The role of Cercospora zeae-maydis homologs of Rhodobacter sphaeroides1O2-resistance genes in resistance to the photoactivated toxin cercosporin

Beseli, Aydin; Silva, Marília Goulart da; Daub, Margaret E.

doi:10.1093/femsle/fnu036

Cited by 6 publications

(10 citation statements)

References 52 publications

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“…The two plasmids were transformed into N . crassa as previously described [ 17 ]. Transformation and presence of 71cR or 24cF was confirmed in hyg-resistant colonies by PCR screening using gene specific primers (ToxA-Rev1 and 71cR-R, ToxA-Rev1 and 24cF-R, HYG-R and 71cR-F, HYG-R and 24cF-F) ( Table 2 ).…”

Section: Methodsmentioning

confidence: 99%

“…N . crassa 71cR and 24cF transformants were tested for cercosporin resistance as previously described [ 17 ]. Percent growth on medium containing 10 μM cercosporin was calculated relative to the acetone control on the same plate by measuring radial growth of colonies at 21 hours after inoculation.…”

Section: Methodsmentioning

confidence: 99%

“…Percent growth on medium containing 10 μM cercosporin was calculated relative to the acetone control on the same plate by measuring radial growth of colonies at 21 hours after inoculation. Total RNA was extracted from 4 randomly chosen transformants for gene expression analysis, and RT-qPCR analysis was conducted as previously described [ 17 ]. The N .…”

Section: Methodsmentioning

confidence: 99%

“…nicotianae B6 biosynthetic genes (PDX1 and PDX2), however, resulted in no statistically significant increase in levels of the B6 vitamers, due to heavy regulation of these genes in plants [ 16 ]. Although antioxidants have been implicated in cercosporin resistance [ 2 ], a recent study of a gene encoding glutathione S-transferase from the library failed to demonstrate a link with cercosporin resistance [ 17 ].…”

Section: Introductionmentioning

confidence: 99%

“…In Rhodobacter sphaeroides , a model for studies of 1 O 2 resistance, resistance is associated with protein synthesis and turnover, amino acid metabolism, and glutathione-dependent and–independent detoxification pathways, among others [ 2 ]. A recent study comparing putative resistance genes from our Cercospora subtractive library with orthologs identified in transcriptional studies of Rhodobacter 1 O 2 resistance, however, showed little commonality between the two species [ 17 ]. Thus Cercospora fungi must have unique mechanisms not common to photosynthetic organisms.…”

Section: Introductionmentioning

confidence: 99%

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Characterization of Cercospora nicotianae Hypothetical Proteins in Cercosporin Resistance

2015

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The photoactivated toxin, cercosporin, produced by Cercospora species, plays an important role in pathogenesis of this fungus to host plants. Cercosporin has almost universal toxicity to cells due to its production of reactive oxygen species including singlet oxygen. For that reason, Cercospora species, which are highly resistant to their own toxin, are good candidates to identify genes for resistance to cercosporin and to the reactive oxygen species it produces. In previous research, the zinc cluster transcription factor CRG1 (cercosporin resistance gene 1) was found to be crucial for Cercospora species’ resistance against cercosporin, and subtractive hybridization analysis identified 185 genes differentially expressed between Cercospora nicotianae wild type (wt) and a crg1 mutant. The focus of this work was to identify and characterize the hypothetical proteins that were identified in the Cercospora nicotianae subtractive library as potential resistance factors. Quantitative RT-PCR analysis of the 20 genes encoding hypothetical proteins showed that two, 24cF and 71cR, were induced under conditions of cercosporin toxicity, suggesting a role in resistance. Transformation and expression of 24cF and 71cR in the cercosporin-sensitive fungus, Neurospora crassa, showed that 71cR provided increased resistance to cercosporin toxicity, whereas no significant increase was observed in 24cF transformants. Gene disruption was used to generate C. nicotianae 71cR mutants; these mutants did not differ from wt C. nicotianae in cercosporin resistance or production. Quantitative RT-PCR analysis showed induction of other resistance genes in the 71cR mutant that may compensate for the loss of 71cR. Analysis of 71cR conserved domains and secondary and tertiary structure identify the protein as having an NTF2-like superfamily DUF1348 domain with unknown function, to be intracellular and localized in the cytosol, and to have similarities to proteins in the steroid delta-isomerase family.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of Cercospora nicotianae Hypothetical Proteins in Cercosporin Resistance

2015

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Membrane transporters in self resistance of Cercospora nicotianae to the photoactivated toxin cercosporin

et al. 2015

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The goal of this work is to characterize membrane transporter genes in Cercospora fungi required for autoresistance to the photoactivated, active-oxygen-generating toxin cercosporin they produce for infection of host plants. Previous studies implicated a role for diverse membrane transporters in cercosporin resistance. In this study, transporters identified in a subtractive cDNA library between a Cercospora nicotianae wild type and a cercosporin-sensitive mutant were characterized, including two ABC transporters (CnATR2, CnATR3), an MFS transporter (CnMFS2), a uracil transporter, and a zinc transport protein. Phylogenetic analysis showed that only CnATR3 clustered with transporters previously characterized to be involved in cercosporin resistance. Quantitative RT-PCR analysis of gene expression under conditions of cercosporin toxicity, however, showed that only CnATR2 was upregulated, thus this gene was selected for further characterization. Transformation and expression of CnATR2 in the cercosporin-sensitive fungus Neurospora crassa significantly increased cercosporin resistance. Targeted gene disruption of CnATR2 in the wild type C. nicotianae, however, did not decrease resistance. Expression analysis of other transporters in the cnatr2 mutant under conditions of cercosporin toxicity showed significant upregulation of the cercosporin facilitator protein gene (CFP), encoding an MFS transporter previously characterized as playing an important role in cercosporin autoresistance in Cercospora species. We conclude that cercosporin autoresistance in Cercospora is mediated by multiple genes, and that the fungus compensates for mutations by up-regulation of other resistance genes. CnATR2 may be a useful gene, alone or in addition to other known resistance genes, for engineering Cercospora resistance in crop plants.

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Singlet Molecular Oxygen Reactions with Nucleic Acids, Lipids, and Proteins

et al. 2019

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Singlet oxygen ( 1 O 2 ) is a biologically relevant reactive oxygen species capable of efficiently reacting with cellular constituents. The resulting oxidatively generated damage to nucleic acids, membrane unsaturated lipids, and protein components has been shown to be implicated in several diseases, including arthritis, cataracts, and skin cancer. Singlet oxygen may be endogenously produced, among various possibilities, by myeloperoxidase, an enzyme implicated in inflammation processes, and also efficiently in skin by the UVA component of solar radiation through photosensitization reactions. Emphasis is placed in this Review on the description of the main oxidation reactions initiated by 1 O 2 and the resulting modifications within key cellular targets, including guanine for nucleic acids, unsaturated lipids, and targeted amino acids. Most of these reactions give rise to peroxides and dioxetanes, whose formation has been rationalized in terms of [4+2] cycloaddition and 1,2-cycloaddition with dienes + olefins, respectively. The use of [ 18 O]-labeled thermolabile endoperoxides as a source of [ 18 O]-labeled 1 O 2 has been applied to study mechanistic aspects and preferential targets of 1 O 2 in biological systems. A relevant major topic deals with the search for the molecular signature of the 1 O 2 formation in targeted biomolecules within cells. It may be anticipated that [ 18 O]-labeled 1 O 2 and labeled peroxides in association with sensitive mass spectrometric methods should constitute powerful tools for this purpose.

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The role of Cercospora zeae-maydis homologs of Rhodobacter sphaeroides1O2-resistance genes in resistance to the photoactivated toxin cercosporin

Cited by 6 publications

References 52 publications

Characterization of Cercospora nicotianae Hypothetical Proteins in Cercosporin Resistance

Characterization of Cercospora nicotianae Hypothetical Proteins in Cercosporin Resistance

Membrane transporters in self resistance of Cercospora nicotianae to the photoactivated toxin cercosporin

Singlet Molecular Oxygen Reactions with Nucleic Acids, Lipids, and Proteins

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