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Flores ADR, Barber CC, Narayanamoorthy M, Gu D, Shen Y, Zhang W. Biosynthesis of Isonitrile- and Alkyne-Containing Natural Products. Annu Rev Chem Biomol Eng 2022; 13:1-24. [PMID: 35236086 PMCID: PMC9811556 DOI: 10.1146/annurev-chembioeng-092120-025140] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
Abstract
Natural products are a diverse class of biologically produced compounds that participate in fundamental biological processes such as cell signaling, nutrient acquisition, and interference competition. Unique triple-bond functionalities like isonitriles and alkynes often drive bioactivity and may serve as indicators of novel chemical logic and enzymatic machinery. Yet, the biosynthetic underpinnings of these groups remain only partially understood, constraining the opportunity to rationally engineer biomolecules with these functionalities for applications in pharmaceuticals, bioorthogonal chemistry, and other value-added chemical processes. Here, we focus our review on characterized biosynthetic pathways for isonitrile and alkyne functionalities, their bioorthogonal transformations, and prospects for engineering their biosynthetic machinery for biotechnological applications.
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Affiliation(s)
- Antonio Del Rio Flores
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California, USA
| | - Colin C. Barber
- Department of Plant and Microbial Biology, University of California, Berkeley, California, USA
| | | | - Di Gu
- Department of Chemistry, University of California, Berkeley, California, USA
| | - Yuanbo Shen
- Department of Chemistry, University of California, Berkeley, California, USA
| | - Wenjun Zhang
- Department of Chemical and Biomolecular Engineering, University of California, Berkeley, California, USA,Chan Zuckerberg Biohub, San Francisco, California, USA
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2
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Elmassry MM, Bisht K, Colmer-Hamood JA, Wakeman CA, San Francisco MJ, Hamood AN. Malonate utilization by Pseudomonas aeruginosa affects quorum-sensing and virulence and leads to formation of mineralized biofilm-like structures. Mol Microbiol 2021; 116:516-537. [PMID: 33892520 DOI: 10.1111/mmi.14729] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2021] [Revised: 04/06/2021] [Accepted: 04/16/2021] [Indexed: 01/02/2023]
Abstract
Pseudomonas aeruginosa is an opportunistic pathogen that uses malonate among its many carbon sources. We recently reported that, when grown in blood from trauma patients, P. aeruginosa expression of malonate utilization genes was upregulated. In this study, we explored the role of malonate utilization and its contribution to P. aeruginosa virulence. We grew P. aeruginosa strain PA14 in M9 minimal medium containing malonate (MM9) or glycerol (GM9) as a sole carbon source and assessed the effect of the growth on quorum sensing, virulence factors, and antibiotic resistance. Growth of PA14 in MM9, compared to GM9, reduced the production of elastases, rhamnolipids, and pyoverdine; enhanced the production of pyocyanin and catalase; and increased its sensitivity to norfloxacin. Growth in MM9 decreased extracellular levels of N-acylhomoserine lactone autoinducers, an effect likely associated with increased pH of the culture medium; but had little effect on extracellular levels of PQS. At 18 hr of growth in MM9, PA14 formed biofilm-like structures or aggregates that were associated with biomineralization, which was related to increased pH of the culture medium. These results suggest that malonate significantly impacts P. aeruginosa pathogenesis by influencing the quorum sensing systems, the production of virulence factors, biofilm formation, and antibiotic resistance.
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Affiliation(s)
- Moamen M Elmassry
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Karishma Bisht
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA
| | - Jane A Colmer-Hamood
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Department of Medical Education, Texas Tech University Health Sciences Center, Lubbock, TX, USA
| | | | - Michael J San Francisco
- Department of Biological Sciences, Texas Tech University, Lubbock, TX, USA.,Honors College, Texas Tech University, Lubbock, TX, USA
| | - Abdul N Hamood
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, USA.,Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, TX, USA
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Chen TY, Chen J, Tang Y, Zhou J, Guo Y, Chang WC. Current Understanding toward Isonitrile Group Biosynthesis and Mechanism. CHINESE J CHEM 2021; 39:463-472. [PMID: 34658601 PMCID: PMC8519408 DOI: 10.1002/cjoc.202000448] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2020] [Accepted: 09/21/2020] [Indexed: 12/20/2022]
Abstract
Isonitrile group has been identified in many natural products. Due to the broad reactivity of N≡C triple bond, these natural products have valuable pharmaceutical potentials. This review summarizes the current biosynthetic pathways and the corresponding enzymes that are responsible for isonitrile-containing natural product generation. Based on the strategies utilized, two fundamentally distinctive approaches are discussed. In addition, recent progress in elucidating isonitrile group formation mechanisms is also presented.
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Affiliation(s)
- Tzu-Yu Chen
- Department of Chemistry, North Carolina State University Raleigh, NC 27695, U.S.A
| | - Jinfeng Chen
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai 200032, China
| | - Yijie Tang
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, U.S.A
| | - Jiahai Zhou
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Center for Excellence in Molecular Synthesis, Shanghai Institute of Organic Chemistry, University of Chinese Academy of Sciences, Shanghai 200032, China
- CAS Key Laboratory of Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, Guangdong 518055, China
| | - Yisong Guo
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, U.S.A
| | - Wei-chen Chang
- Department of Chemistry, North Carolina State University Raleigh, NC 27695, U.S.A
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4
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Sivakumar R, Gunasekaran P, Rajendhran J. Functional characterization of asnC family transcriptional regulator in Pseudomonas aeruginosa PGPR2 during root colonization. Mol Biol Rep 2020; 47:7941-7957. [PMID: 33011891 DOI: 10.1007/s11033-020-05872-y] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Accepted: 09/28/2020] [Indexed: 12/18/2022]
Abstract
Transcriptional regulators in bacteria are the crucial players in mediating communication between environmental cues and DNA transcription through a complex network process. Pseudomonas aeruginosa PGPR2 is an efficient root colonizer and a biocontrol strain. Previously, we identified that the transcriptional regulator, asnC, negatively regulates the corn root colonization of P. aeruginosa PGPR2. In a transposon insertion sequencing (INSeq) screen, the asnC insertion mutant was positively selected during root colonization, meaning the disruption of asnC improves the fitness of the P. aeruginosa PGPR2 strain for the root colonization. In this study, we constructed isogenic mutant of asnC family transcriptional regulator encoded by PGPR2_17510 by allele exchange mutagenesis. The ΔasnC mutant was able to efficiently colonize corn roots with a twofold increase in population when compared to the wild-type strain. Similarly, the mutant strain outcompeted the wild-type strain in a competition assay, where the mutant strain represented 90% of the total population recovered from the root. We compared the whole transcriptome of the wild-type and the ΔasnC mutant of P. aeruginosa PGPR2 when exposed to the corn root exudates. The RNA-Seq revealed that a total of 360 genes were differentially expressed in the ΔasnC strain of P. aeruginosa PGPR2. Inactivation of asnC transcriptional regulator resulted in the up-regulation of several genetic factors implicated in metabolism, uptake of nutrients, motility, stress response, and signal transduction, which could play crucial roles in root colonization. This notion was further validated by phenotypic characterization and quantification of transcription pattern of selected genes associated with metabolism, motility, and carbon catabolite repression between wild type and mutant strain, which was in agreement with transcriptome data. Similarly, ΔasnC strain formed increased biofilm on abiotic surface validating our RNA-seq analysis, where transcript levels of several genes associated with biofilm formation were up-regulated in the mutant strain. We report that the inactivation of an asnC family transcriptional regulator encoded by PGPR2_17510 enhances the root colonization and biofilm-forming ability of P. aeruginosa PGPR2. Together, our results provide evidence for the molecular adaptations that enable ΔasnC mutant strain to colonize on the corn roots and to form a biofilm.
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Affiliation(s)
- Ramamoorthy Sivakumar
- Department of Genetics, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, India
| | | | - Jeyaprakash Rajendhran
- Department of Genetics, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, India.
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Iftikhar A, Asif A, Manzoor A, Azeem M, Sarwar G, Rashid N, Qaisar U. Mutation in pvcABCD operon of Pseudomonas aeruginosa modulates MexEF-OprN efflux system and hence resistance to chloramphenicol and ciprofloxacin. Microb Pathog 2020; 149:104491. [PMID: 32941967 DOI: 10.1016/j.micpath.2020.104491] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2020] [Revised: 09/05/2020] [Accepted: 09/05/2020] [Indexed: 11/17/2022]
Abstract
Pseudomonas aeruginosa harbors pvcABCD operon that is responsible for the synthesis of paerucumarin. Here we report the involvement of pvcABCD operon in chloramphenicol and ciprofloxacin resistance. P. aeruginosa mutant defective in pvcB (PW4832) was more sensitive to chloramphenicol and ciprofloxacin in comparison with its parent strain (MPAO1). A mutation in pvcA gene in MPAO1 (PW4830) did not alter the sensitivity to either antibiotic. As chloramphenicol and ciprofloxacin are substrates of MexEF-OprN efflux pump, so we decided to investigate the modulation of MexEF-OprN and its transcriptional regulator MexT in PW4832, PW4830 and MPAO1 strains. We isolated and sequenced mexT gene from MPAO1, PW4830 and PW4832. The nucleotide sequence of mexT gene in all three strains was identical. Expression levels of mexEF-oprN, mexT and mexS genes were checked via quantitative real-time RT-PCR. All these genes showed significant repression in mRNA levels in PW4832 as compared to MPAO1. These results indicate that chloramphenicol and ciprofloxacin sensitivity in PW4832 is due to transcriptional repression of mexT and mexEF-oprN genes. Exogenous addition of paerucumarin resumed the expression of mexT and mexEF-oprN genes as well as resistance against chloramphenicol and ciprofloxacin in PW4832 strain. This is a novel finding linking pvcB gene of P. aeruginosa with chloramphenicol and ciprofloxacin resistance and MexEF-OprN pump modulation which needs to be further explored.
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Affiliation(s)
- Anam Iftikhar
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Azka Asif
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Asma Manzoor
- Institute of Biochemistry and Biotechnology, University of the Punjab, Lahore, Pakistan
| | - Muhammad Azeem
- Botany Department, Government College University, Faisalabad, Pakistan
| | - Ghulam Sarwar
- Cotton Research Station, Ayub Agriculture Research Institute, Faisalabad, Pakistan
| | - Naeem Rashid
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Uzma Qaisar
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan.
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6
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Abstract
Natural products from microorganisms are important small molecules that play roles in various biological processes like cellular growth, motility, nutrient acquisition, stress response, biofilm formation, and defense. It is hypothesized that pathogens exploit these molecules to regulate virulence and persistence during infections. Here, we present selected examples of signaling natural products from human pathogenic bacteria that use these metabolites to gain a competitive advantage. Targeting these signaling systems provides novel strategies to antimicrobial treatments.
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Affiliation(s)
- Zhijuan Hu
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, 201 Gilman Hall, Berkeley, California 94720, United States
| | - Wenjun Zhang
- Department of Chemical and Biomolecular Engineering, University of California Berkeley, 201 Gilman Hall, Berkeley, California 94720, United States
- Chan Zuckerberg Biohub, San Francisco, California 94158, United States
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Asif A, Iftikhar A, Hamood A, Colmer-Hamood JA, Qaisar U. Isonitrile-functionalized tyrosine modulates swarming motility and quorum sensing in Pseudomonas aeruginosa. Microb Pathog 2018; 127:288-295. [PMID: 30528249 DOI: 10.1016/j.micpath.2018.12.001] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2018] [Revised: 12/02/2018] [Accepted: 12/03/2018] [Indexed: 11/16/2022]
Abstract
Paerucumarin synthesized by pvc operon pvcABCD is an iron binding molecule which modulates biofilm formation in Pseudomonas aeruginosa but its direct function in bacterial pathogenesis needs further investigation. pvcA synthesizes isonitrile functionalized tyrosine (IFT) which is converted to mature paerucumarin by the proteins encoded by pvcB, pvcC and pvcD genes. Interruption of pvcB in MPAO1 resulted in accumulation of IFT as it cannot be converted to mature molecule. The MPAO1 pvcB mutant (PW4832) showed enhanced swarming motility, while complementation with plasmid pLL2 carrying pvcB reduced swarming motility. Enhanced levels of rhlA expression and rhamnolipid production were observed in PW4832 compared to the parent strain. Overexpression of ptxR, the positive regulator of pvcABCD, in PW4832 caused accumulation of more IFT and further elevated the level of rhlA expression. Expression of the quorum sensing system transcriptional activators lasR and rhlR, as well as the synthase genes lasI and rhlI, was enhanced in PW4832 compared to MPAO1, as was PQS accumulation. Exogenously added IFT, but not paerucumarin, enhanced the production of rhamnolipids in P. aeruginosa. These results suggest that IFT enhances swarming motility in P. aeruginosa either directly by enhancing rhamnolipid production or indirectly through modulation of the quorum sensing systems. This is the first report assigning an independent function to IFT in P. aeruginosa.
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Affiliation(s)
- Azka Asif
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Anam Iftikhar
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan
| | - Abdul Hamood
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Jane A Colmer-Hamood
- Department of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA; Department of Medical Education, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Uzma Qaisar
- School of Biological Sciences, University of the Punjab, Lahore, Pakistan.
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Isolation and characterization of HepP: a virulence-related Pseudomonas aeruginosa heparinase. BMC Microbiol 2017; 17:233. [PMID: 29246112 PMCID: PMC5732420 DOI: 10.1186/s12866-017-1141-0] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Accepted: 12/05/2017] [Indexed: 12/15/2022] Open
Abstract
Background Pseudomonas aeruginosa is an opportunistic pathogen that causes serious infections in immunocompromised hosts including severely burned patients. In burn patients, P. aeruginosa infection often leads to septic shock and death. Despite numerous studies, the influence of severe thermal injuries on the pathogenesis of P. aeruginosa during systemic infection is not known. Through RNA-seq analysis, we recently showed that the growth of P. aeruginosa strain UCBPP-PA14 (PA14) in whole blood obtained from severely burned patients significantly altered the expression of the PA14 transcriptome when compared with its growth in blood from healthy volunteers. The expression of PA14_23430 and the adjacent gene, PA14_23420, was enhanced by seven- to eightfold under these conditions. Results Quantitative real-time PCR analysis confirmed the enhancement of expression of both PA14_23420 and PA14_23430 by growth of PA14 in blood from severely burned patients. Computer analysis revealed that PA14_23430 (hepP) encodes a potential heparinase while PA14_23420 (zbdP) codes for a putative zinc-binding dehydrogenase. This analysis further suggested that the two genes form an operon with zbdP first. Presence of the operon was confirmed by RT-PCR experiments. We characterized hepP and its protein product HepP. hepP was cloned from PA14 by PCR and overexpressed in E. coli. The recombinant protein (rHepP) was purified using nickel column chromatography. Heparinase assays using commercially available heparinase as a positive control, revealed that rHepP exhibits heparinase activity. Mutation of hepP resulted in delay of pellicle formation at the air-liquid interface by PA14 under static growth conditions. Biofilm formation by PA14ΔhepP was also significantly reduced. In the Caenorhabditis elegans model of slow killing, mutation of hepP resulted in a significantly lower rate of killing than that of the parent strain PA14. Conclusions Changes within the blood of severely burned patients significantly induced expression of hepP in PA14. The heparinase encoded by hepP is a potential virulence factor for PA14 as HepP influences pellicle formation as well as biofilm development by PA14 and the protein is required for full virulence in the C. elegans model of slow killing. Electronic supplementary material The online version of this article (10.1186/s12866-017-1141-0) contains supplementary material, which is available to authorized users.
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Lin CS, Tsai YH, Chang CJ, Tseng SF, Wu TR, Lu CC, Wu TS, Lu JJ, Horng JT, Martel J, Ojcius DM, Lai HC, Young JD. An iron detection system determines bacterial swarming initiation and biofilm formation. Sci Rep 2016; 6:36747. [PMID: 27845335 PMCID: PMC5109203 DOI: 10.1038/srep36747] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2016] [Accepted: 10/20/2016] [Indexed: 11/30/2022] Open
Abstract
Iron availability affects swarming and biofilm formation in various bacterial species. However, how bacteria sense iron and coordinate swarming and biofilm formation remains unclear. Using Serratia marcescens as a model organism, we identify here a stage-specific iron-regulatory machinery comprising a two-component system (TCS) and the TCS-regulated iron chelator 2-isocyano-6,7-dihydroxycoumarin (ICDH-Coumarin) that directly senses and modulates environmental ferric iron (Fe3+) availability to determine swarming initiation and biofilm formation. We demonstrate that the two-component system RssA-RssB (RssAB) directly senses environmental ferric iron (Fe3+) and transcriptionally modulates biosynthesis of flagella and the iron chelator ICDH-Coumarin whose production requires the pvc cluster. Addition of Fe3+, or loss of ICDH-Coumarin due to pvc deletion results in prolonged RssAB signaling activation, leading to delayed swarming initiation and increased biofilm formation. We further show that ICDH-Coumarin is able to chelate Fe3+ to switch off RssAB signaling, triggering swarming initiation and biofilm reduction. Our findings reveal a novel cellular system that senses iron levels to regulate bacterial surface lifestyle.
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Affiliation(s)
- Chuan-Sheng Lin
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Department of Biochemistry and Molecular Biology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Research Center of Bacterial Pathogenesis, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Yu-Huan Tsai
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Chih-Jung Chang
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Shun-Fu Tseng
- Research Center of Bacterial Pathogenesis, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Tsung-Ru Wu
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Chia-Chen Lu
- Department of Respiratory Therapy, Fu Jen University, New Taipei City, Taiwan, Republic of China
| | - Ting-Shu Wu
- Department of Internal Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan, Republic of China
| | - Jang-Jih Lu
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan, Republic of China
| | - Jim-Tong Horng
- Department of Biochemistry and Molecular Biology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - Jan Martel
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
| | - David M. Ojcius
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Department of Biomedical Sciences, University of the Pacific, Arthur Dugoni School of Dentistry, San Francisco, United States of America
| | - Hsin-Chih Lai
- Department of Medical Biotechnology and Laboratory Science, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Research Center of Bacterial Pathogenesis, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Department of Laboratory Medicine, Chang Gung Memorial Hospital, Taoyuan, Taiwan, Republic of China
- Research Center for Industry of Human Ecology, Chang Gung University of Science and Technology, Taoyuan, Taiwan, Republic of China
- Graduate Institute of Health Industry Technology, Chang Gung University of Science and Technology, Taoyuan, Taiwan, Republic of China
| | - John D. Young
- Center for Molecular and Clinical Immunology, Chang Gung University, Taoyuan, Taiwan, Republic of China
- Laboratory of Cellular Physiology and Immunology, Rockefeller University, New York, United States of America
- Biochemical Engineering Research Center, Ming Chi University of Technology, New Taipei City, Taiwan, Republic of China
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10
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Qaisar U, Kruczek CJ, Azeem M, Javaid N, Colmer-Hamood JA, Hamood AN. The Pseudomonas aeruginosa extracellular secondary metabolite, Paerucumarin, chelates iron and is not localized to extracellular membrane vesicles. J Microbiol 2016; 54:573-81. [PMID: 27480638 DOI: 10.1007/s12275-016-5645-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Revised: 05/31/2016] [Accepted: 07/01/2016] [Indexed: 10/21/2022]
Abstract
Proteins encoded by the Pseudomonas aeruginosa pvcA-D operon synthesize a novel isonitrile functionalized cumarin termed paerucumarin. The pvcA-D operon enhances the expression of the P. aeruginosa fimbrial chaperone/usher pathway (cup) genes and this effect is mediated through paerucumarin. Whether pvcA-D and/or paerucumarin affect the expression of other P. aeruginosa genes is not known. In this study, we examined the effect of a mutation in pvcA-D operon the global transcriptome of the P. aeruginosa strain PAO1-UW. The mutation reduced the expression of several ironcontrolled genes including pvdS, which is essential for the expression of the pyoverdine genes. Additional transcriptional studies showed that the pvcA-D operon is not regulated by iron. Exogenously added paerucumarin enhanced pyoverdine production and pvdS expression in PAO1-UW. Iron-chelation experiments revealed that purified paerucumarin chelates iron. However, exogenously added paerucumarin significantly reduced the growth of a P. aeruginosa mutant defective in pyoverdine and pyochelin production. In contrast to other secondary metabolite, Pseudomonas quinolone signal (PQS), paerucumarin is not localized to the P. aeruginosa membrane vesicles. These results suggest that paerucumarin enhances the expression of iron-controlled genes by chelating iron within the P. aeruginosa extracellular environment. Although paerucumarin chelates iron, it does not function as a siderophore. Unlike PQS, paerucumarin is not associated with the P. aeruginosa cell envelope.
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Affiliation(s)
- Uzma Qaisar
- Departments of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA. .,School of Biological Sciences, University of the Punjab, Lahore, 54590, Pakistan.
| | - Cassandra J Kruczek
- Surgery Department, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Muhammed Azeem
- Botany Department, Government College University, Faisalabad, 38000, Pakistan
| | - Nasir Javaid
- School of Biological Sciences, University of the Punjab, Lahore, 54590, Pakistan
| | - Jane A Colmer-Hamood
- Departments of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA.,Medical Education, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
| | - Abdul N Hamood
- Departments of Immunology and Molecular Microbiology, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA.,Surgery Department, Texas Tech University Health Sciences Center, Lubbock, TX, 79430, USA
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11
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Zhu J, Lippa GM, Gulick AM, Tipton PA. Examining Reaction Specificity in PvcB, a Source of Diversity in Isonitrile-Containing Natural Products. Biochemistry 2015; 54:2659-69. [PMID: 25866990 DOI: 10.1021/acs.biochem.5b00255] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Many bacteria produce isonitrile-containing natural products that are derived from aromatic amino acids. The synthetic clusters that control biosynthesis most commonly encode two enzymes, designated PvcA and PvcB, as well as additional enzymes that direct synthesis of the natural product. The PvcA enzyme installs the isonitrile moiety at the amino group of either tyrosine or tryptophan, as dictated by the particular pathway. The common pathway intermediate produced by PvcA is directed toward different ultimate products by PvcB, a member of the family of Fe(2+), α-ketoglutarate-dependent oxygenases. To continue our investigation of the structural and functional properties of the isonitrile biosynthetic pathways, we present here a study of the PvcB homologues from three organisms. Two pathways, derived from Pseudomonas aeruginosa and Xenorhabdus nematophila, produce known products. A third PvcB homologue from Erwinia amylovora is part of an uncharacterized pathway. Our results demonstrate the diversity of reactions catalyzed. Although all PvcB enzymes catalyze the hydroxylation of the tyrosine isonitrile substrate, the elimination of the hydroxyl in Pseudomonas and Erwinia is driven by deprotonation at Cα, resulting in the initial production of an unsaturated tyrosine isonitrile product that then cyclizes to a coumarin derivative. PvcB from Xenorhabdus, in contrast, catalyzes the same oxygenation, but loss of the hydroxyl group is accompanied by decarboxylation of the intermediate. Steady-state kinetic analysis of the three reactions and a docking model for the binding of the tyrosine isonitrile substrate in the PvcB active site highlight subtle differences between the PvcB homologues.
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Affiliation(s)
- Jing Zhu
- †Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Geoffrey M Lippa
- ‡Hauptman-Woodward Medical Research Foundation, Buffalo, New York 14203, United States
| | - Andrew M Gulick
- ‡Hauptman-Woodward Medical Research Foundation, Buffalo, New York 14203, United States.,§Department of Structural Biology, University at Buffalo, Buffalo, New York 14203, United States
| | - Peter A Tipton
- †Department of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
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12
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Polyphenolic extract from maple syrup potentiates antibiotic susceptibility and reduces biofilm formation of pathogenic bacteria. Appl Environ Microbiol 2015; 81:3782-92. [PMID: 25819960 DOI: 10.1128/aem.00239-15] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2015] [Accepted: 03/23/2015] [Indexed: 12/21/2022] Open
Abstract
Phenolic compounds are believed to be promising candidates as complementary therapeutics. Maple syrup, prepared by concentrating the sap from the North American maple tree, is a rich source of natural and process-derived phenolic compounds. In this work, we report the antimicrobial activity of a phenolic-rich maple syrup extract (PRMSE). PRMSE exhibited antimicrobial activity as well as strong synergistic interaction with selected antibiotics against Gram-negative clinical strains of Escherichia coli, Proteus mirabilis, and Pseudomonas aeruginosa. Among the phenolic constituents of PRMSE, catechol exhibited strong synergy with antibiotics as well as with other phenolic components of PRMSE against bacterial growth. At sublethal concentrations, PRMSE and catechol efficiently reduced biofilm formation and increased the susceptibility of bacterial biofilms to antibiotics. In an effort to elucidate the mechanism for the observed synergy with antibiotics, PRMSE was found to increase outer membrane permeability of all bacterial strains and effectively inhibit efflux pump activity. Furthermore, transcriptome analysis revealed that PRMSE significantly repressed multiple-drug resistance genes as well as genes associated with motility, adhesion, biofilm formation, and virulence. Overall, this study provides a proof of concept and starting point for investigating the molecular mechanism of the reported increase in bacterial antibiotic susceptibility in the presence of PRMSE.
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Identification of a putative flavin adenine dinucleotide-binding monooxygenase as a regulator for Myxococcus xanthus development. J Bacteriol 2015; 197:1185-96. [PMID: 25605309 DOI: 10.1128/jb.02555-14] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022] Open
Abstract
UNLABELLED Gene clusters coding for the chaperone/usher (CU) pathway are widely distributed in many important environmental and pathogenic microbes; however, information about the regulatory machineries controlling CU gene expression during multicellular morphogenesis is missing. The Myxococcus xanthus Mcu system, encoded by the mcuABCD gene cluster, represents a prototype of the archaic CU family that functions in spore coat formation. Using genome-wide transposon mutagenesis, we identified MXAN2872 to be a potential regulator of the mcuABC operon and demonstrated the necessity of MXAN2872 for mcuABC expression and fruiting body morphogenesis in early development. In silico, biochemical, and genetic analyses suggest that MXAN2872 encodes a Baeyer-Villiger monooxygenase (BVMO) of flavoproteins, and the potential cofactor-binding site as well as the BVMO fingerprint sequence is important for the regulatory role of the MXAN2872 protein. The expression profile of mcuA in strains with an MXAN2872 deletion and point mutation agrees well with the timing of cell aggregation of these mutants. Furthermore, McuA could not be detected either in a fruA-null mutant, where starvation-induced aggregation was completely blocked, or in the glycerol-induced spores, where sporulation was uncoupled from cell aggregation. In sum, the present work uncovers a positive role for MXAN2872, a metabolic enzyme-encoding gene, in controlling M. xanthus development. MXAN2872 functions by affecting the onset of cell aggregation, thereby leading to a secondary effect on the timing of mcuABC expression of this model organism. IMPORTANCE Identification of the players that drive Myxococcus xanthus fruiting body formation is necessary for studying the mechanism of multicellular morphogenesis in this model organism. This study identifies MXAN2872, a gene encoding a putative flavin adenine dinucleotide-binding monooxygenase, to be a new interesting regulator regulating the timing of developmental aggregation. In addition, MXAN2872 seems to affect the expression of the chaperone/usher gene cluster mcu in a manner that is aggregation dependent. Thus, in organisms characterized by a developmental cycle, expression of the chaperone/usher pathway can be controlled by morphological checkpoints, demonstrating another layer of complexity in the regulation of this conserved protein secretion pathway.
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Mikkelsen H, Hui K, Barraud N, Filloux A. The pathogenicity island encoded PvrSR/RcsCB regulatory network controls biofilm formation and dispersal in Pseudomonas aeruginosa PA14. Mol Microbiol 2013; 89:450-63. [PMID: 23750818 PMCID: PMC3842833 DOI: 10.1111/mmi.12287] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/03/2013] [Indexed: 01/14/2023]
Abstract
Pseudomonas aeruginosa biofilm formation is linked to persistent infections in humans. Biofilm formation is facilitated by extracellular appendages, some of which are assembled by the Chaperone Usher Pathway (Cup). The cupD gene cluster is located on the PAPI-1 pathogenicity island of strain PA14 and has probably been acquired together with four genes encoding two-component signal transduction proteins. We have previously showed that the RcsB response regulator activates expression of the cupD genes, which leads to the production of CupD fimbriae and increased attachment. Here we show that RcsB activity is tightly modulated by two sensors, RcsC and PvrS. While PvrS acts as a kinase that enhances RcsB activity, RcsC has a dual function, first as a phosphorelay, and second as a phosphatase. We found that, under certain growth conditions, overexpression of RcsB readily induces biofilm dispersal. Microarray analysis shows that RcsB positively controls expression of pvrR that encodes the phosphodiesterase required for this dispersal process. Finally, in addition to the PAPI-1 encoded cupD genes, RcsB controls several genes on the core genome, some of which encode orphan response regulators. We thus discovered that RcsB is central to a large regulatory network that fine-tunes the switch between biofilm formation and dispersal.
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Affiliation(s)
- Helga Mikkelsen
- Imperial College London, Department of Life Sciences, MRC Centre for Molecular Bacteriology and Infection, South Kensington Campus, Flowers Building, SW7 2AZ, London, UK
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