The Experts below are selected from a list of 201 Experts worldwide ranked by ideXlab platform
Zixin Deng - One of the best experts on this subject based on the ideXlab platform.
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an unusual ump c 5 methylase in nucleoside antibiotic polyoxin biosynthesis
Protein & Cell, 2016Co-Authors: Wenqing Chen, Zixin Deng, Renxiao Wang, Jiahai ZhouAbstract:Polyoxin is a group of structurally-related peptidyl nucleoside antibiotics bearing C-5 modifications on the nucleoside skeleton. Although the structural diversity and bioactivity preference of polyoxin are, to some extent, affected by such modifications, the biosynthetic logic for their occurence remains obscure. Here we report the identification of PolB in polyoxin pathway as an unusual UMP C-5 methylase with thymidylate synthase activity which is responsible for the C-5 methylation of the nucleoside skeleton. To probe its molecular mechanism, we determined the crystal structures of PolB alone and in complexes with 5-Br UMP and 5-Br dUMP at 2.15 A, 1.76 A and 2.28 A resolutions, respectively. Loop 1 (residues 117-131), Loop 2 (residues 192-201) and the substrate recognition peptide (residues 94-102) of PolB exhibit considerable conformational flexibility and adopt distinct structures upon binding to different substrate analogs. Consistent with the structural findings, a PolB homolog that harbors an identical function from Streptomyces viridochromogenes DSM 40736 was identified. The discovery of UMP C5-methylase opens the way to rational pathway engineering for polyoxin component optimization, and will also enrich the toolbox for natural nucleotide chemistry.
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metabolic engineering of an industrial polyoxin producer for the targeted overproduction of designer nucleoside antibiotics
Biotechnology and Bioengineering, 2015Co-Authors: Jin Liu, Dan Wan, Yousheng Cai, Yinghu Wang, Xuan Feng, Guofu Qiu, Shengping Yang, Wenqing Chen, Zixin DengAbstract:Polyoxin and nikkomycin are naturally occurring peptidyl nucleoside antibiotics with potent antifungal bioactivity. Both exhibit similar structural features, having a nucleoside skeleton and one or two peptidyl moieties. Combining the refactoring of the polyoxin producer Streptomyces aureochromogenes with import of the hydroxypyridylhomothreonine pathway of nikkomycin allows the targeted production of three designer nucleoside antibiotics designated as nikkoxin E, F, and G. These structures were determined by NMR and/or high resolution mass spectrometry. Remarkably, the introduction of an extra copy of the nikS gene encoding an ATP-dependent ligase significantly enhanced the production of the designer antibiotics. Moreover, all three nikkoxins displayed improved bioactivity against several pathogenic fungi as compared with the naturally-occurring antibiotics. These data provide a feasible model for high efficiency generation of nucleoside antibiotics related to Polyoxins and nikkomycins in a polyoxin cell factory via synthetic biology strategy.
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Genetic dissection of the polyoxin building block-carbamoylpolyoxamic acid biosynthesis revealing the “pathway redundancy” in metabolic networks
Microbial cell factories, 2013Co-Authors: Wenqing Chen, Lipeng Zhai, Tingting Huang, Daofeng Dai, Changchun Wang, Zixin DengAbstract:Polyoxin, a peptidyl nucleoside antibiotic, consists of three building blocks including a nucleoside skeleton, polyoximic acid (POIA), and carbamoylpolyoxamic acid (CPOAA), however, little is known about the “pathway redundancy” of the metabolic networks directing the CPOAA biosynthesis in the cell factories of the polyoxin producer. Here we report the genetic characterization of CPOAA biosynthesis with revealing a “pathway redundancy” in metabolic networks. Independent mutation of the four genes (polL-N and polP) directly resulted in the accumulation of polyoxin I, suggesting their positive roles for CPOAA biosynthesis. Moreover, the individual mutant of polN and polP also partially retains polyoxin production, suggesting the existence of the alternative homologs substituting their functional roles. It is unveiled that argA and argB in L-arginine biosynthetic pathway contributed to the “pathway redundancy”, more interestingly, argB in S. cacaoi is indispensible for both polyoxin production and L-arginine biosynthesis. These data should provide an example for the research on the “pathway redundancy” in metabolic networks, and lay a solid foundation for targeted enhancement of polyoxin production with synthetic biology strategies.
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Engineering of an industrial polyoxin producer for the rational production of hybrid peptidyl nucleoside antibiotics.
Metabolic engineering, 2012Co-Authors: Lipeng Zhai, Wenqing Chen, Shuangjun Lin, Xuechuan Hong, Linquan Bai, Zixin DengAbstract:Polyoxins and nikkomycins are potent antifungal peptidyl nucleoside antibiotics, which inhibit fungal cell wall biosynthesis. They consist of a nucleoside core and one or two independent peptidyl moieties attached to the core at different sites. Making mutations and introducing heterologous genes into an industrial Streptomyces aureochromogenes polyoxin producer, resulted in the production of four polyoxin-nikkomycin hybrid antibiotics designated as polyoxin N and nikkoxin B-D, whose structures were confirmed using high resolution MS and NMR. Two of the hybrid antibiotics, polyoxin N and nikkoxin D, were significantly more potent against some human or plant fungal pathogens than their parents. The data provides an example for rational generation of novel peptidyl nucleoside antibiotics in an industrial producer.
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Enhancement of the diversity of Polyoxins by a thymine-7-hydroxylase homolog outside the polyoxin biosynthesis gene cluster.
Applied and environmental microbiology, 2010Co-Authors: Changming Zhao, Wenqing Chen, Tingting Huang, Zixin DengAbstract:Polyoxins consist of 14 structurally variable components which differentiate at three branch sites of the carbon skeleton. Open reading frame (ORF) SAV_4805 of Streptomyces avermitilis, showing similarity to thymine-7-hydroxylase, was proved to enhance the diversity of Polyoxins at the C-5 site of the 1-(5′-amino-5′-deoxy-β-d-allofuranuronosyl) pyrimidine moiety.
Wenqing Chen - One of the best experts on this subject based on the ideXlab platform.
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an unusual ump c 5 methylase in nucleoside antibiotic polyoxin biosynthesis
Protein & Cell, 2016Co-Authors: Wenqing Chen, Zixin Deng, Renxiao Wang, Jiahai ZhouAbstract:Polyoxin is a group of structurally-related peptidyl nucleoside antibiotics bearing C-5 modifications on the nucleoside skeleton. Although the structural diversity and bioactivity preference of polyoxin are, to some extent, affected by such modifications, the biosynthetic logic for their occurence remains obscure. Here we report the identification of PolB in polyoxin pathway as an unusual UMP C-5 methylase with thymidylate synthase activity which is responsible for the C-5 methylation of the nucleoside skeleton. To probe its molecular mechanism, we determined the crystal structures of PolB alone and in complexes with 5-Br UMP and 5-Br dUMP at 2.15 A, 1.76 A and 2.28 A resolutions, respectively. Loop 1 (residues 117-131), Loop 2 (residues 192-201) and the substrate recognition peptide (residues 94-102) of PolB exhibit considerable conformational flexibility and adopt distinct structures upon binding to different substrate analogs. Consistent with the structural findings, a PolB homolog that harbors an identical function from Streptomyces viridochromogenes DSM 40736 was identified. The discovery of UMP C5-methylase opens the way to rational pathway engineering for polyoxin component optimization, and will also enrich the toolbox for natural nucleotide chemistry.
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metabolic engineering of an industrial polyoxin producer for the targeted overproduction of designer nucleoside antibiotics
Biotechnology and Bioengineering, 2015Co-Authors: Jin Liu, Dan Wan, Yousheng Cai, Yinghu Wang, Xuan Feng, Guofu Qiu, Shengping Yang, Wenqing Chen, Zixin DengAbstract:Polyoxin and nikkomycin are naturally occurring peptidyl nucleoside antibiotics with potent antifungal bioactivity. Both exhibit similar structural features, having a nucleoside skeleton and one or two peptidyl moieties. Combining the refactoring of the polyoxin producer Streptomyces aureochromogenes with import of the hydroxypyridylhomothreonine pathway of nikkomycin allows the targeted production of three designer nucleoside antibiotics designated as nikkoxin E, F, and G. These structures were determined by NMR and/or high resolution mass spectrometry. Remarkably, the introduction of an extra copy of the nikS gene encoding an ATP-dependent ligase significantly enhanced the production of the designer antibiotics. Moreover, all three nikkoxins displayed improved bioactivity against several pathogenic fungi as compared with the naturally-occurring antibiotics. These data provide a feasible model for high efficiency generation of nucleoside antibiotics related to Polyoxins and nikkomycins in a polyoxin cell factory via synthetic biology strategy.
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Genetic dissection of the polyoxin building block-carbamoylpolyoxamic acid biosynthesis revealing the “pathway redundancy” in metabolic networks
Microbial cell factories, 2013Co-Authors: Wenqing Chen, Lipeng Zhai, Tingting Huang, Daofeng Dai, Changchun Wang, Zixin DengAbstract:Polyoxin, a peptidyl nucleoside antibiotic, consists of three building blocks including a nucleoside skeleton, polyoximic acid (POIA), and carbamoylpolyoxamic acid (CPOAA), however, little is known about the “pathway redundancy” of the metabolic networks directing the CPOAA biosynthesis in the cell factories of the polyoxin producer. Here we report the genetic characterization of CPOAA biosynthesis with revealing a “pathway redundancy” in metabolic networks. Independent mutation of the four genes (polL-N and polP) directly resulted in the accumulation of polyoxin I, suggesting their positive roles for CPOAA biosynthesis. Moreover, the individual mutant of polN and polP also partially retains polyoxin production, suggesting the existence of the alternative homologs substituting their functional roles. It is unveiled that argA and argB in L-arginine biosynthetic pathway contributed to the “pathway redundancy”, more interestingly, argB in S. cacaoi is indispensible for both polyoxin production and L-arginine biosynthesis. These data should provide an example for the research on the “pathway redundancy” in metabolic networks, and lay a solid foundation for targeted enhancement of polyoxin production with synthetic biology strategies.
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Engineering of an industrial polyoxin producer for the rational production of hybrid peptidyl nucleoside antibiotics.
Metabolic engineering, 2012Co-Authors: Lipeng Zhai, Wenqing Chen, Shuangjun Lin, Xuechuan Hong, Linquan Bai, Zixin DengAbstract:Polyoxins and nikkomycins are potent antifungal peptidyl nucleoside antibiotics, which inhibit fungal cell wall biosynthesis. They consist of a nucleoside core and one or two independent peptidyl moieties attached to the core at different sites. Making mutations and introducing heterologous genes into an industrial Streptomyces aureochromogenes polyoxin producer, resulted in the production of four polyoxin-nikkomycin hybrid antibiotics designated as polyoxin N and nikkoxin B-D, whose structures were confirmed using high resolution MS and NMR. Two of the hybrid antibiotics, polyoxin N and nikkoxin D, were significantly more potent against some human or plant fungal pathogens than their parents. The data provides an example for rational generation of novel peptidyl nucleoside antibiotics in an industrial producer.
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Enhancement of the diversity of Polyoxins by a thymine-7-hydroxylase homolog outside the polyoxin biosynthesis gene cluster.
Applied and environmental microbiology, 2010Co-Authors: Changming Zhao, Wenqing Chen, Tingting Huang, Zixin DengAbstract:Polyoxins consist of 14 structurally variable components which differentiate at three branch sites of the carbon skeleton. Open reading frame (ORF) SAV_4805 of Streptomyces avermitilis, showing similarity to thymine-7-hydroxylase, was proved to enhance the diversity of Polyoxins at the C-5 site of the 1-(5′-amino-5′-deoxy-β-d-allofuranuronosyl) pyrimidine moiety.
Tingting Huang - One of the best experts on this subject based on the ideXlab platform.
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Genetic dissection of the polyoxin building block-carbamoylpolyoxamic acid biosynthesis revealing the “pathway redundancy” in metabolic networks
Microbial cell factories, 2013Co-Authors: Wenqing Chen, Lipeng Zhai, Tingting Huang, Daofeng Dai, Changchun Wang, Zixin DengAbstract:Polyoxin, a peptidyl nucleoside antibiotic, consists of three building blocks including a nucleoside skeleton, polyoximic acid (POIA), and carbamoylpolyoxamic acid (CPOAA), however, little is known about the “pathway redundancy” of the metabolic networks directing the CPOAA biosynthesis in the cell factories of the polyoxin producer. Here we report the genetic characterization of CPOAA biosynthesis with revealing a “pathway redundancy” in metabolic networks. Independent mutation of the four genes (polL-N and polP) directly resulted in the accumulation of polyoxin I, suggesting their positive roles for CPOAA biosynthesis. Moreover, the individual mutant of polN and polP also partially retains polyoxin production, suggesting the existence of the alternative homologs substituting their functional roles. It is unveiled that argA and argB in L-arginine biosynthetic pathway contributed to the “pathway redundancy”, more interestingly, argB in S. cacaoi is indispensible for both polyoxin production and L-arginine biosynthesis. These data should provide an example for the research on the “pathway redundancy” in metabolic networks, and lay a solid foundation for targeted enhancement of polyoxin production with synthetic biology strategies.
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Enhancement of the diversity of Polyoxins by a thymine-7-hydroxylase homolog outside the polyoxin biosynthesis gene cluster.
Applied and environmental microbiology, 2010Co-Authors: Changming Zhao, Wenqing Chen, Tingting Huang, Zixin DengAbstract:Polyoxins consist of 14 structurally variable components which differentiate at three branch sites of the carbon skeleton. Open reading frame (ORF) SAV_4805 of Streptomyces avermitilis, showing similarity to thymine-7-hydroxylase, was proved to enhance the diversity of Polyoxins at the C-5 site of the 1-(5′-amino-5′-deoxy-β-d-allofuranuronosyl) pyrimidine moiety.
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Characterization of the Polyoxin Biosynthetic Gene Cluster from Streptomyces cacaoi and Engineered Production of Polyoxin H
The Journal of biological chemistry, 2009Co-Authors: Wenqing Chen, Linquan Bai, Tingting Huang, Qingqing Meng, Delin You, Zhoujie XieAbstract:A gene cluster (pol) essential for the biosynthesis of polyoxin, a nucleoside antibiotic widely used for the control of phytopathogenic fungi, was cloned from Streptomyces cacaoi. A 46,066-bp region was sequenced, and 20 of 39 of the putative open reading frames were defined as necessary for polyoxin biosynthesis as evidenced by its production in a heterologous host, Streptomyces lividans TK24. The role of PolO and PolA in polyoxin synthesis was demonstrated by in vivo experiments, and their functions were unambiguously characterized as O-carbamoyltransferase and UMP-enolpyruvyltransferase, respectively, by in vitro experiments, which enabled the production of a modified compound differing slightly from that proposed earlier. These studies should provide a solid foundation for the elucidation of the molecular mechanisms for polyoxin biosynthesis, and set the stage for combinatorial biosynthesis using genes encoding different pathways for nucleoside antibiotics.
Yong Wang - One of the best experts on this subject based on the ideXlab platform.
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Total Synthesis of (+)-Polyoxin J.
The Journal of organic chemistry, 1999Co-Authors: Arun K. Ghosh, Yong WangAbstract:Stereoselective total synthesis of (+)-polyoxin J is described. The synthesis was achieved in a convergent manner by coupling protected thymine polyoxin C (19) and 5-O-carbamoyl polyoxamic acid 27 and subsequent removal of the protecting groups. The key steps of the synthesis of protected thymine polyoxin C involved the stereoselective electrophilic epoxidation of E-allyl alcohol 7 derived from isopropylidene d-ribose derivative 5, followed by regioselective epoxide opening of 8 and conversion of resulting azido diol 9 to protected thymine polyoxin C (19). Protected polyoxamic acid 27 was synthesized stereoselectively by utilizing Sharpless epoxidation of tartrate-derived allylic alcohol 20 followed by a regioselective epoxide ring opening with diisopropoxytitanium diazide.
Guido Schnabel - One of the best experts on this subject based on the ideXlab platform.
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CHALLENGES IN ASSESSING EFFICACY OF POLYOXIN-D ZINC SALT AGAINST COLLETOTRICHUM SPECIES
Journal of Plant Pathology, 2017Co-Authors: X.j. Hao, S.n. Chen, Guido SchnabelAbstract:Polyoxin-D zinc salt was recently made available for disease control of small fruit pathogens in the United States, but very little is known about its efficacy against diseases other than gray mold. In this study, the inhibitory activity of polyoxin-D zinc salt against Colletotrichum species from peach, the causal agent of peach fruit anthracnose, was assessed based on mycelial growth and germ tube elongation assays on four growth media, and in detached fruit assays. EC50 values between isolates of different Colletotrichum species varied within and between media for both mycelial growth and germ tube elongation tests. Occasionally, variability in sensitivity to polyoxin-D zinc salt was also found between isolates within the same species on the same media. Polyoxin-D zinc salt applied on detached fruit at recommended label rates inhibited mycelial growth of C. nymphaeae (100%), followed by C. fructicola (88.50%), C. siamense (78.97%), C. fioriniae-subgroup 2 (75.47%), C. fioriniaesubgroup 1 (73.55%), and C. truncatum (58.90%). In our assays, polyoxin-D zinc salt was equal or superior in efficacy compared to penthiopyrad. The results indicate that the EC50 values determined for Colletotrichum species is strongly dependent on the medium used and that none of the media accurately reflected observations on detached fruit assays.
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Characterization of Botrytis cinerea Isolates from Strawberry with Reduced Sensitivity to Polyoxin D Zinc Salt.
Plant disease, 2016Co-Authors: Madeline E. Dowling, Linus T. Schmitz, Jennifer R. Wilson, Guido SchnabelAbstract:Polyoxin D is a Fungicide Resistance Action Committee (FRAC) code 19 fungicide that was recently registered for gray mold control of strawberry in the United States. In this study, we determined the sensitivity to polyoxin D zinc salt (hereafter, polyoxin D) of Botrytis cinerea isolates from 41 commercial strawberry farms in South Carolina, North Carolina, Maryland, Virginia, and Ohio and investigated the fitness of sensitive (S) and reduced sensitive (RS) isolates. Relative mycelial growth ranged between 0 and over 100% on malt extract agar amended with a discriminatory dose of polyoxin D at 5 μg/ml. Isolates that grew more than 70% at that dose were designated RS and were found in three of the five states. The 50% effective dose (EC50) values of three S and three RS isolates ranged from 0.59 to 2.27 and 4.6 to 5.8 μg/ml, respectively. The three RS isolates grew faster on detached tomato fruit treated with Ph-D WDG at recommended label dosage than S isolates (P < 0.008). In all, 25 randomly selected RS i...