scholarly journals Duplication of a Conditionally Dispensable Chromosome Carrying Pea Pathogenicity (PEP) Gene Clusters in Nectria haematococca

2007 ◽  
Vol 20 (12) ◽  
pp. 1495-1504 ◽  
Author(s):  
Hamid S. Garmaroodi ◽  
Masatoki Taga
Keyword(s):  
Pathogenic Fungi ◽  
Gene Clusters ◽  
Chromosome Counting ◽  
Nectria Haematococca ◽  
Supernumerary Chromosomes ◽  
Dosage Effects ◽  
Dispensable Chromosome ◽  
Multiple Copies ◽  
Fusion Products

A supernumerary chromosome called a conditionally dispensable chromosome (CDC) is essential for pathogenicity of Nectria haematococca on pea. Among several CDCs discovered in N. haematococca, the PDA1 CDC that harbors the pisatin demethylation gene PDA1 is one of the best-studied CDCs and serves as a model for plant-pathogenic fungi. Although the presence of multiple copies is usual for supernumerary chromosomes in other eukaryotes, this possibility has not been examined well for any CDCs in N. haematococca. In this study, we produced strains with multiple copies of the PDA1 CDC by protoplast fusion and analyzed dosage effects of this chromosome. Using multiple methods, including cytological chromosome counting and fluorescence in situ hybridization, the fusion products between two transformants derived from the same strain that bears a single PDA1 CDC were shown to contain two PDA1 CDCs from both transformants and estimated to be haploid resulting from the deletion of an extra set or sets of A chromosomes in the fused nuclei. In phenotype assays, dosage effects of PDA1 CDC in the fusion products were evident as increased virulence and homoserine-utilizing ability compared with the parents. In a separate fusion experiment, PDA1 CDC accumulated up to four copies in a haploid genome.

scholarly journals Maackiain Detoxification Contributes to the Virulence of Nectria haematococca MP VI on Chickpea

1998 ◽  
Vol 11 (4) ◽  
pp. 317-326 ◽  
Author(s):  
Jürg Enkerli ◽  
Garima Bhatt ◽  
Sarah F. Covert
Keyword(s):  
Gene Loss ◽  
Nectria Haematococca ◽  
Toxic Compound ◽  
Chemically Induced ◽  
Dispensable Chromosome ◽  
Mating Population ◽  
Multiple Copies ◽  
Weakly Virulent ◽  
High Level ◽  
Highly Virulent

Nectria haematococca mating population (MP) VI isolates that contain the MAK1 gene are able to degrade maackiain, a chickpea (Cicer arietinum) phytoalexin, to a less toxic compound. To test the contribution of MAK1 to the virulence of N. haematococca MP VI on chickpea, the MAK1 gene was disrupted in a highly virulent Mak+ isolate or added to a weakly virulent Mak- isolate via transformation. The disruption of MAK1 decreased virulence to a moderate level, while addition of multiple copies of MAK1 increased virulence to either a moderate or a high level. These data demonstrate that maackiain detoxification is a determinant, but not the only determinant, of virulence in N. haematococca MP VI isolates capable of causing disease on chickpea. MAK1 is located on a 1.6-Mb conditionally dispensable chromosome. To ascertain if there are additional genes influencing virulence toward chickpea stems on the MAK1 chromosome, the loss of this chromosome was chemically induced in an isolate containing the disrupted MAK1 gene. Loss of the MAK1 chromosome did not reduce virulence toward chickpea stems further, thus indicating that no additional genes for virulence on this part of the host plant are located on the MAK1 chromosome.

scholarly journals Enzymatic Degradation of Phenazines Can Generate Energy and Protect Sensitive Organisms from Toxicity

mBio ◽  
2015 ◽  
Vol 6 (6) ◽  
Author(s):  
Kyle C. Costa ◽  
Megan Bergkessel ◽  
Scott Saunders ◽  
Jonas Korlach ◽  
Dianne K. Newman
Keyword(s):  
Microbial Communities ◽  
Pathogenic Fungi ◽  
Cell Types ◽  
Redox Activity ◽  
Mycobacterium Fortuitum ◽  
Active Metabolites ◽  
Content Type ◽  
Phenazine Production ◽  
Physiological Benefits

ABSTRACTDiverse bacteria, including severalPseudomonasspecies, produce a class of redox-active metabolites called phenazines that impact different cell types in nature and disease. Phenazines can affect microbial communities in both positive and negative ways, where their presence is correlated with decreased species richness and diversity. However, little is known about how the concentration of phenazines is modulatedin situand what this may mean for the fitness of members of the community. Through culturing of phenazine-degrading mycobacteria, genome sequencing, comparative genomics, and molecular analysis, we identified several conserved genes that are important for the degradation of threePseudomonas-derived phenazines: phenazine-1-carboxylic acid (PCA), phenazine-1-carboxamide (PCN), and pyocyanin (PYO). PCA can be used as the sole carbon source for growth by these organisms. Deletion of several genes inMycobacterium fortuitumabolishes the degradation phenotype, and expression of two genes in a heterologous host confers the ability to degrade PCN and PYO. In cocultures with phenazine producers, phenazine degraders alter the abundance of different phenazine types. Not only does degradation support mycobacterial catabolism, but also it provides protection to bacteria that would otherwise be inhibited by the toxicity of PYO. Collectively, these results serve as a reminder that microbial metabolites can be actively modified and degraded and that these turnover processes must be considered when the fate and impact of such compounds in any environment are being assessed.IMPORTANCEPhenazine production byPseudomonasspp. can shape microbial communities in a variety of environments ranging from the cystic fibrosis lung to the rhizosphere of dryland crops. For example, in the rhizosphere, phenazines can protect plants from infection by pathogenic fungi. The redox activity of phenazines underpins their antibiotic activity, as well as providing pseudomonads with important physiological benefits. Our discovery that soil mycobacteria can catabolize phenazines and thereby protect other organisms against phenazine toxicity suggests that phenazine degradation may influence turnoverin situ. The identification of genes involved in the degradation of phenazines opens the door to monitoring turnover in diverse environments, an essential process to consider when one is attempting to understand or control communities influenced by phenazines.

scholarly journals Karyotype Characterization of Nine Periwinkle Species (Gastropoda, Littorinidae)

Genes ◽  
2018 ◽  
Vol 9 (11) ◽  
pp. 517 ◽  
Author(s):  
Daniel García-Souto ◽  
Sandra Alonso-Rubido ◽  
Diana Costa ◽  
José Eirín-López ◽  
Emilio Rolán-Álvarez ◽  
...  
Keyword(s):  
Dna Sequences ◽  
Chromosome Numbers ◽  
Gene Clusters ◽  
Chromosomal Mapping ◽  
Closely Related Species ◽  
Submetacentric Chromosome ◽  
The Family ◽  
Littorina Arcana

Periwinkles of the family Littorinidae (Children, 1834) are common members of seashore littoral communities worldwide. Although the family is composed of more than 200 species belonging to 18 genera, chromosome numbers have been described in only eleven of them. A molecular cytogenetic analysis of nine periwinkle species, the rough periwinkles Littorina arcana, L. saxatilis, and L. compressa, the flat periwinkles L. obtusata and L. fabalis, the common periwinkle L. littorea, the mangrove periwinkle Littoraria angulifera, the beaded periwinkle Cenchritis muricatus, and the small periwinkle Melarhaphe neritoides was performed. All species showed diploid chromosome numbers of 2n = 34, and karyotypes were mostly composed of metacentric and submetacentric chromosome pairs. None of the periwinkle species showed chromosomal differences between male and female specimens. The chromosomal mapping of major and minor rDNA and H3 histone gene clusters by fluorescent in situ hybridization demonstrated that the patterns of distribution of these DNA sequences were conserved among closely related species and differed among less related ones. All signals occupied separated loci on different chromosome pairs without any evidence of co-localization in any of the species.

scholarly journals A Novel Automethylation Reaction in the Aspergillus nidulans LaeA Protein Generates S-Methylmethionine

2013 ◽  
Vol 288 (20) ◽  
pp. 14032-14045 ◽  
Author(s):  
Alexander N. Patananan ◽  
Jonathan M. Palmer ◽  
Graeme S. Garvey ◽  
Nancy P. Keller ◽  
Steven G. Clarke
Keyword(s):  
Amino Acid ◽  
Aspergillus Nidulans ◽  
Point Mutations ◽  
Pathogenic Fungi ◽  
Gene Clusters ◽  
Methionine Residue ◽  
Cell Extracts ◽  
Animal Pathogens

The filamentous fungi in the genus Aspergillus are opportunistic plant and animal pathogens that can adapt to their environment by producing various secondary metabolites, including lovastatin, penicillin, and aflatoxin. The synthesis of these small molecules is dependent on gene clusters that are globally regulated by the LaeA protein. Null mutants of LaeA in all pathogenic fungi examined to date show decreased virulence coupled with reduced secondary metabolism. Although the amino acid sequence of LaeA contains the motifs characteristic of seven-β-strand methyltransferases, a methyl-accepting substrate of LaeA has not been identified. In this work we did not find a methyl-accepting substrate in Aspergillus nidulans with various assays, including in vivo S-adenosyl-[methyl-3H]methionine labeling, targeted in vitro methylation experiments using putative protein substrates, or in vitro methylation assays using whole cell extracts grown under different conditions. However, in each experiment LaeA was shown to self-methylate. Amino acid hydrolysis of radioactively labeled LaeA followed by cation exchange and reverse phase chromatography identified methionine as the modified residue. Point mutations show that the major site of modification of LaeA is on methionine 207. However, in vivo complementation showed that methionine 207 is not required for the biological function of LaeA. LaeA is the first protein to exhibit automethylation at a methionine residue. These findings not only indicate LaeA may perform novel chemistry with S-adenosylmethionine but also provide new insights into the physiological function of LaeA.

scholarly journals Unusual and Highly Bioactive Sesterterpenes Synthesized by Pleurotus ostreatus during Coculture with Trametes robiniophila Murr

2019 ◽  
Vol 85 (14) ◽  
Author(s):  
Xiao-Ting Shen ◽  
Xu-Hua Mo ◽  
Li-Ping Zhu ◽  
Ling-Ling Tan ◽  
Feng-Yu Du ◽  
...  
Keyword(s):  
Network Analysis ◽  
Secondary Metabolites ◽  
Pleurotus Ostreatus ◽  
Pathogenic Fungi ◽  
Gene Clusters ◽  
Molecular Network ◽  
Terpene Synthase ◽  
High Morbidity ◽  
Content Type ◽  
Trametes Robiniophila

ABSTRACT Candida albicans and Cryptococcus neoformans, human-pathogenic fungi found worldwide, are receiving increasing attention due to high morbidity and mortality in immunocompromised patients. In the present work, 110 fungus pairs were constructed by coculturing 16 wood-decaying basidiomycetes, among which coculture of Trametes robiniophila Murr and Pleurotus ostreatus was found to strongly inhibit pathogenic fungi through bioactivity-guided assays. A combination of metabolomics and molecular network analysis revealed that 44 features were either newly synthesized or produced at high levels in this coculture system and that 6 of the features that belonged to a family of novel and unusual linear sesterterpenes contributed to high activity with MICs of 1 to 32 μg/ml against pathogenic fungi. Furthermore, dynamic 13C-labeling analysis revealed an association between induced features and the corresponding fungi. Unusual sesterterpenes were 13C labeled only in P. ostreatus in a time course after stimulation by the coculture, suggesting that these sesterterpenes were synthesized by P. ostreatus instead of T. robiniophila Murr. Sesterterpene compounds 1 to 3 were renamed postrediene A to C. Real-time reverse transcription-quantitative PCR (RT-qPCR) analysis revealed that transcriptional levels of three genes encoding terpene synthase, farnesyl-diphosphate farnesyltransferase, and oxidase were found to be 8.2-fold, 88.7-fold, and 21.6-fold higher, respectively, in the coculture than in the monoculture, indicating that biosynthetic gene cluster 10 was most likely responsible for the synthesis of these sesterterpenes. A putative biosynthetic pathway of postrediene A to postrediene C was then proposed based on structures of sesterterpenes and molecular network analysis. IMPORTANCE A number of gene clusters involved in biosynthesis of secondary metabolites are presumably silent or expressed at low levels under conditions of standard laboratory cultivation, resulting in a large gap between the pool of discovered metabolites and genome capability. This work mimicked naturally occurring competition by construction of an artificial coculture of basidiomycete fungi for the identification of secondary metabolites with novel scaffolds and excellent bioactivity. Unusual linear sesterterpenes of postrediene A to C synthesized by P. ostreatus not only were promising lead drugs against human-pathogenic fungi but also highlighted a distinct pathway for sesterterpene biosynthesis in basidiomycetes. The current work provides an important basis for uncovering novel gene functions involved in sesterterpene synthesis and for gaining insights into the mechanism of silent gene activation in fungal defense.

scholarly journals Molecular Characterization of Potential Nitrogen Fixation by Anaerobic Methane-Oxidizing Archaea in the Methane Seep Sediments at the Number 8 Kumano Knoll in the Kumano Basin, Offshore of Japan

2009 ◽  
Vol 75 (22) ◽  
pp. 7153-7162 ◽  
Author(s):  
Junichi Miyazaki ◽  
Ryosaku Higa ◽  
Tomohiro Toki ◽  
Juichiro Ashi ◽  
Urumu Tsunogai ◽  
...  
Keyword(s):  
Nitrogen Fixation ◽  
16S Rrna ◽  
16S Rrna Gene ◽  
Gene Clusters ◽  
Rrna Gene ◽  
Methane Seep ◽  
Core Sediments ◽  
The Core ◽  
Group 2

ABSTRACT The potential for microbial nitrogen fixation in the anoxic methane seep sediments in a mud volcano, the number 8 Kumano Knoll, was characterized by molecular phylogenetic analyses. A total of 111 of the nifH (a gene coding a nitrogen fixation enzyme, Fe protein) clones were obtained from different depths of the core sediments, and the phylogenetic analysis of the clones indicated the genetic diversity of nifH genes. The predominant group detected (methane seep group 2), representing 74% of clonal abundance, was phylogenetically related to the nifH sequences obtained from the Methanosarcina species but was most closely related to the nifH sequences potentially derived from the anoxic methanotrophic archaea (ANME-2 archaea). The recovery of the nif gene clusters including the nifH sequences of the methane seep group 2 and the subsequent reverse transcription-PCR detection of the nifD and nifH genes strongly suggested that the genetic components of the gene clusters would be operative for the in situ assimilation of molecular nitrogen (N2) by the host microorganisms. DNA-based quantitative PCR of the archaeal 16S rRNA gene, the group-specific mcrA (a gene encoding the methyl-coenzyme M reductase α subunit) gene, and the nifD and nifH genes demonstrated the similar distribution patterns of the archaeal 16S rRNA gene, the mcrA groups c-d and e, and the nifD and nifH genes through the core sediments. These results supported the idea that the anoxic methanotrophic archaea ANME-2c could be the microorganisms hosting the nif gene clusters and could play an important role in not only the in situ carbon (methane) cycle but also the nitrogen cycle in subseafloor sediments.

scholarly journals Deacetylation of Fungal Exopolysaccharide Mediates Adhesion and Biofilm Formation

mBio ◽  
2016 ◽  
Vol 7 (2) ◽  
Author(s):  
Mark J. Lee ◽  
Alexander M. Geller ◽  
Natalie C. Bamford ◽  
Hong Liu ◽  
Fabrice N. Gravelat ◽  
...  
Keyword(s):  
Biofilm Formation ◽  
Fungal Pathogens ◽  
Molecular Mechanisms ◽  
Pathogenic Fungi ◽  
Gene Clusters ◽  
Biosynthetic Gene Cluster ◽  
Bacterial Biofilm ◽  
Invasive Infection ◽  
Biosynthetic Gene ◽  
Adhesive Properties

ABSTRACTThe moldAspergillus fumigatuscauses invasive infection in immunocompromised patients. Recently, galactosaminogalactan (GAG), an exopolysaccharide composed of galactose andN-acetylgalactosamine (GalNAc), was identified as a virulence factor required for biofilm formation. The molecular mechanisms underlying GAG biosynthesis and GAG-mediated biofilm formation were unknown. We identified a cluster of five coregulated genes that were dysregulated in GAG-deficient mutants and whose gene products share functional similarity with proteins that mediate the synthesis of the bacterial biofilm exopolysaccharide poly-(β1-6)-N-acetyl-d-glucosamine (PNAG). Bioinformatic analyses suggested that the GAG cluster geneagd3encodes a protein containing a deacetylase domain. Because deacetylation ofN-acetylglucosamine residues is critical for the function of PNAG, we investigated the role of GAG deacetylation in fungal biofilm formation. Agd3 was found to mediate deacetylation of GalNAc residues within GAG and render the polysaccharide polycationic. As with PNAG, deacetylation is required for the adherence of GAG to hyphae and for biofilm formation. Growth of the Δagd3mutant in the presence of culture supernatants of the GAG-deficient Δuge3mutant rescued the biofilm defect of the Δagd3mutant and restored the adhesive properties of GAG, suggesting that deacetylation is an extracellular process. The GAG biosynthetic gene cluster is present in the genomes of members of thePezizomycotinasubphylum of theAscomycotaincluding a number of plant-pathogenic fungi and a single basidiomycete species,Trichosporon asahii, likely a result of recent horizontal gene transfer. The current study demonstrates that the production of cationic, deacetylated exopolysaccharides is a strategy used by both fungi and bacteria for biofilm formation.IMPORTANCEThis study sheds light on the biosynthetic pathways governing the synthesis of galactosaminogalactan (GAG), which plays a key role inA. fumigatusvirulence and biofilm formation. We find that bacteria and fungi use similar strategies to synthesize adhesive biofilm exopolysaccharides. The presence of orthologs of the GAG biosynthetic gene clusters in multiple fungi suggests that this exopolysaccharide may also be important in the virulence of other fungal pathogens. Further, these studies establish a molecular mechanism of adhesion in which GAG interacts via charge-charge interactions to bind to both fungal hyphae and other substrates. Finally, the importance of deacetylation in the synthesis of functional GAG and the extracellular localization of this process suggest that inhibition of deacetylation may be an attractive target for the development of novel antifungal therapies.

scholarly journals Synthesis, Structural Investigation and Antimicrobial Properties of Macrocyclic Zinc(II) Complexes with N2O2-Donor Schiff Bases Incorporating 1,2,4-Triazole Ring

2020 ◽  
Vol 32 (12) ◽  
pp. 3151-3156
Keyword(s):  
Schiff Bases ◽  
Structural Investigation ◽  
Thermal Studies ◽  
Antimicrobial Properties ◽  
Triazole Ring ◽  
Pathogenic Fungi ◽  
Elemental Analyses ◽  
Coordinated Water ◽  
In Situ Reactions

A novel series of nano-sized zinc(II) complexes of type [{Zn(M)(H2O)2}(CH3COO–)2] (where M = macrocyclic ligands) has been synthesized by the in situ reactions of Schiff bases derived from 3-(phenyl/substituted phenyl)-4-amino-5-hydrazino-1,2,4-triazoles, salicyldehyde/2-hydroxy-1- naphthaldehyde and 1,4-dibromobutane/1,5-dibromopentane in presence of zinc(II) acetate dihydrate in absolute ethanol. The structures of all these zinc(II) complexes were established on the basis of elemental analyses and spectral data (IR, 1H NMR and 13C NMR). Scanning electron microscopy studies have been carried out to investigate the particle size and surface morphology of a particular complex while thermal studies confirm the presence of coordinated water molecules in all the zinc(II) complexes. The antimicrobial effects of all the synthesized complexes were studied against different species of pathogenic fungi and bacteria.

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