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Hutfless EH, Chaudhari SS, Thomas VC. Emerging Roles of Nitric Oxide Synthase in Bacterial Physiology. Adv Microb Physiol 2018; 72:147-191. [PMID: 29778214 DOI: 10.1016/bs.ampbs.2018.01.006] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Nitric oxide (NO) is a potent inhibitor of diverse cellular processes in bacteria. Therefore, it was surprising to discover that several bacterial species, primarily Gram-positive organisms, harboured a gene encoding nitric oxide synthase (NOS). Recent attempts to characterize bacterial NOS (bNOS) have resulted in the discovery of structural features that may allow it to function as a NO dioxygenase and produce nitrate in addition to NO. Consistent with this characterization, investigations into the biological function of bNOS have also emphasized a role for NOS-dependent nitrate and nitrite production in aerobic and microaerobic respiration. In this review, we aim to compare, contrast, and summarize the structure, biochemistry, and biological role of bNOS with mammalian NOS and discuss how recent advances in our understanding of bNOS have enabled efforts at designing inhibitors against it.
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Affiliation(s)
| | | | - Vinai C Thomas
- University of Nebraska Medical Center, Omaha, NE, United States.
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Poulos TL, Li H. Nitric oxide synthase and structure-based inhibitor design. Nitric Oxide 2016; 63:68-77. [PMID: 27890696 DOI: 10.1016/j.niox.2016.11.004] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 11/09/2016] [Accepted: 11/21/2016] [Indexed: 11/24/2022]
Abstract
Once it was discovered that the enzyme nitric oxide synthase (NOS) is responsible for the biosynthesis of NO, NOS became a drug target. Particularly important is the over production of NO by neuronal NOS (nNOS) in various neurodegenerative disorders. After the various NOS isoforms were identified, inhibitor development proceeded rapidly. It soon became evident, however, that isoform selectivity presents a major challenge. All 3 human NOS isoforms, nNOS, eNOS (endothelial NOS), and iNOS (inducible NOS) have nearly identical active site structures thus making selective inhibitor design especially difficult. Of particular importance is the avoidance of inhibiting eNOS owing to its vital role in the cardiovascular system. This review summarizes some of the history of NOS inhibitor development and more recent advances in developing isoform selective inhibitors using primarily structure-based approaches.
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Affiliation(s)
- Thomas L Poulos
- Departments of Molecular Biology & Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, Irvine, CA 92697-3900, USA.
| | - Huiying Li
- Departments of Molecular Biology & Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, Irvine, CA 92697-3900, USA
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Holden JK, Kang S, Beasley FC, Cinelli MA, Li H, Roy SG, Dejam D, Edinger AL, Nizet V, Silverman RB, Poulos TL. Nitric Oxide Synthase as a Target for Methicillin-Resistant Staphylococcus aureus. ACTA ACUST UNITED AC 2016; 22:785-92. [PMID: 26091171 DOI: 10.1016/j.chembiol.2015.05.013] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 04/20/2015] [Accepted: 05/17/2015] [Indexed: 02/04/2023]
Abstract
Bacterial infections associated with methicillin-resistant Staphylococcus aureus (MRSA) are a major economic burden to hospitals, and confer high rates of morbidity and mortality among those infected. Exploitation of novel therapeutic targets is thus necessary to combat this dangerous pathogen. Here, we report on the identification and characterization, including crystal structures, of two nitric oxide synthase (NOS) inhibitors that function as antimicrobials against MRSA. These data provide the first evidence that bacterial NOS (bNOS) inhibitors can work synergistically with oxidative stress to enhance MRSA killing. Crystal structures show that each inhibitor contacts an active site Ile residue in bNOS that is Val in the mammalian NOS isoforms. Mutagenesis studies show that the additional nonpolar contacts provided by the Ile in bNOS contribute to tighter binding toward the bacterial enzyme.
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Affiliation(s)
- Jeffrey K Holden
- Departments of Molecular Biology and Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, CA 92697-3900, USA
| | - Soosung Kang
- Departments of Chemistry and Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, IL 60208-3113, USA
| | - Federico C Beasley
- Departments of Pediatrics and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, CA 92093, USA
| | - Maris A Cinelli
- Departments of Chemistry and Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, IL 60208-3113, USA
| | - Huiying Li
- Departments of Molecular Biology and Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, CA 92697-3900, USA
| | - Saurabh G Roy
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA
| | - Dillon Dejam
- Departments of Molecular Biology and Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, CA 92697-3900, USA
| | - Aimee L Edinger
- Department of Developmental and Cell Biology, University of California, Irvine, CA 92697, USA
| | - Victor Nizet
- Departments of Pediatrics and Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California, San Diego, CA 92093, USA
| | - Richard B Silverman
- Departments of Chemistry and Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, IL 60208-3113, USA.
| | - Thomas L Poulos
- Departments of Molecular Biology and Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, CA 92697-3900, USA.
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Kang S, Li H, Tang W, Martásek P, Roman LJ, Poulos TL, Silverman RB. 2-Aminopyridines with a Truncated Side Chain To Improve Human Neuronal Nitric Oxide Synthase Inhibitory Potency and Selectivity. J Med Chem 2015; 58:5548-60. [PMID: 26120733 PMCID: PMC4514563 DOI: 10.1021/acs.jmedchem.5b00573] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
We have analyzed a recently obtained crystal structure of human neuronal nitric oxide synthase (nNOS) and then designed and synthesized several 2-aminopyridine derivatives containing a truncated side chain to avoid the hydrophobic pocket that differentiates human and rat nNOS in an attempt to explore alternative binding poses along the substrate access channel of human nNOS. Introduction of an N-methylethane-1,2-diamine side chain and conformational constraints such as benzonitrile and pyridine as the middle aromatic linker were sufficient to increase human and rat nNOS binding affinity and inducible and endothelial NOS selectivity. We found that 14b is a potent inhibitor; the binding modes with human and rat nNOS are unexpected, inducing side chain rotamer changes in Gln478 (rat) at the top of the active site. Compound 19c exhibits Ki values of 24 and 55 nM for rat and human nNOS, respectively, with 153-fold iNOS and 1040-fold eNOS selectivity. 19c has 18% oral bioavailability.
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Affiliation(s)
- Soosung Kang
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
- New Drug Development Center, DGMIF, 80 Cheombok-ro, Dae-gu, Korea
| | - Huiying Li
- Departments of Molecular Biology and Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, California 92697-3900, United States
| | - Wei Tang
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
| | - Pavel Martásek
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78384-7760, United States
| | - Linda J. Roman
- Department of Biochemistry, University of Texas Health Science Center, San Antonio, Texas 78384-7760, United States
| | - Thomas L. Poulos
- Departments of Molecular Biology and Biochemistry, Pharmaceutical Sciences, and Chemistry, University of California, Irvine, California 92697-3900, United States
| | - Richard B. Silverman
- Department of Chemistry, Department of Molecular Biosciences, Chemistry of Life Processes Institute, Center for Molecular Innovation and Drug Discovery, Northwestern University, 2145 Sheridan Road, Evanston, Illinois 60208-3113, United States
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Holden JK, Dejam D, Lewis MC, Huang H, Kang S, Jing Q, Xue F, Silverman RB, Poulos TL. Inhibitor Bound Crystal Structures of Bacterial Nitric Oxide Synthase. Biochemistry 2015; 54:4075-82. [PMID: 26062720 DOI: 10.1021/acs.biochem.5b00431] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Nitric oxide generated by bacterial nitric oxide synthase (NOS) increases the susceptibility of Gram-positive pathogens Staphylococcus aureus and Bacillus anthracis to oxidative stress, including antibiotic-induced oxidative stress. Not surprisingly, NOS inhibitors also improve the effectiveness of antimicrobials. Development of potent and selective bacterial NOS inhibitors is complicated by the high active site sequence and structural conservation shared with the mammalian NOS isoforms. To exploit bacterial NOS for the development of new therapeutics, recognition of alternative NOS surfaces and pharmacophores suitable for drug binding is required. Here, we report on a wide number of inhibitor-bound bacterial NOS crystal structures to identify several compounds that interact with surfaces unique to the bacterial NOS. Although binding studies indicate that these inhibitors weakly interact with the NOS active site, many of the inhibitors reported here provide a revised structural framework for the development of new antimicrobials that target bacterial NOS. In addition, mutagenesis studies reveal several key residues that unlock access to bacterial NOS surfaces that could provide the selectivity required to develop potent bacterial NOS inhibitors.
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Affiliation(s)
- Jeffrey K Holden
- Departments of †Molecular Biology and Biochemistry, ‡Pharmaceutical Sciences, and §Chemistry, University of California, Irvine, California 92697-3900, United States.,∥Departments of Chemistry and Molecular Biosciences, ⊥Chemistry of Life Processes Institute, #Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Dillon Dejam
- Departments of †Molecular Biology and Biochemistry, ‡Pharmaceutical Sciences, and §Chemistry, University of California, Irvine, California 92697-3900, United States.,∥Departments of Chemistry and Molecular Biosciences, ⊥Chemistry of Life Processes Institute, #Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Matthew C Lewis
- Departments of †Molecular Biology and Biochemistry, ‡Pharmaceutical Sciences, and §Chemistry, University of California, Irvine, California 92697-3900, United States.,∥Departments of Chemistry and Molecular Biosciences, ⊥Chemistry of Life Processes Institute, #Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - He Huang
- Departments of †Molecular Biology and Biochemistry, ‡Pharmaceutical Sciences, and §Chemistry, University of California, Irvine, California 92697-3900, United States.,∥Departments of Chemistry and Molecular Biosciences, ⊥Chemistry of Life Processes Institute, #Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Soosung Kang
- Departments of †Molecular Biology and Biochemistry, ‡Pharmaceutical Sciences, and §Chemistry, University of California, Irvine, California 92697-3900, United States.,∥Departments of Chemistry and Molecular Biosciences, ⊥Chemistry of Life Processes Institute, #Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Qing Jing
- Departments of †Molecular Biology and Biochemistry, ‡Pharmaceutical Sciences, and §Chemistry, University of California, Irvine, California 92697-3900, United States.,∥Departments of Chemistry and Molecular Biosciences, ⊥Chemistry of Life Processes Institute, #Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Fengtian Xue
- Departments of †Molecular Biology and Biochemistry, ‡Pharmaceutical Sciences, and §Chemistry, University of California, Irvine, California 92697-3900, United States.,∥Departments of Chemistry and Molecular Biosciences, ⊥Chemistry of Life Processes Institute, #Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Richard B Silverman
- Departments of †Molecular Biology and Biochemistry, ‡Pharmaceutical Sciences, and §Chemistry, University of California, Irvine, California 92697-3900, United States.,∥Departments of Chemistry and Molecular Biosciences, ⊥Chemistry of Life Processes Institute, #Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, Illinois 60208-3113, United States
| | - Thomas L Poulos
- Departments of †Molecular Biology and Biochemistry, ‡Pharmaceutical Sciences, and §Chemistry, University of California, Irvine, California 92697-3900, United States.,∥Departments of Chemistry and Molecular Biosciences, ⊥Chemistry of Life Processes Institute, #Center for Molecular Innovation and Drug Discovery, Northwestern University, Evanston, Illinois 60208-3113, United States
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