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Zhao Y, Xu G, Xu Z, Guo B, Liu F. LexR Positively Regulates the LexABC Efflux Pump Involved in Self-Resistance to the Antimicrobial Di- N-Oxide Phenazine in Lysobacter antibioticus. Microbiol Spectr 2023; 11:e0487222. [PMID: 37166326 PMCID: PMC10269722 DOI: 10.1128/spectrum.04872-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 04/21/2023] [Indexed: 05/12/2023] Open
Abstract
Myxin, a di-N-oxide phenazine isolated from the soil bacterium Lysobacter antibioticus, exhibits potent activity against various microorganisms and has the potential to be developed as an agrochemical. Antibiotic-producing microorganisms have developed self-resistance mechanisms to protect themselves from autotoxicity. Antibiotic efflux is vital for such protection. Recently, we identified a resistance-nodulation-division (RND) efflux pump, LexABC, involved in self-resistance against myxin in L. antibioticus. Expression of its genes, lexABC, was induced by myxin and was positively regulated by the LysR family transcriptional regulator LexR. The molecular mechanisms, however, have not been clear. Here, LexR was found to bind to the lexABC promoter region to directly regulate expression. Moreover, myxin enhanced this binding. Molecular docking and surface plasmon resonance analysis showed that myxin bound LexR with valine and lysine residues at positions 146 (V146) and 195 (K195), respectively. Furthermore, mutation of K195 in vivo led to downregulation of the gene lexA. These results indicated that LexR sensed and bound with myxin, thereby directly activating the expression of the LexABC efflux pump and increasing L. antibioticus resistance against myxin. IMPORTANCE Antibiotic-producing bacteria exhibit various sophisticated mechanisms for self-protection against their own secondary metabolites. RND efflux pumps that eliminate antibiotics from cells are ubiquitous in Gram-negative bacteria. Myxin is a heterocyclic N-oxide phenazine with potent antimicrobial and antitumor activities produced by the soil bacterium L. antibioticus. The RND pump LexABC contributes to the self-resistance of L. antibioticus against myxin. Herein, we report a mechanism involving the LysR family regulator LexR that binds to myxin and directly activates the LexABC pump. Further study on self-resistance mechanisms could help the investigation of strategies to deal with increasing bacterial antibiotic resistance and enable the discovery of novel natural products with resistance genes as selective markers.
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Affiliation(s)
- Yangyang Zhao
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China
- School of Plant Protection, Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou, China
| | - Gaoge Xu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China
| | - Zhizhou Xu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China
- College of Plant Protection, Key Laboratory of Integrated Management of Crop Diseases and Pests, Nanjing Agricultural University, Nanjing, China
| | - Baodian Guo
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China
| | - Fengquan Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety, State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China
- School of Plant Protection, Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou, China
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2
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Nemeikaitė-Čėnienė A, Haberkant P, Kučiauskas D, Stein F, Čėnas N. Redox Proteomic Profile of Tirapazamine-Resistant Murine Hepatoma Cells. Int J Mol Sci 2023; 24:ijms24076863. [PMID: 37047836 PMCID: PMC10094930 DOI: 10.3390/ijms24076863] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2023] [Revised: 03/28/2023] [Accepted: 04/04/2023] [Indexed: 04/14/2023] Open
Abstract
3-Amino-1,2,4-benzotriazine-1,4-dioxide (tirapazamine, TPZ) and other heteroaromatic N-oxides (ArN→O) exhibit tumoricidal, antibacterial, and antiprotozoal activities. Their action is attributed to the enzymatic single-electron reduction to free radicals that initiate the prooxidant processes. In order to clarify the mechanisms of aerobic mammalian cytotoxicity of ArN→O, we derived a TPZ-resistant subline of murine hepatoma MH22a cells (resistance index, 5.64). The quantitative proteomic of wild-type and TPZ-resistant cells revealed 5818 proteins, of which 237 were up- and 184 down-regulated. The expression of the antioxidant enzymes aldehyde- and alcohol dehydrogenases, carbonyl reductases, catalase, and glutathione reductase was increased 1.6-5.2 times, whereas the changes in the expression of glutathione peroxidase, superoxide dismutase, thioredoxin reductase, and peroxiredoxins were less pronounced. The expression of xenobiotics conjugating glutathione-S-transferases was increased by 1.6-2.6 times. On the other hand, the expression of NADPH:cytochrome P450 reductase was responsible for the single-electron reduction in TPZ and for the 2.1-fold decrease. These data support the fact that the main mechanism of action of TPZ under aerobic conditions is oxidative stress. The unchanged expression of intranuclear antioxidant proteins peroxiredoxin, glutaredoxin, and glutathione peroxidase, and a modest increase in the expression of DNA damage repair proteins, tend to support non-site-specific but not intranuclear oxidative stress as a main factor of TPZ aerobic cytotoxicity.
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Affiliation(s)
- Aušra Nemeikaitė-Čėnienė
- State Research Institute Center for Innovative Medicine, Santariškių St. 5, LT-08406 Vilnius, Lithuania
| | - Per Haberkant
- Proteomics Core Facility EMBL Heidelberg, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Dalius Kučiauskas
- Department of Xenobiotics Biochemistry, Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania
| | - Frank Stein
- Proteomics Core Facility EMBL Heidelberg, Meyerhofstrasse 1, 69117 Heidelberg, Germany
| | - Narimantas Čėnas
- Department of Xenobiotics Biochemistry, Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania
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3
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Alatawneh N, Meijler MM. Unraveling the Antibacterial and Iron Chelating Activity of
N
‐Oxide Hydroxy‐Phenazine natural Products and Synthetic Analogs against
Staphylococcus Aureus. Isr J Chem 2023. [DOI: 10.1002/ijch.202200112] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/08/2023]
Affiliation(s)
- Nadeem Alatawneh
- Department of Chemistry and The National Institute for Biotechnology in the Negev Ben-Gurion University of the Negev Be'er Sheva 84105 Israel
| | - Michael M. Meijler
- Department of Chemistry and The National Institute for Biotechnology in the Negev Ben-Gurion University of the Negev Be'er Sheva 84105 Israel
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4
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Pyocyanin and 1-Hydroxyphenazine Promote Anaerobic Killing of Pseudomonas aeruginosa via Single-Electron Transfer with Ferrous Iron. Microbiol Spectr 2022; 10:e0231222. [PMID: 36321913 PMCID: PMC9769500 DOI: 10.1128/spectrum.02312-22] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Previously, it was reported that natural phenazines are able to support the anaerobic survival of Pseudomonas aeruginosa PA14 cells via electron shuttling, with electrodes poised as the terminal oxidants (Y. Wang, S. E. Kern, and D. K. Newman, J Bacteriol 192:365-369, 2010, https://doi.org/10.1128/JB.01188-09). The present study shows that both pyocyanin (PYO) and 1-hydroxyphenazine (1-OHPHZ) promoted the anaerobic killing of PA14 Δphz cells presumably via a single-electron transfer reaction with ferrous iron. However, phenazine-1-carboxylic acid (PCA) did not affect anaerobic survival in the presence of ferrous iron. Anaerobic cell death was alleviated by the addition of antioxidant compounds, which inhibit electron transfer via DNA damage. Neither superoxide dismutase (SOD) nor catalase was able to alleviate P. aeruginosa cell death, ruling out the possibility of reactive oxygen species (ROS)-induced killing. Further, the phenazine degradation profile and the redox state-associated color changes suggested that phenazine radical intermediates are likely generated by single-electron transfer. In this study, we showed that the phenazines 1-OHPHZ and PYO anaerobically killed the cell via single-electron transfer with ferrous iron and that the killing might have resulted from phenazine radicals. IMPORTANCE Pseudomonas aeruginosa is an opportunistic human pathogen which infects patients with burns, immunocompromised individuals, and in particular, the mucus that accumulates on the surface of the lung in cystic fibrosis (CF) patients. Phenazines as redox-active small molecules have been reported as important compounds for the control of cellular functions and virulence as well as anaerobic survival via electron shuttles. We show that both pyocyanin (PYO) and 1-hydroxyphenazine (1-OHPHZ) generate phenazine radical intermediates via presumably single-electron transfer reaction with ferrous iron, leading to the anaerobic killing of Pseudomonas cells. The recA mutant defect in the DNA repair system was more sensitive to anaerobic conditions. Our results collectively suggest that both phenazines anaerobically kill cells via DNA damage during electron transfer with iron.
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5
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Yue H, Miller AL, Khetrapal V, Jayaseker V, Wright S, Du L. Biosynthesis, regulation, and engineering of natural products from Lysobacter. Nat Prod Rep 2022; 39:842-874. [PMID: 35067688 DOI: 10.1039/d1np00063b] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Covering: up to August 2021Lysobacter is a genus of Gram-negative bacteria that was classified in 1987. Several Lysobacter species are emerging as new biocontrol agents for crop protection in agriculture. Lysobacter are prolific producers of new bioactive natural products that are largely underexplored. So far, several classes of structurally interesting and biologically active natural products have been isolated from Lysobacter. This article reviews the progress in Lysobacter natural product research over the past ten years, including molecular mechanisms for biosynthesis, regulation and mode of action, genome mining of cryptic biosynthetic gene clusters, and metabolic engineering using synthetic biology tools.
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Affiliation(s)
- Huan Yue
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
| | - Amanda Lynn Miller
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
| | - Vimmy Khetrapal
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
| | - Vishakha Jayaseker
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
| | - Stephen Wright
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
| | - Liangcheng Du
- Department of Chemistry, University of Nebraska-Lincoln, Lincoln, NE 68588-0304, USA.
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6
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Liu J, Zhao Y, Fu ZQ, Liu F. Monooxygenase LaPhzX is Involved in Self-Resistance Mechanisms during the Biosynthesis of N-Oxide Phenazine Myxin. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2021; 69:13524-13532. [PMID: 34735148 DOI: 10.1021/acs.jafc.1c05206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Self-resistance genes are deployed by many microbial producers of bioactive natural products to avoid self-toxicity. Myxin, a di-N-oxide phenazine produced by Lysobacter antibioticus OH13, is toxic to many microorganisms and tumor cells. Here, we uncovered a self-defense strategy featuring the antibiotic biosynthesis monooxygenase (ABM) family protein LaPhzX for myxin degradation. The gene LaPhzX is located in the myxin biosynthetic gene cluster (LaPhz), and its deletion resulted in bacterial mutants that are more sensitive to myxin. In addition, the LaPhzX mutants showed increased myxin accumulation and reduction of its derivative, compound 4, compared to the wild-type strain. Meanwhile, in vitro biochemical assays demonstrated that LaPhzX significantly degraded myxin in the presence of nicotinamide adenine dinucleotide phosphate (NADPH), nicotinamide adenine dinucleotide (NADH), flavin mononucleotide (FMN), and flavin adenine dinucleotide (FAD). In addition, heterologous expression of LaPhzX in Xanthomonas oryzae pv. oryzae and Escherichia coli increased their resistance to myxin. Overall, our work illustrates a monooxygenase-mediated self-resistance mechanism for phenazine antibiotic biosynthesis.
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Affiliation(s)
- Jiayu Liu
- College of Plant Protection (Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing 210095, China
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety─State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing 210014, China
| | - Yangyang Zhao
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety─State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing 210014, China
| | - Zheng Qing Fu
- Department of Biological Sciences, University of South Carolina, Columbia, South Carolina 29208, United States
| | - Fengquan Liu
- College of Plant Protection (Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing 210095, China
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety─State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing 210014, China
- College of Plant Protection/Key Laboratory of Green Prevention and Control of Tropical Plant Diseases and Pests, Ministry of Education, Hainan University, Haikou 570228, China
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Advances in Phenazines over the Past Decade: Review of Their Pharmacological Activities, Mechanisms of Action, Biosynthetic Pathways and Synthetic Strategies. Mar Drugs 2021; 19:md19110610. [PMID: 34822481 PMCID: PMC8620606 DOI: 10.3390/md19110610] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 10/21/2021] [Accepted: 10/22/2021] [Indexed: 01/25/2023] Open
Abstract
Phenazines are a large group of nitrogen-containing heterocycles, providing diverse chemical structures and various biological activities. Natural phenazines are mainly isolated from marine and terrestrial microorganisms. So far, more than 100 different natural compounds and over 6000 synthetic derivatives have been found and investigated. Many phenazines show great pharmacological activity in various fields, such as antimicrobial, antiparasitic, neuroprotective, insecticidal, anti-inflammatory and anticancer activity. Researchers continued to investigate these compounds and hope to develop them as medicines. Cimmino et al. published a significant review about anticancer activity of phenazines, containing articles from 2000 to 2011. Here, we mainly summarize articles from 2012 to 2021. According to sources of compounds, phenazines were categorized into natural phenazines and synthetic phenazine derivatives in this review. Their pharmacological activities, mechanisms of action, biosynthetic pathways and synthetic strategies were summarized. These may provide guidance for the investigation on phenazines in the future.
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8
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Viktorsson EÖ, Aesoy R, Støa S, Lekve V, Døskeland SO, Herfindal L, Rongved P. New prodrugs and analogs of the phenazine 5,10-dioxide natural products iodinin and myxin promote selective cytotoxicity towards human acute myeloid leukemia cells. RSC Med Chem 2021; 12:767-778. [PMID: 34124675 PMCID: PMC8152588 DOI: 10.1039/d1md00020a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2021] [Accepted: 03/29/2021] [Indexed: 12/22/2022] Open
Abstract
Novel chemotherapeutic strategies for acute myeloid leukemia (AML) treatment are called for. We have recently demonstrated that the phenazine 5,10-dioxide natural products iodinin (3) and myxin (4) exhibit potent and hypoxia-selective cell death on MOLM-13 human AML cells, and that the N-oxide functionalities are pivotal for the cytotoxic activity. Very few structure-activity relationship studies dedicated to phenazine 5,10-dioxides exist on mammalian cell lines and the present work describes our efforts regarding in vitro lead optimizations of the natural compounds iodinin (3) and myxin (4). Prodrug strategies reveal carbamate side chains to be the optimal phenol-attached group. Derivatives with no oxygen-based substituent (-OH or -OCH3) in the 6th position of the phenazine skeleton upheld potency if alkyl or carbamate side chains were attached to the phenol in position 1. 7,8-Dihalogenated- and 7,8-dimethylated analogs of 1-hydroxyphenazine 5,10-dioxide (21) displayed increased cytotoxic potency in MOLM-13 cells compared to all the other compounds studied. On the other hand, dihalogenated compounds displayed high toxicity towards the cardiomyoblast H9c2 cell line, while MOLM-13 selectivity of the 7,8-dimethylated analogs were less affected. Further, a parallel artificial membrane permeability assay (PAMPA) demonstrated the majority of the synthesized compounds to penetrate cell membranes efficiently, which corresponded to their cytotoxic potency. This work enhances the understanding of the structural characteristics essential for the activity of phenazine 5,10-dioxides, rendering them promising chemotherapeutic agents.
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Affiliation(s)
- Elvar Örn Viktorsson
- School of Pharmacy, Department of Pharmaceutical Chemistry, University of Oslo PO Box 1068 Blindern N0316 Oslo Norway
- School of Health Sciences, Faculty of Pharmaceutical Sciences, University of Iceland Hofsvallagata 53 IS-107 Reykjavik Iceland
| | - Reidun Aesoy
- Centre for Pharmacy, Department of Clinical Science, University of Bergen Jonas Lies vei 87 N-5021 Bergen Norway
| | - Sindre Støa
- School of Pharmacy, Department of Pharmaceutical Chemistry, University of Oslo PO Box 1068 Blindern N0316 Oslo Norway
| | - Viola Lekve
- Centre for Pharmacy, Department of Clinical Science, University of Bergen Jonas Lies vei 87 N-5021 Bergen Norway
| | - Stein Ove Døskeland
- Department of Biomedicine, University of Bergen Jonas Lies vei 91 N-5021 Bergen Norway
| | - Lars Herfindal
- Centre for Pharmacy, Department of Clinical Science, University of Bergen Jonas Lies vei 87 N-5021 Bergen Norway
| | - Pål Rongved
- School of Pharmacy, Department of Pharmaceutical Chemistry, University of Oslo PO Box 1068 Blindern N0316 Oslo Norway
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9
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McRose DL, Newman DK. Redox-active antibiotics enhance phosphorus bioavailability. Science 2021; 371:1033-1037. [PMID: 33674490 DOI: 10.1126/science.abd1515] [Citation(s) in RCA: 53] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Accepted: 01/13/2021] [Indexed: 12/13/2022]
Abstract
Microbial production of antibiotics is common, but our understanding of their roles in the environment is limited. In this study, we explore long-standing observations that microbes increase the production of redox-active antibiotics under phosphorus limitation. The availability of phosphorus, a nutrient required by all life on Earth and essential for agriculture, can be controlled by adsorption to and release from iron minerals by means of redox cycling. Using phenazine antibiotic production by pseudomonads as a case study, we show that phenazines are regulated by phosphorus, solubilize phosphorus through reductive dissolution of iron oxides in the lab and field, and increase phosphorus-limited microbial growth. Phenazines are just one of many examples of phosphorus-regulated antibiotics. Our work suggests a widespread but previously unappreciated role for redox-active antibiotics in phosphorus acquisition and cycling.
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Affiliation(s)
- Darcy L McRose
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA.,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
| | - Dianne K Newman
- Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, CA 91125, USA. .,Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA
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10
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Zhao Y, Liu J, Jiang T, Hou R, Xu G, Xu H, Liu F. Resistance-Nodulation-Division Efflux Pump, LexABC, Contributes to Self-Resistance of the Phenazine Di- N-Oxide Natural Product Myxin in Lysobacter antibioticus. Front Microbiol 2021; 12:618513. [PMID: 33679640 PMCID: PMC7927275 DOI: 10.3389/fmicb.2021.618513] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2020] [Accepted: 01/26/2021] [Indexed: 11/13/2022] Open
Abstract
Antibiotic-producing microorganisms have developed several self-resistance mechanisms to protect them from autotoxicity. Transporters belonging to the resistance- nodulation-division (RND) superfamily commonly confer multidrug resistance in Gram-negative bacteria. Phenazines are heterocyclic, nitrogen-containing and redox-active compounds that exhibit diverse activities. We previously identified six phenazines from Lysobacter antibioticus OH13, a soil bacterium emerging as a potential biocontrol agent. Among these phenazines, myxin, a di-N-oxide phenazine, exhibited potent activity against a variety of microorganisms. In this study, we identified a novel RND efflux pump gene cluster, designated lexABC, which is located far away in the genome from the myxin biosynthesis gene cluster. We found a putative LysR-type transcriptional regulator encoding gene lexR, which was adjacent to lexABC. Deletion of lexABC or lexR gene resulted in significant increasing susceptibility of strains to myxin and loss of myxin production. The results demonstrated that LexABC pump conferred resistance against myxin. The myxin produced at lower concentrations in these mutants was derivatized by deoxidation and O-methylation. Furthermore, we found that the abolishment of myxin with deletion of LaPhzB, which is an essential gene in myxin biosynthesis, resulted in significant downregulation of the lexABC. However, exogenous supplementation with myxin to LaPhzB mutant could efficiently induce the expression of lexABC genes. Moreover, lexR mutation also led to decreased expression of lexABC, which indicates that LexR potentially positively modulated the expression of lexABC. Our findings reveal a resistance mechanism against myxin of L. antibioticus, which coordinates regulatory pathways to protect itself from autotoxicity.
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Affiliation(s)
- Yangyang Zhao
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China
| | - Jiayu Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China.,College of Plant Protection (Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, China
| | - Tianping Jiang
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China
| | - Rongxian Hou
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China.,College of Plant Protection (Key Laboratory of Integrated Management of Crop Diseases and Pests), Nanjing Agricultural University, Nanjing, China
| | - Gaoge Xu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China
| | - Huiyong Xu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China
| | - Fengquan Liu
- Institute of Plant Protection, Jiangsu Academy of Agricultural Sciences, Jiangsu Key Laboratory for Food Quality and Safety-State Key Laboratory Cultivation Base of Ministry of Science and Technology, Nanjing, China.,Institute of Life Sciences, Jiangsu University, Zhenjiang, China
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11
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Nemeikaitė-Čėnienė A, Šarlauskas J, Misevičienė L, Marozienė A, Jonušienė V, Lesanavičius M, Čėnas N. Aerobic Cytotoxicity of Aromatic N-Oxides: The Role of NAD(P)H:Quinone Oxidoreductase (NQO1). Int J Mol Sci 2020; 21:ijms21228754. [PMID: 33228195 PMCID: PMC7699506 DOI: 10.3390/ijms21228754] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 11/13/2020] [Accepted: 11/18/2020] [Indexed: 12/24/2022] Open
Abstract
Derivatives of tirapazamine and other heteroaromatic N-oxides (ArN→O) exhibit tumoricidal, antibacterial, and antiprotozoal activities, which are typically attributed to bioreductive activation and free radical generation. In this work, we aimed to clarify the role of NAD(P)H:quinone oxidoreductase (NQO1) in ArN→O aerobic cytotoxicity. We synthesized 9 representatives of ArN→O with uncharacterized redox properties and examined their single-electron reduction by rat NADPH:cytochrome P-450 reductase (P-450R) and Plasmodium falciparum ferredoxin:NADP+ oxidoreductase (PfFNR), and by rat NQO1. NQO1 catalyzed both redox cycling and the formation of stable reduction products of ArN→O. The reactivity of ArN→O in NQO1-catalyzed reactions did not correlate with the geometric average of their activity towards P-450R- and PfFNR, which was taken for the parameter of their redox cycling efficacy. The cytotoxicity of compounds in murine hepatoma MH22a cells was decreased by antioxidants and the inhibitor of NQO1, dicoumarol. The multiparameter regression analysis of the data of this and a previous study (DOI: 10.3390/ijms20184602) shows that the cytotoxicity of ArN→O (n = 18) in MH22a and human colon carcinoma HCT-116 cells increases with the geometric average of their reactivity towards P-450R and PfFNR, and with their reactivity towards NQO1. These data demonstrate that NQO1 is a potentially important target of action of heteroaromatic N-oxides.
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Affiliation(s)
- Aušra Nemeikaitė-Čėnienė
- State Research Institute Center for Innovative Medicine, Santariškių St. 5, LT-08406 Vilnius, Lithuania;
| | - Jonas Šarlauskas
- Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania; (J.Š.); (L.M.); (A.M.); (M.L.)
| | - Lina Misevičienė
- Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania; (J.Š.); (L.M.); (A.M.); (M.L.)
| | - Audronė Marozienė
- Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania; (J.Š.); (L.M.); (A.M.); (M.L.)
| | - Violeta Jonušienė
- Institute of Biosciences of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania;
| | - Mindaugas Lesanavičius
- Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania; (J.Š.); (L.M.); (A.M.); (M.L.)
| | - Narimantas Čėnas
- Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania; (J.Š.); (L.M.); (A.M.); (M.L.)
- Correspondence: ; Tel.: +370-5-223-4392
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12
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Dar D, Thomashow LS, Weller DM, Newman DK. Global landscape of phenazine biosynthesis and biodegradation reveals species-specific colonization patterns in agricultural soils and crop microbiomes. eLife 2020; 9:59726. [PMID: 32930660 PMCID: PMC7591250 DOI: 10.7554/elife.59726] [Citation(s) in RCA: 30] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2020] [Accepted: 09/02/2020] [Indexed: 01/08/2023] Open
Abstract
Phenazines are natural bacterial antibiotics that can protect crops from disease. However, for most crops it is unknown which producers and specific phenazines are ecologically relevant, and whether phenazine biodegradation can counter their effects. To better understand their ecology, we developed and environmentally-validated a quantitative metagenomic approach to mine for phenazine biosynthesis and biodegradation genes, applying it to >800 soil and plant-associated shotgun-metagenomes. We discover novel producer-crop associations and demonstrate that phenazine biosynthesis is prevalent across habitats and preferentially enriched in rhizospheres, whereas biodegrading bacteria are rare. We validate an association between maize and Dyella japonica, a putative producer abundant in crop microbiomes. D. japonica upregulates phenazine biosynthesis during phosphate limitation and robustly colonizes maize seedling roots. This work provides a global picture of phenazines in natural environments and highlights plant-microbe associations of agricultural potential. Our metagenomic approach may be extended to other metabolites and functional traits in diverse ecosystems.
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Affiliation(s)
- Daniel Dar
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, United States.,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
| | - Linda S Thomashow
- Wheat Health, Genetics and Quality Research Unit, USDA Agricultural Research Service, Pullman, United States
| | - David M Weller
- Wheat Health, Genetics and Quality Research Unit, USDA Agricultural Research Service, Pullman, United States
| | - Dianne K Newman
- Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, United States.,Division of Biology and Biological Engineering, California Institute of Technology, Pasadena, United States
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13
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Mikhal’chenko LV, Nasybullina DV, Leonova MY, Syroeshkin MA, Gul’tyai VP. Electroreduction of Derivatives of N,N'-Dioxides of Phenazine and Quinoxaline in Nonaqueous Media and in the Presence of Proton Donors of Medium Strength. RUSS J ELECTROCHEM+ 2020. [DOI: 10.1134/s1023193520040102] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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14
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Zhang J, Wei L, Yang J, Ahmed W, Wang Y, Fu L, Ji G. Probiotic Consortia: Reshaping the Rhizospheric Microbiome and Its Role in Suppressing Root-Rot Disease of Panax notoginseng. Front Microbiol 2020; 11:701. [PMID: 32425904 PMCID: PMC7203884 DOI: 10.3389/fmicb.2020.00701] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Accepted: 03/25/2020] [Indexed: 12/13/2022] Open
Abstract
Root-rot disease caused by Fusarium oxysporum is a growing problem in agriculture for commercial cultivation of Panax notoginseng. Diverse microbes colonize plant roots, and numerous earlier studies have characterized the rhizospheric microbiome of P. notoginseng; nevertheless, the function of probiotic consortia on the rhizospheric microbiome against the root-rot disease remain elusive. We have compared and described the rhizospheric microbiome of lightly and severely diseased P. notoginseng as well as the interactions of the probiotic consortia and rhizospheric microbiome, and their function to alleviate the plant diseases were explored by inoculating probiotic consortia in bulk soil. From the perspective of microbial diversity, the rhizospheric dominant bacterial and fungal genera were utterly different between lightly and severely diseased plants. Through inoculating assembled probiotic consortia to diseased plant roots, we found that the application of probiotic consortia reshaped the rhizosphere microbiome, increasing the relative abundance of bacteria and fungi, while the relative abundance of potential pathogens was decreased significantly. We developed a microcosm system that provides a preliminary ecological framework for constructing an active probiotic community to reshape soil microbiota and restrain the disease. Microbial community structure differs between lightly and seriously diseased plants. The application of probiotic consortia changes the imbalance of micro-ecology to a state of relative health, reducing plant mortality. Plant disease suppression may be achieved by seeking and applying antagonistic microbes based on their direct inhibitory capability or by restructuring the soil microbiome structure and function.
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Affiliation(s)
- Jinhao Zhang
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
| | - Lanfang Wei
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
| | - Jun Yang
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
| | - Waqar Ahmed
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
| | - Yating Wang
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
| | - Lina Fu
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China.,Agriculture and Rural Affairs Committee of Fengdu County, Chongqing, China
| | - Guanghai Ji
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
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15
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Guo S, Liu R, Wang W, Hu H, Li Z, Zhang X. Designing an Artificial Pathway for the Biosynthesis of a Novel Phenazine N-Oxide in Pseudomonas chlororaphis HT66. ACS Synth Biol 2020; 9:883-892. [PMID: 32197042 DOI: 10.1021/acssynbio.9b00515] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Aromatic N-oxides are valuable due to their versatile chemical, pharmaceutical, and agricultural applications. Natural phenazine N-oxides possess potent biological activities and can be applied in many ways; however, few N-oxides have been identified. Herein, we developed a microbial system to synthesize phenazine N-oxides via an artificial pathway. First, the N-monooxygenase NaphzNO1 was predicted and screened in Nocardiopsis sp. 13-12-13 through a product comparison and gene sequencing. Subsequently, according to similarities in the chemical structures of substrates, an artificial pathway for the synthesis of a phenazine N-oxide in Pseudomonas chlororaphis HT66 was designed and established using three heterologous enzymes, a monooxygenase (PhzS) from P. aeruginosa PAO1, a monooxygenase (PhzO) from P. chlororaphis GP72, and the N-monooxygenase NaphzNO1. A novel phenazine derivative, 1-hydroxyphenazine N'10-oxide, was obtained in an engineered strain, P. chlororaphis HT66-SN. The phenazine N-monooxygenase NaphzNO1 was identified by metabolically engineering the phenazine-producing platform P. chlororaphis HT66. Moreover, the function of NaphzNO1, which can catalyze the conversion of 1-hydroxyphenazine but not that of 2-hydroxyphenazine, was confirmed in vitro. Additionally, 1-hydroxyphenazine N'10-oxide demonstrated substantial cytotoxic activity against two human cancer cell lines, MCF-7 and HT-29. Furthermore, the highest microbial production of 1-hydroxyphenazine N'10-oxide to date was achieved at 143.4 mg/L in the metabolically engineered strain P3-SN. These findings demonstrate that P. chlororaphis HT66 has the potential to be engineered as a platform for phenazine-modifying gene identification and derivative production. The present study also provides a promising alternative for the sustainable synthesis of aromatic N-oxides with unique chemical structures by N-monooxygenase.
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Affiliation(s)
- Shuqi Guo
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Rongfeng Liu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Wei Wang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Hongbo Hu
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
- National Experimental Teaching Center for Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhiyong Li
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Xuehong Zhang
- State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai 200240, China
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16
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Zhang J, Wei L, Yang J, Ahmed W, Wang Y, Fu L, Ji G. Probiotic Consortia: Reshaping the Rhizospheric Microbiome and Its Role in Suppressing Root-Rot Disease of Panax notoginseng. Front Microbiol 2020. [PMID: 32425904 DOI: 10.3389/fpls.2017.0701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/14/2023] Open
Abstract
Root-rot disease caused by Fusarium oxysporum is a growing problem in agriculture for commercial cultivation of Panax notoginseng. Diverse microbes colonize plant roots, and numerous earlier studies have characterized the rhizospheric microbiome of P. notoginseng; nevertheless, the function of probiotic consortia on the rhizospheric microbiome against the root-rot disease remain elusive. We have compared and described the rhizospheric microbiome of lightly and severely diseased P. notoginseng as well as the interactions of the probiotic consortia and rhizospheric microbiome, and their function to alleviate the plant diseases were explored by inoculating probiotic consortia in bulk soil. From the perspective of microbial diversity, the rhizospheric dominant bacterial and fungal genera were utterly different between lightly and severely diseased plants. Through inoculating assembled probiotic consortia to diseased plant roots, we found that the application of probiotic consortia reshaped the rhizosphere microbiome, increasing the relative abundance of bacteria and fungi, while the relative abundance of potential pathogens was decreased significantly. We developed a microcosm system that provides a preliminary ecological framework for constructing an active probiotic community to reshape soil microbiota and restrain the disease. Microbial community structure differs between lightly and seriously diseased plants. The application of probiotic consortia changes the imbalance of micro-ecology to a state of relative health, reducing plant mortality. Plant disease suppression may be achieved by seeking and applying antagonistic microbes based on their direct inhibitory capability or by restructuring the soil microbiome structure and function.
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Affiliation(s)
- Jinhao Zhang
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
| | - Lanfang Wei
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
| | - Jun Yang
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
| | - Waqar Ahmed
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
| | - Yating Wang
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
| | - Lina Fu
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
- Agriculture and Rural Affairs Committee of Fengdu County, Chongqing, China
| | - Guanghai Ji
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, China
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17
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Lina F, Ting W, Lanfang W, Jun Y, Qi L, Yating W, Xing W, Guanghai J. Specific detection of Lysobacter antibioticus strains in agricultural soil using PCR and real-time PCR. FEMS Microbiol Lett 2019; 365:5094558. [PMID: 30202922 DOI: 10.1093/femsle/fny219] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2018] [Accepted: 09/07/2018] [Indexed: 11/13/2022] Open
Abstract
Lysobacter antibioticus is an important biocontrol bacteria against phytopathogens in soil, and with the ability to produce nonvolatile antimicrobial metabolites has been extensively characterised. It is important to establish applicable techniques to detect and monitor L. antibioticus directly and accurately in soil samples. We developed and tested 13 primer sets according to phenazine gene (phzA, phzB, phzD, phzF, phzS) and the cyclohexanone monooxygenase gene (phzNO1); a pair of primer phzNO1 F1/phzNO1 R1 based on the cyclohexanone monooxygenase (phzNO1) gene of L. antibioticus strain OH13 was selected and optimized polymerase chain reaction (PCR) amplification conditions for rapid and accurate detection. After screening eight strains of L. antibioticus, two strains of Lysobacter enzymogenes, one strain of Lysobacter capsici, Arthrobacterium, Bacillus, Microbacterium, Burkholderia, Pseudomonas and other bacterial strains isolated from different agricultural soils, the phzNO1 F1/phzNO1 R1 primers amplified a single PCR band of about 229 bp from L. antibioticus. The detection sensitivity with primers phzNO1 F1/phzNO1 R1 was 5.14 × 104 fg/25μL of genomic DNA and 2.254 × 1010 to 2.254 × 1011 colony-forming units/mL for the soil samples. Quantitative PCR assays were to develope as a specific method to monitor the L. antibioticus population in soil as well as guide soil micro-ecological management.
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Affiliation(s)
- Fu Lina
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management under the Ministry of Education, Yunnan Agricultural University, Kunming 650201, P. R. China
| | - Wang Ting
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management under the Ministry of Education, Yunnan Agricultural University, Kunming 650201, P. R. China
| | - Wei Lanfang
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management under the Ministry of Education, Yunnan Agricultural University, Kunming 650201, P. R. China
| | - Yang Jun
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management under the Ministry of Education, Yunnan Agricultural University, Kunming 650201, P. R. China
| | - Liu Qi
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management under the Ministry of Education, Yunnan Agricultural University, Kunming 650201, P. R. China
| | - Wang Yating
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management under the Ministry of Education, Yunnan Agricultural University, Kunming 650201, P. R. China
| | - Wang Xing
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management under the Ministry of Education, Yunnan Agricultural University, Kunming 650201, P. R. China
| | - Ji Guanghai
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management under the Ministry of Education, Yunnan Agricultural University, Kunming 650201, P. R. China
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18
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Nemeikaitė-Čėnienė A, Šarlauskas J, Jonušienė V, Marozienė A, Misevičienė L, Yantsevich AV, Čėnas N. Kinetics of Flavoenzyme-Catalyzed Reduction of Tirapazamine Derivatives: Implications for Their Prooxidant Cytotoxicity. Int J Mol Sci 2019; 20:ijms20184602. [PMID: 31533349 PMCID: PMC6769651 DOI: 10.3390/ijms20184602] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2019] [Revised: 09/06/2019] [Accepted: 09/11/2019] [Indexed: 12/23/2022] Open
Abstract
Derivatives of tirapazamine and other heteroaromatic N-oxides (ArN→O) exhibit promising antibacterial, antiprotozoal, and tumoricidal activities. Their action is typically attributed to bioreductive activation and free radical generation. In this work, we aimed to clarify the mechanism(s) of aerobic mammalian cell cytotoxicity of ArN→O performing the parallel studies of their reactions with NADPH:cytochrome P-450 reductase (P-450R), adrenodoxin reductase/adrenodoxin (ADR/ADX), and NAD(P)H:quinone oxidoreductase (NQO1); we found that in P-450R and ADR/ADX-catalyzed single-electron reduction, the reactivity of ArN→O (n = 9) increased with their single-electron reduction midpoint potential (E17), and correlated with the reactivity of quinones. NQO1 reduced ArN→O at low rates with concomitant superoxide production. The cytotoxicity of ArN→O in murine hepatoma MH22a and human colon adenocarcinoma HCT-116 cells increased with their E17, being systematically higher than that of quinones. The cytotoxicity of both groups of compounds was prooxidant. Inhibitor of NQO1, dicoumarol, and inhibitors of cytochromes P-450 α-naphthoflavone, isoniazid and miconazole statistically significantly (p < 0.02) decreased the toxicity of ArN→O, and potentiated the cytotoxicity of quinones. One may conclude that in spite of similar enzymatic redox cycling rates, the cytotoxicity of ArN→O is higher than that of quinones. This is partly attributed to ArN→O activation by NQO1 and cytochromes P-450. A possible additional factor in the aerobic cytotoxicity of ArN→O is their reductive activation in oxygen-poor cell compartments, leading to the formation of DNA-damaging species similar to those forming under hypoxia.
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Affiliation(s)
- Aušra Nemeikaitė-Čėnienė
- State Research Institute Center for Innovative Medicine, Santariškių St. 5, LT-08406 Vilnius, Lithuania.
| | - Jonas Šarlauskas
- Department of Xenobiotics Biochemistry, Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania.
| | - Violeta Jonušienė
- Department of Biochemistry and Molecular Biology, Institute of Biosciences of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania.
| | - Audronė Marozienė
- Department of Xenobiotics Biochemistry, Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania.
| | - Lina Misevičienė
- Department of Xenobiotics Biochemistry, Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania.
| | - Aliaksei V Yantsevich
- Institute of Bioorganic Chemistry, NAS of Belarus, Kuprevicha 5/2, BY-220072 Minsk, Belarus.
| | - Narimantas Čėnas
- Department of Xenobiotics Biochemistry, Institute of Biochemistry of Vilnius University, Saulėtekio 7, LT-10257 Vilnius, Lithuania.
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19
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Li D, Wu P, Sun N, Lu YJ, Wong WL, Fang Z, Zhang K. The Diversity of Heterocyclic N-oxide Molecules: Highlights on their Potential in Organic Synthesis, Catalysis and Drug Applications. CURR ORG CHEM 2019. [DOI: 10.2174/1385272823666190408095257] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The synthesis and chemistry of heterocyclic N-oxide derivatives such as those from pyridine and indazole are very well-known due to their usefulness as versatile synthetic intermediates and their biological importance. These classes of organic compounds have been demonstrated in many interesting and amazing functionalities, particularly vital in the areas including metal complexes formation, catalysts design, asymmetric catalysis and synthesis, and medicinal applications (some potent N-oxide compounds with anticancer, antibacterial, anti-inflammatory activity, etc.). Therefore, the heterocyclic N-oxide motif has been successfully employed in a number of recent advanced chemistry and drug development investigations. In the present review, our primary aim was to provide a relevant summary focusing on the topics of organic synthesis and medical application potential of the compounds cited, which could be attractive and give some insights to researchers in the field. Therefore, we mainly highlight the importance of heterocyclic N-oxide derivatives including those synthesized from imidazole, indazole, indole, pyridazine, pyrazine, pyridine, and pyrimidine in organic syntheses and catalysis, and drug applications. Over the past years, a number of reviews have been published on the organic synthesis and catalysis of N-oxides. We thus concentrated on highlighting those rarely mentioned or recently reported systems.
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Affiliation(s)
- Dongli Li
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, P.R, China
| | - Panpan Wu
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, P.R, China
| | - Ning Sun
- Institute of Natural Medicine and Green Chemistry, School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, P. R, China
| | - Yu-Jing Lu
- Institute of Natural Medicine and Green Chemistry, School of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510006, P. R, China
| | - Wing-Leung Wong
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, P.R, China
| | - Zhiyuang Fang
- The Fifth Affiliated Hospital of Guangzhou Medical University, Guangzhou 510700, P.R., China
| | - Kun Zhang
- School of Biotechnology and Health Sciences, Wuyi University, Jiangmen 529020, P.R, China
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20
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Shen X, Gates KS. Enzyme-Activated Generation of Reactive Oxygen Species from Heterocyclic N-Oxides under Aerobic and Anaerobic Conditions and Its Relevance to Hypoxia-Selective Prodrugs. Chem Res Toxicol 2019; 32:348-361. [PMID: 30817135 DOI: 10.1021/acs.chemrestox.9b00036] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Enzymatic one-electron reduction of heterocyclic N-oxides can lead to the intracellular generation of reactive oxygen species via several different chemical pathways. These reactions may be relevant to hypoxia-selective anticancer drugs, antimicrobial agents, and unwanted toxicity of heterocylic nitrogen compounds.
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21
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Amberg A, Anger LT, Bercu J, Bower D, Cross KP, Custer L, Harvey JS, Hasselgren C, Honma M, Johnson C, Jolly R, Kenyon MO, Kruhlak NL, Leavitt P, Quigley DP, Miller S, Snodin D, Stavitskaya L, Teasdale A, Trejo-Martin A, White AT, Wichard J, Myatt GJ. Extending (Q)SARs to incorporate proprietary knowledge for regulatory purposes: is aromatic N-oxide a structural alert for predicting DNA-reactive mutagenicity? Mutagenesis 2019; 34:67-82. [PMID: 30189015 DOI: 10.1093/mutage/gey020] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2018] [Revised: 07/02/2018] [Accepted: 07/28/2018] [Indexed: 11/13/2022] Open
Abstract
(Quantitative) structure-activity relationship or (Q)SAR predictions of DNA-reactive mutagenicity are important to support both the design of new chemicals and the assessment of impurities, degradants, metabolites, extractables and leachables, as well as existing chemicals. Aromatic N-oxides represent a class of compounds that are often considered alerting for mutagenicity yet the scientific rationale of this structural alert is not clear and has been questioned. Because aromatic N-oxide-containing compounds may be encountered as impurities, degradants and metabolites, it is important to accurately predict mutagenicity of this chemical class. This article analysed a series of publicly available aromatic N-oxide data in search of supporting information. The article also used a previously developed structure-activity relationship (SAR) fingerprint methodology where a series of aromatic N-oxide substructures was generated and matched against public and proprietary databases, including pharmaceutical data. An assessment of the number of mutagenic and non-mutagenic compounds matching each substructure across all sources was used to understand whether the general class or any specific subclasses appear to lead to mutagenicity. This analysis resulted in a downgrade of the general aromatic N-oxide alert. However, it was determined there were enough public and proprietary data to assign the quindioxin and related chemicals as well as benzo[c][1,2,5]oxadiazole 1-oxide subclasses as alerts. The overall results of this analysis were incorporated into Leadscope's expert-rule-based model to enhance its predictive accuracy.
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Affiliation(s)
- Alexander Amberg
- Sanofi, R&D Preclinical Safety Frankfurt, Industriepark Höchst, Frankfurt am Main, Germany
| | - Lennart T Anger
- Sanofi, R&D Preclinical Safety Frankfurt, Industriepark Höchst, Frankfurt am Main, Germany
| | - Joel Bercu
- Gilead Sciences, Nonclinical Safety and Pathobiology, Foster City, CA, USA
| | | | | | - Laura Custer
- Bristol-Myers Squibb, Drug Safety Evaluation, New Brunswick, NJ, USA
| | - James S Harvey
- GlaxoSmithKline Pre-Clinical Development, Ware, Hertfordshire, UK
| | | | - Masamitsu Honma
- National Institute of Health Sciences, Division of Genetics & Mutagenesis, Kamiyoga, Setagaya-ku, Tokyo, Japan
| | | | - Robert Jolly
- Toxicology Division, Eli Lilly and Company, Indianapolis, IN, USA
| | - Michelle O Kenyon
- Pfizer Worldwide Research and Development, Drug Safety, Genetic Toxicology, Groton, CT, USA
| | - Naomi L Kruhlak
- U.S. Food and Drug Administration, Center for Drug Evaluation and Research, Silver Spring, MD, USA
| | - Penny Leavitt
- Bristol-Myers Squibb, Drug Safety Evaluation, New Brunswick, NJ, USA
| | | | | | | | - Lidiya Stavitskaya
- U.S. Food and Drug Administration, Center for Drug Evaluation and Research, Silver Spring, MD, USA
| | - Andrew Teasdale
- AstraZeneca, Pharmaceutical Technology and Development, Macclesfield, Cheshire, UK
| | | | - Angela T White
- GlaxoSmithKline Pre-Clinical Development, Ware, Hertfordshire, UK
| | - Joerg Wichard
- Bayer AG, Pharmaceuticals Division, Investigational Toxicology, Muellerstr, Berlin, Germany
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22
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Zeng Y, Ma J, Zhan Y, Xu X, Zeng Q, Liang J, Chen X. Hypoxia-activated prodrugs and redox-responsive nanocarriers. Int J Nanomedicine 2018; 13:6551-6574. [PMID: 30425475 PMCID: PMC6202002 DOI: 10.2147/ijn.s173431] [Citation(s) in RCA: 46] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Hypoxia is one of the marked features of malignant tumors, which is associated with several adaptation changes in the microenvironment of tumor cells. Therefore, targeting tumor hypoxia is a research hotspot for cancer therapy. In this review, we summarize the developing chemotherapeutic drugs for targeting hypoxia, including quinones, nitroaromatic/nitroimidazole, N-oxides, and transition metal complexes. In addition, redox-responsive bonds, such as nitroimidazole groups, azogroups, and disulfide bonds, are frequently used in drug delivery systems for targeting the redox environment of tumors. Both hypoxia-activated prodrugs and redox-responsive drug delivery nanocarriers have significant effects on targeting tumor hypoxia for cancer therapy. Hypoxia-activated prodrugs are commonly used in clinical trials with favorable prospects, while redox-responsive nanocarriers are currently at the experimental stage.
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Affiliation(s)
- Yun Zeng
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, Shaanxi Province, People's Republic of China, ,
| | - Jingwen Ma
- Department of Pharmaceutical Analysis, China Pharmaceutical University, Nanjing 210009, Jiangsu Province, People's Republic of China
| | - Yonghua Zhan
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, Shaanxi Province, People's Republic of China, ,
| | - Xinyi Xu
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, Shaanxi Province, People's Republic of China, ,
| | - Qi Zeng
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, Shaanxi Province, People's Republic of China, ,
| | - Jimin Liang
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, Shaanxi Province, People's Republic of China, ,
| | - Xueli Chen
- Engineering Research Center of Molecular and Neuro Imaging of the Ministry of Education, School of Life Science and Technology, Xidian University, Xi'an 710071, Shaanxi Province, People's Republic of China, ,
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23
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Fu L, Li H, Wei L, Yang J, Liu Q, Wang Y, Wang X, Ji G. Antifungal and Biocontrol Evaluation of Four Lysobacter Strains Against Clubroot Disease. Indian J Microbiol 2018; 58:353-359. [PMID: 30013280 DOI: 10.1007/s12088-018-0716-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2017] [Accepted: 03/06/2018] [Indexed: 10/17/2022] Open
Abstract
The effect of crude extract (Ce), seed coating agent (SCA) and whole bacterial broth culture (WBC) of Lysobacter strains was evaluated against the causal agent of clubroot formation in Cruciferous vegetables. The ability of four Lysobacter strains (L. antibioticus 6-B-1, L. antibioticus 6-T-4, L. antibioticus 13-B-1 and L. capsici ZST1-2) inhibited Plasmodiophora brassicae of resting spores and disease. Application of WBC of four Lysobacter strains inhibited clubroot disease, indicating that the disease suppression was due to antifungal compounds produced by the biocontrol bacterium in the culture. Development of clubroot on Chinese cabbage was inhibited when the WBC and SCA were applied before P. brassicae inoculation. Crude extract (Ce) of culture filtrate was effective in arresting the germination of resting spores of P. brassicae on slides. However, Lysobacter strains differed in their biocontrol effects, the strain L. capsci ZST1-2 recorded a high level of disease limiting effect.
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Affiliation(s)
- Lina Fu
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, 650201 People's Republic of China
| | - Hanmei Li
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, 650201 People's Republic of China
| | - Lanfang Wei
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, 650201 People's Republic of China
| | - Jun Yang
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, 650201 People's Republic of China
| | - Qi Liu
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, 650201 People's Republic of China
| | - Yating Wang
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, 650201 People's Republic of China
| | - Xing Wang
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, 650201 People's Republic of China
| | - Guanghai Ji
- Key Laboratory of Agriculture Biodiversity for Plant Disease Management Under the Ministry of Education, Yunnan Agricultural University, Kunming, 650201 People's Republic of China
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Dumpala RMR, Rawat N, Boda A, Ali SM, Tomar B. Complexation of thorium with pyridine monocarboxylate-N-oxides: Thermodynamic and computational studies. THE JOURNAL OF CHEMICAL THERMODYNAMICS 2018; 122:13-22. [PMID: 32226127 PMCID: PMC7094258 DOI: 10.1016/j.jct.2018.02.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/25/2017] [Revised: 01/19/2018] [Accepted: 02/05/2018] [Indexed: 06/10/2023]
Abstract
The feed wastes and waste water treatment plants are the major sources for the entry of N-oxides into the soils then to aquatic life. The complexation of actinides with potentially stable anthropogenic ligands facilitate the transportation and migration of the actinides from the source confinement. The present study describes the determination of thermodynamic parameters for the complexation of Th(IV) with the three isomeric pyridine monocarboxylates (PCNO) namely picolinic acid-N-oxide (PANO), nicotinic acid-N-oxide (NANO) and isonicotinic acid-N-oxide (IANO). The potentiometric and isothermal calorimetric titrations were carried out to determine the stability and enthalpy of the formations for all the Th(IV)-PCNO complexes. Th-PANO complexes are more stable than Th-NANO and Th-IANO complexes which can be attributed to chelate formation in the former complexes. Formation of all the Th-PCNO complexes are endothermic and are entropy driven. The geometries for all the predicted complexes are optimized the energies, bond distances and charges on individual atoms are obtained using TURBOMOLE software. The theoretical calculation corroborated the experimental determinations.
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Affiliation(s)
- Rama Mohana Rao Dumpala
- Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Neetika Rawat
- Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - Anil Boda
- Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - Sk. Musharaf Ali
- Chemical Engineering Division, Bhabha Atomic Research Centre, Mumbai 400085, India
| | - B.S. Tomar
- Radioanalytical Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
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Jiang J, Guiza Beltran D, Schacht A, Wright S, Zhang L, Du L. Functional and Structural Analysis of Phenazine O-Methyltransferase LaPhzM from Lysobacter antibioticus OH13 and One-Pot Enzymatic Synthesis of the Antibiotic Myxin. ACS Chem Biol 2018; 13:1003-1012. [PMID: 29510028 DOI: 10.1021/acschembio.8b00062] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Myxin is a well-known antibiotic that had been used for decades. It belongs to the phenazine natural products that exhibit various biological activities, which are often dictated by the decorating groups on the heteroaromatic three-ring system. The three rings of myxin carry a number of decorations, including an unusual aromatic N5, N10-dioxide. We previously showed that phenazine 1,6-dicarboxylic acid (PDC) is the direct precursor of myxin, and two redox enzymes (LaPhzS and LaPhzNO1) catalyze the decarboxylative hydroxylation and aromatic N-oxidations of PDC to produce iodinin (1.6-dihydroxy- N5, N10-dioxide phenazine). In this work, we identified the LaPhzM gene from Lysobacter antibioticus OH13 and demonstrated that LaPhzM encodes a SAM-dependent O-methyltransferase converting iodinin to myxin. The results further showed that LaPhzM is responsible for both monomethoxy and dimethoxy formation in all phenazine compounds isolated from strain OH13. LaPhzM exhibits relaxed substrate selectivity, catalyzing O-methylation of phenazines with non-, mono-, or di- N-oxide. In addition, we demonstrated a one-pot biosynthesis of myxin by in vitro reconstitution of the three phenazine-ring decorating enzymes. Finally, we determined the X-ray crystal structure of LaPhzM with a bound cofactor at 1.4 Å resolution. The structure provided molecular insights into the activity and selectivity of the first characterized phenazine O-methyltransferase. These results will facilitate future exploitation of the thousands of phenazines as new antibiotics through metabolic engineering and chemoenzymatic syntheses.
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Affiliation(s)
- Jiasong Jiang
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
| | | | | | - Stephen Wright
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
| | | | - Liangcheng Du
- Department of Chemistry, University of Nebraska—Lincoln, Lincoln, Nebraska 68588, United States
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Zhou H, Gao J, Chen Z, Duan S, Li C, Qiao R. Double-strand cleavage of DNA by a polyamide-phenazine-di-N-oxide conjugate. Bioorg Med Chem Lett 2017; 28:284-288. [PMID: 29292228 DOI: 10.1016/j.bmcl.2017.12.058] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Revised: 12/09/2017] [Accepted: 12/23/2017] [Indexed: 11/15/2022]
Abstract
Phenazine and its derivatives have been widely applied as nucleic acid cleavage agents due to active oxygen activating the C-H bond of the substrate. However, diffusion of oxygen radicals limits their potential applications in the DNA-targeted metal-free drug. Introduction of groove binder moiety such as polyamide enhanced the regional stability of radical molecules and reduced cytotoxicity of the drugs. In this work, we described the design and synthesis of a polyamide-modified phenazine-di-N-oxide as a DNA double-strand cleavage agent. The gel assays showed the hybrid conjugates can effectively break DNA double strands in a non-random manner under physiological conditions. The probable binding mode to DNA was investigated by sufficient spectral experiments, revealing weak interaction between hybrid ligand and nucleic acid molecules. The results of our study have implications on the design of groove-binding hybrid molecules as new artificial nucleases and may provide a strategy for developing efficient and safe DNA cleavage reagents.
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Affiliation(s)
- Hang Zhou
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China
| | - Juanhong Gao
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China
| | - Zhaohang Chen
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China
| | - Shan Duan
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China
| | - Chao Li
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China.
| | - Renzhong Qiao
- State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, PR China; State Key Laboratory of Natural and Biomimetic Drugs School of Pharmaceutical Sciences, Peking University Health Sciences Center, Beijing 100083, PR China.
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Wróbel Z, Plichta K, Kwast A. Reactivity and substituent effects in the cyclization of N -aryl-2-nitrosoanilines to phenazines. Tetrahedron 2017. [DOI: 10.1016/j.tet.2017.04.046] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Total synthesis and antileukemic evaluations of the phenazine 5,10-dioxide natural products iodinin, myxin and their derivatives. Bioorg Med Chem 2017; 25:2285-2293. [PMID: 28284865 DOI: 10.1016/j.bmc.2017.02.058] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2017] [Revised: 02/22/2017] [Accepted: 02/25/2017] [Indexed: 12/13/2022]
Abstract
A new efficient total synthesis of the phenazine 5,10-dioxide natural products iodinin and myxin and new compounds derived from them was achieved in few steps, a key-step being 1,6-dihydroxyphenazine di-N-oxidation. Analogues prepared from iodinin, including myxin and 2-ethoxy-2-oxoethoxy derivatives, had fully retained cytotoxic effect against human cancer cells (MOLM-13 leukemia) at atmospheric and low oxygen level. Moreover, iodinin was for the first time shown to be hypoxia selective. The structure-activity relationship for leukemia cell death induction revealed that the level of N-oxide functionality was essential for cytotoxicity. It also revealed that only one of the two phenolic functions is required for activity, allowing the other one to be modified without loss of potency.
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Odhiambo BO, Xu G, Qian G, Liu F. Evidence of an Unidentified Extracellular Heat-Stable Factor Produced by Lysobacter enzymogenes (OH11) that Degrade Fusarium graminearum PH1 Hyphae. Curr Microbiol 2017; 74:437-448. [PMID: 28213660 DOI: 10.1007/s00284-017-1206-1] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2016] [Accepted: 01/25/2017] [Indexed: 11/26/2022]
Abstract
Lysobacter enzymogenes OH11 produces heat-stable antifungal factor (HSAF) and lytic enzymes possessing antifungal activity. This study bio-prospected for other potential antifungal factors besides those above. The cells and extracellular metabolites of L. enzymogenes OH11 and the mutants ΔchiA, ΔchiB, ΔchiC, Δclp, Δpks, and ΔpilA were examined for antifungal activity against Fusarium graminearum PH1, the causal agent of Fusarium head blight (FHB). Results evidenced that OH11 produces an unidentified extracellular heat-stable degrading metabolite (HSDM) that exhibit degrading activity on F. graminearum PH1 chitinous hyphae. Interestingly, both heat-treated and non-heat-treated extracellular metabolites of OH11 mutants exhibited hyphae-degrading activity against F. graminearum PH1. Enzyme activity detection of heat-treated metabolites ruled out the possibility of enzyme degradation activity. Remarkably, the PKS-NRPS-deficient mutant Δpks cannot produce HSAF or analogues, yet its metabolites exhibited hyphae-degrading activity. HPLC analysis confirmed no HSAF production by Δpks. Δclp lacks hyphae-degrading ability. Therefore, clp regulates HSDM and extracellular lytic enzymes production in L. enzymogenes OH11. ΔpilA had impaired surface cell motility and significantly reduced antagonistic properties. ΔchiA, ΔchiB, and ΔchiC retained hyphae-degrading ability, despite having reduced abilities to produce chitinase enzymes. Ultimately, L. enzymogenes OH11 can produce other unidentified HSDM independent of the PKS-NRPS genes. This suggests HSAF and lytic enzymes production are a fraction of the antifungal mechanisms in OH11. Characterization of HSDM, determination of its biosynthetic gene cluster and understanding its mode of action will provide new leads in the search for effective drugs for FHB management.
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Affiliation(s)
| | - Gaoge Xu
- College of Plant Protection Nanjing Agricultural University, Nanjing, 210095, China
| | - Guoliang Qian
- College of Plant Protection Nanjing Agricultural University, Nanjing, 210095, China
| | - Fengquan Liu
- College of Plant Protection Nanjing Agricultural University, Nanjing, 210095, China
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Sinha S, Shen X, Gallazzi F, Li Q, Zmijewski JW, Lancaster JR, Gates KS. Generation of Reactive Oxygen Species Mediated by 1‑Hydroxyphenazine, a Virulence Factor of Pseudomonas aeruginosa. Chem Res Toxicol 2016; 28:175-81. [PMID: 25590513 DOI: 10.1021/tx500259s] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
1-Hydroxyphenazine (1-HP) is a virulence factor produced by Pseudomonas aeruginosa. In this study,supercoiled plasmid DNA was employed as an analytical tool for the detection of ROS generation mediated by 1-HP. These assays provided evidence that 1-HP, in conjunction with NADPH alone or NADPH and the enzyme NADPH:cytochrome P450 reductase, mediated the production of superoxide radical under physiological conditions. Experiments with murine macrophage RAW264.7 cells and profluorescent ROS probes dichlorodihydrofluorescein or dihydroethidine provided preliminary evidence that 1-HP mediates the generation of intracellular oxidants. Generation of reactive oxygen species may contribute to the virulence properties of 1-HP in P. aeruginosa infections.
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31
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Zhao Y, Qian G, Ye Y, Wright S, Chen H, Shen Y, Liu F, Du L. Heterocyclic Aromatic N-Oxidation in the Biosynthesis of Phenazine Antibiotics from Lysobacter antibioticus. Org Lett 2016; 18:2495-8. [PMID: 27145204 DOI: 10.1021/acs.orglett.6b01089] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
Heterocyclic aromatic N-oxides often have potent biological activities, but the mechanism for aromatic N-oxidation is unclear. Six phenazine antibiotics were isolated from Lysobacter antibioticus OH13. A 10 gene cluster was identified for phenazine biosynthesis. Mutation of LaPhzNO1 abolished all N-oxides, while non-oxides markedly increased. LaPhzNO1 is homologous to Baeyer-Villiger flavoproteins but was shown to catazlye phenazine N-oxidation. LaPhzNO1 and LaPhzS together converted phenazine 1,6-dicarboxylic acid to 1,6-dihydroxyphenazine N5,N10-dioxide. LaPhzNO1 also catalyzed N-oxidation of 8-hydroxyquinoline.
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Affiliation(s)
- Yangyang Zhao
- College of Plant Protection, Nanjing Agricultural University , Nanjing 210095, China.,Department of Chemistry, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States
| | - Guoliang Qian
- College of Plant Protection, Nanjing Agricultural University , Nanjing 210095, China
| | - Yonghao Ye
- College of Plant Protection, Nanjing Agricultural University , Nanjing 210095, China
| | - Stephen Wright
- Department of Chemistry, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States
| | - Haotong Chen
- Department of Chemistry, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States
| | - Yuemao Shen
- Key Laboratory of Chemical Biology, School of Pharmaceutical Sciences, Shandong University , Jinan 250100, China
| | - Fengquan Liu
- College of Plant Protection, Nanjing Agricultural University , Nanjing 210095, China.,Institute of Plant Protection, Jiangsu Academy of Agricultural Science , Nanjing 210014, China
| | - Liangcheng Du
- Department of Chemistry, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States
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On the reactivity of benzo[a]phenazine-5,6-dione 7-oxides with methanolic alkali and pyrrolidine. Chem Heterocycl Compd (N Y) 2015. [DOI: 10.1007/s10593-015-1676-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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Jezierska A. N-H⋯O versus O-H⋯O: density functional calculation and first principle molecular dynamics study on a quinoline-2-carboxamide N-oxide. J Mol Model 2015; 21:47. [PMID: 25690363 PMCID: PMC4333232 DOI: 10.1007/s00894-015-2587-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 01/19/2015] [Indexed: 11/26/2022]
Abstract
N-oxide-type compounds are the object of current research interest due to the presence of resonance-assisted N–H⋯O hydrogen bonds. Here, the metric and spectroscopic parameters of N-methyl-quinoline-2-carboxamide 1-oxide were computed on the basis of density functional theory and Car-Parrinello molecular dynamics. Computations were performed in vacuo and in solid state; for both phases additional simulations with Grimme’s dispersion correction were carried out. The approaches used were able to reproduce correctly the structural aspects of the studied compound and shed more light on the hydrogen bonding with special focus on bridge proton mobility. Proton transfer phenomena were found not to occur in the investigated compound, and the bridge proton was localized to the donor site. This observation is in agreement with the classical theory of the acidity of donor–acceptor sites. The presence of hydrogen bonding was confirmed using atoms-in-molecules theory. The computational results were compared with available experimental data.
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Affiliation(s)
- Aneta Jezierska
- Faculty of Chemistry, University of Wrocław, ul. F. Joliot-Curie 14, 50-383, Wrocław, Poland,
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Redox metabolites signal polymicrobial biofilm development via the NapA oxidative stress cascade in Aspergillus. Curr Biol 2014; 25:29-37. [PMID: 25532893 DOI: 10.1016/j.cub.2014.11.018] [Citation(s) in RCA: 59] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2014] [Revised: 10/15/2014] [Accepted: 11/06/2014] [Indexed: 01/19/2023]
Abstract
BACKGROUND Filamentous fungi and bacteria form mixed-species biofilms in nature and diverse clinical contexts. They secrete a wealth of redox-active small molecule secondary metabolites, which are traditionally viewed as toxins that inhibit growth of competing microbes. RESULTS Here, we report that these "toxins" can act as interspecies signals, affecting filamentous fungal development via oxidative stress regulation. Specifically, in coculture biofilms, Pseudomonas aeruginosa phenazine-derived metabolites differentially modulated Aspergillus fumigatus development, shifting from weak vegetative growth to induced asexual sporulation (conidiation) along a decreasing phenazine gradient. The A. fumigatus morphological shift correlated with the production of phenazine radicals and concomitant reactive oxygen species (ROS) production generated by phenazine redox cycling. Phenazine conidiation signaling was conserved in the genetic model A. nidulans and mediated by NapA, a homolog of AP-1-like bZIP transcription factor, which is essential for the response to oxidative stress in humans, yeast, and filamentous fungi. Expression profiling showed phenazine treatment induced a NapA-dependent response of the global oxidative stress metabolome, including the thioredoxin, glutathione, and NADPH-oxidase systems. Conidiation induction in A. nidulans by another microbial redox-active secondary metabolite, gliotoxin, also required NapA. CONCLUSIONS This work highlights that microbial redox metabolites are key signals for sporulation in filamentous fungi, which are communicated through an evolutionarily conserved eukaryotic stress response pathway. It provides a foundation for interspecies signaling in environmental and clinical biofilms involving bacteria and filamentous fungi.
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Ravichandran J, Gurumoorthy P, Imran Musthafa MA, Kalilur Rahiman A. Antioxidant, DNA binding and nuclease activities of heteroleptic copper(II) complexes derived from 2-((2-(piperazin-1-yl)ethylimino)methyl)-4-substituted phenols and diimines. SPECTROCHIMICA ACTA. PART A, MOLECULAR AND BIOMOLECULAR SPECTROSCOPY 2014; 133:785-793. [PMID: 24998685 DOI: 10.1016/j.saa.2014.06.045] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/15/2014] [Revised: 05/27/2014] [Accepted: 06/03/2014] [Indexed: 06/03/2023]
Abstract
A series of heteroleptic copper(II) complexes of the type [CuL(1-4)(diimine)](ClO4)2 (1-8) [L(1-4)=2-((2-(piperazin-1-yl)ethylimino)methyl)-4-substituted phenols, and diimine=2,2'-bipyridyl (bpy) or 1,10-phenanthroline (phen)], have been synthesized and characterized by spectroscopic methods. The IR spectra of complexes indicate the presence of uncoordinated perchlorate anions and the electronic spectra revealed the square pyramidal geometry with N4O coordination environment around copper(II) nuclei. Electrochemical studies of the mononuclear complexes evidenced one-electron irreversible reduction wave in the cathodic region. The EPR spectra of complexes with g|| (2.206-2.214) and A|| (154-172×10(-)(4)cm(-)(1)) values support the square-based CuN3O coordination chromophore and the presence of unpaired electron localized in [Formula: see text] ground state. Antioxidant studies against DPPH revealed effective radical scavenging properties of the synthesized complexes. Binding studies suggest that the heteroleptic copper(II) complexes interact with calf thymus DNA (CT-DNA) through minor-groove and electrostatic interaction, and all the complexes display pronounced nuclease activity against supercoiled pBR322 DNA.
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Affiliation(s)
- J Ravichandran
- Post-Graduate and Research Department of Chemistry, The New College (Autonomous), Chennai 600 014, India; Research and Development Department, Amrutanjan Healthcare Limited, Mylapore, Chennai 600 004, India
| | - P Gurumoorthy
- Post-Graduate and Research Department of Chemistry, The New College (Autonomous), Chennai 600 014, India
| | - M A Imran Musthafa
- Post-Graduate and Research Department of Chemistry, The New College (Autonomous), Chennai 600 014, India
| | - A Kalilur Rahiman
- Post-Graduate and Research Department of Chemistry, The New College (Autonomous), Chennai 600 014, India.
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Wróbel Z, Stachowska K, Kwast A. Phenazines and TheirN-Oxides as Products of Cyclization ofN-Aryl-2-nitrosoanilines - Disproof of the Reported Homolytic Cross-Coupling Process Leading to Benzo[c]cinnoline Oxides. European J Org Chem 2014. [DOI: 10.1002/ejoc.201402624] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
Covering: up to the end of 2013. Myxobacteria produce a vast range of structurally diverse natural products with prominent biological activities. Here, we provide a detailed description and judge the potential of all antibiotically active myxobacterial compounds as lead structures, pointing out their particularities and, if known, their mode of action. Thus, the review provides an overview of the potential of specific compounds, suitable for future investigations and possible clinical applications.
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Affiliation(s)
- Till F Schäberle
- Institute for Pharmaceutical Biology, University of Bonn, Nussallee 6, 53115 Bonn, Germany.
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Shen X, Rajapakse A, Gallazzi F, Junnotula V, Fuchs-Knotts T, Glaser R, Gates KS. Isotopic labeling experiments that elucidate the mechanism of DNA strand cleavage by the hypoxia-selective antitumor agent 1,2,4-benzotriazine 1,4-di-N-oxide. Chem Res Toxicol 2013; 27:111-8. [PMID: 24328261 DOI: 10.1021/tx400356y] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The 1,2,4-benzotriazine 1,4-dioxides are an important class of potential anticancer drugs that selectively kill the low-oxygen (hypoxic) cells found in solid tumors. These compounds undergo intracellular one-electron enzymatic reduction to yield an oxygen-sensitive drug radical intermediate that partitions forward, under hypoxic conditions, to generate a highly reactive secondary radical that causes cell killing DNA damage. Here, we characterized bioreductively activated, hypoxia-selective DNA-strand cleavage by 1,2,4-benzotriazine 1,4-dioxide. We found that one-electron enzymatic activation of 1,2,4-benzotriazine 1,4-dioxide under hypoxic conditions in the presence of the deuterium atom donor methanol-d4 produced nondeuterated mono-N-oxide metabolites. This and the results of other isotopic labeling studies provided evidence against the generation of atom-abstracting drug radical intermediates and are consistent with a DNA-damage mechanism involving the release of hydroxyl radical from enzymatically activated 1,2,4-benzotriazine 1,4-dioxides.
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Affiliation(s)
- Xiulong Shen
- Department of Chemistry, University of Missouri , 125 Chemistry Building, Columbia, Missouri 65211, United States
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Rajapakse A, Linder C, Morrison RD, Sarkar U, Leigh ND, Barnes CL, Daniels JS, Gates KS. Enzymatic conversion of 6-nitroquinoline to the fluorophore 6-aminoquinoline selectively under hypoxic conditions. Chem Res Toxicol 2013; 26:555-63. [PMID: 23488987 DOI: 10.1021/tx300483z] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
There is substantial interest in small molecules that can be used to detect or kill the hypoxic (low oxygen) cells found in solid tumors. Nitroaryl moieties are useful components in the design of hypoxia-selective imaging agents and prodrugs because one-electron reductases can convert the nitroaryl group to nitroso, hydroxylamino, and amino metabolites selectively under low oxygen conditions. Here, we describe the in vitro, cell free metabolism of a pro-fluorescent substrate, 6-nitroquinoline (1) under both aerobic and hypoxic conditions. Both LC-MS and fluorescence spectroscopic analyses provided evidence that the one-electron reducing enzyme system, xanthine/xanthine oxidase, converted the nonfluorescent parent compound 1 to the known fluorophore 6-aminoquinoline (2) selectively under hypoxic conditions. The presumed intermediate in this reduction process, 6-hydroxylaminoquinoline (6), is fluorescent and can be efficiently converted by xanthine/xanthine oxidase to 2 only under hypoxic conditions. This finding provides evidence for multiple oxygen-sensitive steps in the enzymatic conversion of nitroaryl compounds to the corresponding amino derivatives. In a side reaction that is separate from the bioreductive metabolism of 1, xanthine oxidase converted 1 to 6-nitroquinolin-2(1H)-one (5). These studies may enable the use of 1 as a fluorescent substrate for the detection and profiling of one-electron reductases in cell culture or biopsy samples. In addition, the compound may find use as a fluorogenic probe for the detection of hypoxia in tumor models. The occurrence of side products such as 5 in the enzymatic bioreduction of 1 underscores the importance of metabolite identification in the characterization of hypoxia-selective probes and drugs that employ nitroaryl units as oxygen sensors.
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Affiliation(s)
- Anuruddha Rajapakse
- Department of Chemistry, University of Missouri , 125 Chemistry Building, Columbia, Missouri 65211, United States
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Yang W, Fu J, Xiao X, Yan H, Bao W, Wang D, Hao L, Nussler AK, Yao P, Liu L. Quinocetone triggers oxidative stress and induces cytotoxicity and genotoxicity in human peripheral lymphocytes of both genders. JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE 2013; 93:1317-1325. [PMID: 23027643 DOI: 10.1002/jsfa.5891] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2012] [Revised: 06/02/2012] [Accepted: 08/28/2012] [Indexed: 06/01/2023]
Abstract
BACKGROUND Quinocetone has been widely used as an animal growth promoter in China. However, available data showed that QCT has potential genotoxicity. This study was conducted to investigate the cytotoxicity and genotoxicity of QCT in human lymphocytes. RESULTS CCK-8 assay demonstrated the severe inhibitory effects by QCT in a dose- and time-dependent manner. DNA damage analysis using alkalic Comet assay revealed a pronounced increase of DNA fragmentation in cells. In contrast, DNA damage was significantly decreased after incubation with S9 mix. This finding demonstrated that the intermediate metabolites of this drug exerted lower genotoxicity than its parent drugs. We further described chromosomal damage induced by this drug employing cytokinesis-block micronucleus assay. The micronucleus frequency was significantly increased in quinocetone groups as compared to controls. Similar to the observation in Comet assay, incorporation of S9 mix in the cytokinesis-block micronucleus assay could markedly alleviate the chromosomal damage. Moreover, QCT could invoke increase of reactive oxygen species generation in cells. Intriguingly, the toxicity of QCT was more prominent in samples from males than those from females under the same conditions. CONCLUSION QCT could induce potential cytotoxicity and genotoxicity in human lymphocytes.
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Affiliation(s)
- Wei Yang
- Hubei Key Laboratory of Food Nutrition and Safety, School of Public Health, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430030, China
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Abstract
The gliding Gram-negative Lysobacter bacteria are emerging as a promising source of new bioactive natural products. These ubiquitous freshwater and soil microorganisms are fast growing, simple to use and maintain, and genetically amenable for biosynthetic engineering. This Highlight reviews a group of biologically active and structurally distinct natural products from the genus Lysobacter, with a focus on their biosyntheses. Although Lysobacter sp. are known as prolific producers of bioactive natural products, detailed molecular mechanistic studies of their enzymatic assembly have been surprisingly scarce. We hope to provide a snapshot of the important work done on the lysobacterial natural products and to provide useful information for future biosynthetic engineering of novel antibiotics in Lysobacter.
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Affiliation(s)
- Yunxuan Xie
- Department of Chemistry, University of Nebraska-Lincoln, NE 68588, USA
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Liu L, Zhai Q, Hong T, Ge Y, Hu P, Weng X, Liu Y, Zhou X. Selective cleavage of DNA at guanosine bases which locate in DNA non-duplex portions within duplexes by ruthenium(II) complexes. Inorganica Chim Acta 2013. [DOI: 10.1016/j.ica.2012.08.021] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
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Yin J, Glaser R, Gates KS. On the reaction mechanism of tirapazamine reduction chemistry: unimolecular N-OH homolysis, stepwise dehydration, or triazene ring-opening. Chem Res Toxicol 2012; 25:634-45. [PMID: 22390168 DOI: 10.1021/tx200546u] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Abstract
The initial steps of the activation of tirapazamine (TPZ, 1, 3-amino-1,2,4-benzotriazine 1,4-N,N-dioxide) under hypoxic conditions consist of the one-electron reduction of 1 to radical anion 2 and the protonation of 2 at O(N4) or O(N1) to form neutral radicals 3 and 4, respectively. There are some questions, however, as to whether radicals 3 and/or 4 will then undergo N-OH homolyses 3 → 5 + ·OH and 4 → 6 + ·OH or, alternatively, whether 3 and/or 4 may react by dehydration and form aminyl radicals via 3 → 11 + H(2)O and 4 → 12 + H(2)O or phenyl radicals via 3 → 17 + H(2)O. These outcomes might depend on the chemistry after the homolysis of 3 and/or 4, that is, dehydration may be the result of a two-step sequence that involves N-OH homolysis and formation of ·OH aggregates of 5 and 6 followed by H-abstraction within the ·OH aggregates to form hydrates of aminyls 11 and 12 or of phenyl 17. We studied these processes with configuration interaction theory, perturbation theory, and density functional theory. All stationary structures of OH aggregates of 5 and 6, of H(2)O aggregates of 11, 12, and 17, and of the transition state structures for H-abstraction were located and characterized by vibrational analysis and with methods of electron and spin-density analysis. The doublet radical 17 is a normal spin-polarized radical, whereas the doublet radicals 11 and 12 feature quartet instabilities. The computed reaction energies and activation barriers allow for dehydration in principle, but the productivity of all of these channels should be low for kinetic and dynamic reasons. With a view to plausible scenarios for the generation of latent aryl radical species without dehydration, we scanned the potential energy surfaces of 2-4 as a function of the (O)N1-Y (Y = C5a, N2) and (O)N4-Z (Z = C4a, C3) bond lengths. The elongation of any one of these bonds by 0.5 Å requires less than 25 kcal/mol, and this finding strongly suggests the possibility of bimolecular reactions of the spin-trap molecules with 2-4 concomitant with triazene ring-opening.
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Affiliation(s)
- Jian Yin
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
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Yin J, Glaser R, Gates KS. Electron and spin-density analysis of tirapazamine reduction chemistry. Chem Res Toxicol 2012; 25:620-33. [PMID: 22390194 DOI: 10.1021/tx2005458] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
Tirapazamine (TPZ, 1, 3-amino-1,2,4-benzotriazine 1,4-N,N-dioxide), the radical anion 2 formed by one-electron reduction of 1, and neutral radicals 3 and 4 formed by protonation of 2 at O(N4) or O(N1), respectively, and their N-OH homolyses 3 → 5 + ·OH and 4 → 6 + ·OH have been studied with configuration interaction theory, perturbation theory, and density functional theory. A comprehensive comparative analysis is presented of structures and electronic structures and with focus on the development of an understanding of the spin-density distributions of the radical species. The skeletons of radicals 3 and 4 are distinctly nonplanar, several stereoisomeric structures are discussed, and there exists an intrinsic preference for 3 over 4. The N-oxides 1, 5, and 6 have closed-shell singlet ground states and low-lying, singlet biradical (SP-1, SP-6) or biradicaloid (SP-5) excited states. The doublet radicals 2, 3, and 4 are heavily spin-polarized. Most of the spin density of the doublet radicals 2, 3, and 4 is located in one (N,O)-region, and in particular, 3 and 4 are not C3-centered radicals. Significant amounts of spin density occur in both rings in the singlet biradical(oid) excited states of 1, 5, and 6. The dipole moment of the N2-C3(X) bond is large, and the nature of X provides a powerful handle to modulate the N2-C3 bond polarity with opposite effects on the two NO regions. Our studies show very low proton affinities of radical anion 2 and suggest that the pK(a) of radical [2+H] might be lower than 6. Implications are discussed regarding the formation of hydroxyl from 3 and/or 4, regarding the ability of 5 and 6 to react with carbon-centered radicals in a manner that ultimately leads to oxygen transfer, and regarding the interpretation of the EPR spectra of reduced TPZ species and of their spin-trap adducts.
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Affiliation(s)
- Jian Yin
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, USA
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Cimmino A, Evidente A, Mathieu V, Andolfi A, Lefranc F, Kornienko A, Kiss R. Phenazines and cancer. Nat Prod Rep 2012; 29:487-501. [DOI: 10.1039/c2np00079b] [Citation(s) in RCA: 85] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
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