovative strategies to hinder iron acquisition in bacteria. In detail, we discussed the most interesting targets from iron uptake and metabolism pathways, and examined the main chemical entities that exhibit anti-infective activities by interfering with their function. The mechanism of action of each drug candidate was also reviewed, together with its pharmacodynamic, pharmacokinetic, and toxicological properties. The comprehensive knowledge of such an impactful area of research will hopefully reflect in the discovery of newer antibiotics able to effectively tackle the antimicrobial resistance issue.
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Mishra AK, Baek KH. Salicylic Acid Biosynthesis and Metabolism: A Divergent Pathway for Plants and Bacteria. Biomolecules 2021; 11:705. [PMID: 34065121 PMCID: PMC8150894 DOI: 10.3390/biom11050705] [Citation(s) in RCA: 31] [Impact Index Per Article: 10.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Revised: 05/06/2021] [Accepted: 05/06/2021] [Indexed: 01/24/2023] Open
Abstract
Salicylic acid (SA) is an active secondary metabolite that occurs in bacteria, fungi, and plants. SA and its derivatives (collectively called salicylates) are synthesized from chorismate (derived from shikimate pathway). SA is considered an important phytohormone that regulates various aspects of plant growth, environmental stress, and defense responses against pathogens. Besides plants, a large number of bacterial species, such as Pseudomonas, Bacillus, Azospirillum, Salmonella, Achromobacter, Vibrio, Yersinia, and Mycobacteria, have been reported to synthesize salicylates through the NRPS/PKS biosynthetic gene clusters. This bacterial salicylate production is often linked to the biosynthesis of small ferric-ion-chelating molecules, salicyl-derived siderophores (known as catecholate) under iron-limited conditions. Although bacteria possess entirely different biosynthetic pathways from plants, they share one common biosynthetic enzyme, isochorismate synthase, which converts chorismate to isochorismate, a common precursor for synthesizing SA. Additionally, SA in plants and bacteria can undergo several modifications to carry out their specific functions. In this review, we will systematically focus on the plant and bacterial salicylate biosynthesis and its metabolism.
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Affiliation(s)
| | - Kwang-Hyun Baek
- Department of Biotechnology, Yeungnam University, Gyeongsan 38541, Gyeongbuk, Korea;
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Shelton CL, Lamb AL. Unraveling the Structure and Mechanism of the MST(ery) Enzymes. Trends Biochem Sci 2018; 43:342-357. [PMID: 29573882 DOI: 10.1016/j.tibs.2018.02.011] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 02/23/2018] [Accepted: 02/27/2018] [Indexed: 01/06/2023]
Abstract
The menaquinone, siderophore, and tryptophan (MST) enzymes transform chorismate to generate precursor molecules for the biosynthetic pathways defined in their name. Kinetic data, both steady-state and transient-state, and X-ray crystal structures indicate that these enzymes are highly conserved both in mechanism and in structure. Because these enzymes are found in pathogens but not in humans, there is considerable interest in these enzymes as drug design targets. While great progress has been made in defining enzyme structure and mechanism, inhibitor design has lagged behind. This review provides a detailed description of the evidence that begins to unravel the mystery of how the MST enzymes work, and how that information has been used in inhibitor design.
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Affiliation(s)
- Catherine L Shelton
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA
| | - Audrey L Lamb
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA.
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Martín del Campo JS, Vogelaar N, Tolani K, Kizjakina K, Harich K, Sobrado P. Inhibition of the Flavin-Dependent Monooxygenase Siderophore A (SidA) Blocks Siderophore Biosynthesis and Aspergillus fumigatus Growth. ACS Chem Biol 2016; 11:3035-3042. [PMID: 27588426 DOI: 10.1021/acschembio.6b00666] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Aspergillus fumigatus is an opportunistic fungal pathogen and the most common causative agent of fatal invasive mycoses. The flavin-dependent monooxygenase siderophore A (SidA) catalyzes the oxygen and NADPH dependent hydroxylation of l-ornithine (l-Orn) to N5-l-hydroxyornithine in the biosynthetic pathway of hydroxamate-containing siderophores in A. fumigatus. Deletion of the gene that codes for SidA has shown that it is essential in establishing infection in mice models. Here, a fluorescence polarization high-throughput assay was used to screen a 2320 compound library for inhibitors of SidA. Celastrol, a natural quinone methide, was identified as a noncompetitive inhibitor of SidA with a MIC value of 2 μM. Docking experiments suggest that celastrol binds across the NADPH and l-Orn pocket. Celastrol prevents A. fumigatus growth in blood agar. The addition of purified ferric-siderophore abolished the inhibitory effect of celastrol. Thus, celastrol inhibits A. fumigatus growth by blocking siderophore biosynthesis through SidA inhibiton.
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Affiliation(s)
| | - Nancy Vogelaar
- Virginia
Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Karishma Tolani
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Karina Kizjakina
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Kim Harich
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
| | - Pablo Sobrado
- Department
of Biochemistry, Virginia Tech, Blacksburg, Virginia 24061, United States
- Virginia
Tech Center for Drug Discovery, Virginia Tech, Blacksburg, Virginia 24061, United States
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Meneely KM, Sundlov JA, Gulick AM, Moran GR, Lamb AL. An Open and Shut Case: The Interaction of Magnesium with MST Enzymes. J Am Chem Soc 2016; 138:9277-93. [PMID: 27373320 PMCID: PMC5029964 DOI: 10.1021/jacs.6b05134] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
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The shikimate pathway of bacteria,
fungi, and plants generates
chorismate, which is drawn into biosynthetic pathways that form aromatic
amino acids and other important metabolites, including folates, menaquinone,
and siderophores. Many of the pathways initiated at this branch point
transform chorismate using an MST enzyme. The MST enzymes (menaquinone, siderophore, and tryptophan biosynthetic enzymes) are structurally homologous and magnesium-dependent,
and all perform similar chemical permutations to chorismate by nucleophilic
addition (hydroxyl or amine) at the 2-position of the ring, inducing
displacement of the 4-hydroxyl. The isomerase enzymes release isochorismate
or aminodeoxychorismate as the product, while the synthase enzymes
also have lyase activity that displaces pyruvate to form either salicylate
or anthranilate. This has led to the hypothesis that the isomerase
and lyase activities performed by the MST enzymes are functionally
conserved. Here we have developed tailored pre-steady-state approaches
to establish the kinetic mechanisms of the isochorismate and salicylate
synthase enzymes of siderophore biosynthesis. Our data are centered
on the role of magnesium ions, which inhibit the isochorismate synthase
enzymes but not the salicylate synthase enzymes. Prior structural
data have suggested that binding of the metal ion occludes access
or egress of substrates. Our kinetic data indicate that for the production
of isochorismate, a high magnesium ion concentration suppresses the
rate of release of product, accounting for the observed inhibition
and establishing the basis of the ordered-addition kinetic mechanism.
Moreover, we show that isochorismate is channeled through the synthase
reaction as an intermediate that is retained in the active site by
the magnesium ion. Indeed, the lyase-active enzyme has 3 orders of
magnitude higher affinity for the isochorismate complex relative to
the chorismate complex. Apparent negative-feedback inhibition by ferrous
ions is documented at nanomolar concentrations, which is a potentially
physiologically relevant mode of regulation for siderophore biosynthesis
in vivo.
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Affiliation(s)
- Kathleen M Meneely
- Department of Molecular Biosciences, University of Kansas , Lawrence, Kansas 66045, United States
| | - Jesse A Sundlov
- Hauptman-Woodward Medical Research Institute , 700 Ellicott Street, Buffalo, New York 14203, United States
| | - Andrew M Gulick
- Hauptman-Woodward Medical Research Institute , 700 Ellicott Street, Buffalo, New York 14203, United States
| | - Graham R Moran
- Department of Chemistry and Biochemistry, University of Wisconsin-Milwaukee , Milwaukee, Wisconsin 53201, United States
| | - Audrey L Lamb
- Department of Molecular Biosciences, University of Kansas , Lawrence, Kansas 66045, United States
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Lamb AL. Breaking a pathogen's iron will: Inhibiting siderophore production as an antimicrobial strategy. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2015; 1854:1054-70. [PMID: 25970810 DOI: 10.1016/j.bbapap.2015.05.001] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2015] [Revised: 04/29/2015] [Accepted: 05/06/2015] [Indexed: 12/24/2022]
Abstract
The rise of antibiotic resistance is a growing public health crisis. Novel antimicrobials are sought, preferably developing nontraditional chemical scaffolds that do not inhibit standard targets such as cell wall synthesis or the ribosome. Iron scavenging has been proposed as a viable target, because bacterial and fungal pathogens must overcome the nutritional immunity of the host to be virulent. This review highlights the recent work toward exploiting the biosynthetic enzymes of siderophore production for the design of next generation antimicrobials.
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Affiliation(s)
- Audrey L Lamb
- Department of Molecular Biosciences, University of Kansas, Lawrence, KS 66045, USA.
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