scholarly journals A Complex Ergovaline Gene Cluster in Epichloë Endophytes of Grasses

2007 ◽  
Vol 73 (8) ◽  
pp. 2571-2579 ◽  
Author(s):  
Damien J. Fleetwood ◽  
Barry Scott ◽  
Geoffrey A. Lane ◽  
Aiko Tanaka ◽  
Richard D. Johnson

ABSTRACT Clavicipitaceous fungal endophytes of the genera Epichloë and Neotyphodium form symbioses with grasses of the subfamily Pooideae, in which they can synthesize an array of bioprotective alkaloids. Some strains produce the ergopeptine alkaloid ergovaline, which is implicated in livestock toxicoses caused by ingestion of endophyte-infected grasses. Cloning and analysis of a nonribosomal peptide synthetase (NRPS) gene from Neotyphodium lolii revealed a putative gene cluster for ergovaline biosynthesis containing a single-module NRPS gene, lpsB, and other genes orthologous to genes in the ergopeptine gene cluster of Claviceps purpurea and the clavine cluster of Aspergillus fumigatus. Despite conservation of gene sequence, gene order is substantially different between the N. lolii, C. purpurea, and A. fumigatus ergot alkaloid gene clusters. Southern analysis indicated that the N. lolii cluster was linked with previously identified ergovaline biosynthetic genes dmaW and lpsA. The ergovaline genes are closely associated with transposon relics, including retrotransposons and autonomous and nonautonomous DNA transposons. All genes in the cluster were highly expressed in planta, but expression was very low or undetectable in mycelia from axenic culture. This work provides a genetic foundation for elucidating biochemical steps in the ergovaline pathway, the ecological role of individual ergot alkaloid compounds, and the regulation of their synthesis in planta.

2007 ◽  
Vol 13 ◽  
pp. 491-493
Author(s):  
H. Harzer ◽  
R.D. Johnson ◽  
S. Rasmussen ◽  
C.R. Voisey ◽  
L.J. Johnson

Symbiotic grass associations with fungal endophytes (genera Neotyphodium and Epichloë) display enhanced fitness as well as prolonged field persistence over their endophyte free equivalents. Perennial ryegrass, an important agronomic grass, is typically associated with the N. lolii endophyte. The endophyte lives within the intercellular spaces without inducing any symptoms in the plant. The aim of this study is to elucidate the biosynthetic function of fungal secondary metabolite gene clusters. Non-ribosomal peptide synthetase genes (NRPSs) of unknown function were targeted, as these genes are commonly associated with the production of bioactive peptides some of which are ecologically important. Some novel endophyte NRPS genes have been identified using a degenerate PCR screen; one of these, NRPS5 will be discussed here. Clones were obtained by screening a fosmid Epichloë festucae genomic DNA library and we are currently determining gene function by using targeted gene replacement followed by an assessment in vitro and in planta using metabolomics and appropriate bioassay screens. Keywords: endophyte, NRPS, secondary metabolism


2016 ◽  
Vol 4 (5) ◽  
Author(s):  
Hisayuki Komaki ◽  
Akira Hosoyama ◽  
Natsuko Ichikawa ◽  
Yasuhiro Igarashi

Here, we report the draft genome sequence of Bacillus subtilis TP-B0611, which produces the isocoumarin-type compounds bacilosarcin and amicoumacin. The genome encodes three nonribosomal peptide synthetase (NRPS) gene clusters and one hybrid polyketide synthase (PKS)/NRPS gene cluster. The hybrid PKS/NRPS gene cluster was identified to be responsible for the biosynthesis of bacilosarcins and amicoumacins.


Genes ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 328 ◽  
Author(s):  
Mohammad Sayari ◽  
Magriet A. van der Nest ◽  
Emma T. Steenkamp ◽  
Nicole C. Soal ◽  
P. Markus Wilken ◽  
...  

In filamentous fungi, genes in secondary metabolite biosynthetic pathways are generally clustered. In the case of those pathways involved in nonribosomal peptide production, a nonribosomal peptide synthetase (NRPS) gene is commonly found as a main element of the cluster. Large multifunctional enzymes are encoded by members of this gene family that produce a broad spectrum of bioactive compounds. In this research, we applied genome-based identification of nonribosomal peptide biosynthetic gene clusters in the family Ceratocystidaceae. For this purpose, we used the whole genome sequences of species from the genera Ceratocystis, Davidsoniella, Thielaviopsis, Endoconidiophora, Bretziella, Huntiella, and Ambrosiella. To identify and characterize the clusters, different bioinformatics and phylogenetic approaches, as well as PCR-based methods were used. In all genomes studied, two highly conserved NRPS genes (one monomodular and one multimodular) were identified and their potential products were predicted to be siderophores. Expression analysis of two Huntiella species (H. moniliformis and H. omanensis) confirmed the accuracy of the annotations and proved that the genes in both clusters are expressed. Furthermore, a phylogenetic analysis showed that both NRPS genes of the Ceratocystidaceae formed distinct and well supported clades in their respective phylograms, where they grouped with other known NRPSs involved in siderophore production. Overall, these findings improve our understanding of the diversity and evolution of NRPS biosynthetic pathways in the family Ceratocystidaceae.


Life ◽  
2020 ◽  
Vol 10 (11) ◽  
pp. 257
Author(s):  
Hisayuki Komaki ◽  
Tomohiko Tamura

(1) Background: Phytohabitans is a recently established genus belonging to rare actinomycetes. It has been unclear if its members have the capacity to synthesize diverse secondary metabolites. Polyketide and nonribosomal peptide compounds are major secondary metabolites in actinomycetes and expected as a potential source for novel pharmaceuticals. (2) Methods: Whole genomes of Phytohabitans flavus NBRC 107702T, Phytohabitans rumicis NBRC 108638T, Phytohabitans houttuyneae NBRC 108639T, and Phytohabitans suffuscus NBRC 105367T were sequenced by PacBio. Polyketide synthase (PKS) and nonribosomal peptide synthetase (NRPS) gene clusters were bioinformatically analyzed in the genome sequences. (3) Results: These four strains harbored 10, 14, 18 and 14 PKS and NRPS gene clusters, respectively. Most of the gene clusters were annotated to synthesis unknown chemistries. (4) Conclusions: Members of the genus Phytohabitans are a possible source for novel and diverse polyketides and nonribosomal peptides.


2005 ◽  
Vol 49 (11) ◽  
pp. 4598-4607 ◽  
Author(s):  
Dirk Schwartz ◽  
Nicolas Grammel ◽  
Eva Heinzelmann ◽  
Ullrich Keller ◽  
Wolfgang Wohlleben

ABSTRACT The tripeptide backbone of phosphinothricin (PT) tripeptide (PTT), a compound with herbicidal activity from Streptomyces viridochromogenes, is assembled by three stand-alone peptide synthetase modules. The enzyme PhsA (66 kDa) recruits the PT-precursor N-acetyl-demethylphosphinothricin (N-Ac-DMPT), whereas the two alanine residues of PTT are assembled by the enzymes PhsB and PhsC (129 and 119 kDa, respectively). During or after assembly, the N-Ac-DMPT residue in the peptide is converted to PT by methylation and deacetylation. Both phsB and phsC appear to be cotranscribed together with two other genes from a single promoter and they are located at a distance of 20 kb from the gene phsA, encoding PhsA, in the PTT biosynthesis gene cluster of S. viridochromogenes. PhsB and PhsC represent single nonribosomal peptide synthetase elongation modules lacking a thioesterase domain. Gene inactivations, genetic complementations, determinations of substrate specificity of the heterologously produced proteins, and comparison of PhsC sequence with the amino terminus of the alanine-activating nonribosomal peptide synthetase PTTSII from S. viridochromogenes confirmed the role of the two genes in the bialanylation of Ac-DMPT. The lack of an integral thioesterase domain in the PTT assembly system points to product release possibly involving two type II thioesterase genes (the1 and the2) located in the PTT gene cluster alone or in conjunction with an as yet unknown mechanism of product release.


Author(s):  
Aileen Bayot Custodio ◽  
Edwin Plata Alcantara

A phage P1-derived artificial chromosome (PAC) library was constructed from genomic DNA of Streptomyces sp. PCS3-D2. Polymerase chain reaction (PCR) screening of the PAC library revealed two clones, PAC16D and P222O, which were positively identified to harbor polyketide synthase (PKS) Type I and PKS Type III gene clusters, respectively. Restriction enzyme digestion showed that PAC16D and PAC222O contained a 130 kb and a 140 kb insert, respectively. Results of sequencing and bioinformatics analyses revealed that PAC16D comprised of a full-length PKS type I bafilomycin gene cluster while PAC222O harbored truncated siderophore and putative gene clusters as well as a complete PKS III biosynthetic gene cluster. The PKS III gene cluster had three genes similar to alkyl resorcinol biosynthetic genes, however majority of the novel gene cluster had little similarity to known PKS Type III gene clusters. The successful cloning and identification of these gene clusters from Streptomyces sp. PCS3-D2 serve as the jump off point to further genetic manipulation in order to produce the insecticidal natural product in a heterologous host.


Marine Drugs ◽  
2019 ◽  
Vol 17 (7) ◽  
pp. 388 ◽  
Author(s):  
Li Liao ◽  
Shiyuan Su ◽  
Bin Zhao ◽  
Chengqi Fan ◽  
Jin Zhang ◽  
...  

Rare actinobacterial species are considered as potential resources of new natural products. Marisediminicola antarctica ZS314T is the only type strain of the novel actinobacterial genus Marisediminicola isolated from intertidal sediments in East Antarctica. The strain ZS314T was able to produce reddish orange pigments at low temperatures, showing characteristics of carotenoids. To understand the biosynthetic potential of this strain, the genome was completely sequenced for data mining. The complete genome had 3,352,609 base pairs (bp), much smaller than most genomes of actinomycetes. Five biosynthetic gene clusters (BGCs) were predicted in the genome, including a gene cluster responsible for the biosynthesis of C50 carotenoid, and four additional BGCs of unknown oligosaccharide, salinixanthin, alkylresorcinol derivatives, and NRPS (non-ribosomal peptide synthetase) or amino acid-derived compounds. Further experimental characterization indicated that the strain may produce C.p.450-like carotenoids, supporting the genomic data analysis. A new xanthorhodopsin gene was discovered along with the analysis of the salinixanthin biosynthetic gene cluster. Since little is known about this genus, this work improves our understanding of its biosynthetic potential and provides opportunities for further investigation of natural products and strategies for adaptation to the extreme Antarctic environment.


2017 ◽  
Vol 83 (15) ◽  
Author(s):  
Robert J. Dorosky ◽  
Jun Myoung Yu ◽  
Leland S. Pierson ◽  
Elizabeth A. Pierson

ABSTRACT R-type tailocins are high-molecular-weight bacteriocins that resemble bacteriophage tails and are encoded within the genomes of many Pseudomonas species. In this study, analysis of the P. chlororaphis 30-84 R-tailocin gene cluster revealed that it contains the structural components to produce two R-tailocins of different ancestral origins. Two distinct R-tailocin populations differing in length were observed in UV-induced lysates of P. chlororaphis 30-84 via transmission electron microscopy. Mutants defective in the production of one or both R-tailocins demonstrated that the killing spectrum of each tailocin is limited to Pseudomonas species. The spectra of pseudomonads killed by the two R-tailocins differed, although a few Pseudomonas species were either killed by or insusceptible to both tailocins. Tailocin release was disrupted by deletion of the holin gene within the tailocin gene cluster, demonstrating that the lysis cassette is required for the release of both R-tailocins. The loss of functional tailocin production reduced the ability of P. chlororaphis 30-84 to compete with an R-tailocin-sensitive strain within biofilms and rhizosphere communities. Our study demonstrates that Pseudomonas species can produce more than one functional R-tailocin particle sharing the same lysis cassette but differing in their killing spectra. This study provides evidence for the role of R-tailocins as determinants of bacterial competition among plant-associated Pseudomonas in biofilms and the rhizosphere. IMPORTANCE Recent studies have identified R-tailocin gene clusters potentially encoding more than one R-tailocin within the genomes of plant-associated Pseudomonas but have not demonstrated that more than one particle is produced or the ecological significance of the production of multiple R-tailocins. This study demonstrates for the first time that Pseudomonas strains can produce two distinct R-tailocins with different killing spectra, both of which contribute to bacterial competition between rhizosphere-associated bacteria. These results provide new insight into the previously uncharacterized role of R-tailocin production by plant-associated Pseudomonas species in bacterial population dynamics within surface-attached biofilms and on roots.


2001 ◽  
Vol 14 (12) ◽  
pp. 1426-1435 ◽  
Author(s):  
Brenda K. Scholz-Schroeder ◽  
Jonathan D. Soule ◽  
Shi-En Lu ◽  
Ingeborg Grgurina ◽  
Dennis C. Gross

Genetic and phenotypic mapping of an approximately 145-kb DraI fragment of Pseudomonas syringae pv. syringae strain B301D determined that the syringomycin (syr) and syringopeptin (syp) gene clusters are localized to this fragment. The syr and syp gene clusters encompass approximately 55 kb and approximately 80 kb, respectively. Both phytotoxins are synthesized by a thiotemplate mechanism of biosynthesis, requiring large multienzymatic proteins called peptide synthetases. Genes encoding peptide synthetases were identified within the syr and syp gene clusters, accounting for 90% of the DraI fragment. In addition, genes encoding regulatory and secretion proteins were localized to the DraI fragment. In particular, the salA gene, encoding a regulatory element responsible for syringomycin production and lesion formation in P. syringae pv. syringae strain B728a, was localized to the syr gene cluster. A putative ATP-binding cassette (ABC) transporter homolog was determined to be physically located in the syp gene cluster, but phenotypically affects production of both phytotoxins. Preliminary size estimates of the syr and syp gene clusters indicate that they represent two of the largest nonribosomal peptide synthetase gene clusters. Together, the syr and syp gene clusters encompass approximately 135 kb of DNA and may represent a genomic island in P. syringae pv. syringae that contributes to virulence in plant hosts.


2007 ◽  
Vol 189 (23) ◽  
pp. 8528-8536 ◽  
Author(s):  
Céline Plainvert ◽  
Philippe Bidet ◽  
Chantal Peigne ◽  
Valérie Barbe ◽  
Claudine Médigue ◽  
...  

ABSTRACT A new highly pathogenic clone of Escherichia coli meningitis strains harboring the unusual serogroup O45 has recently emerged in France. To gain insight into the pathogenicity of this new clone, we investigated the possible role of antigen O45 in the virulence of strain S88 (O45:K1:H7), representative of this emerging clone. We first showed that the S88 O-antigen gene cluster sequence differs from that of O45 in the reference strain E. coli 96-3285, suggesting that the two O45 polysaccharides, while probably sharing a community of epitopes, represent two different antigens. The unique functional organization of the two O-antigen gene clusters and the low DNA sequence homology of the orthologous genes suggest that the two loci originated from a common ancestor and have since undergone multiple recombination events. Phylogenetic analysis based on the flanking gene gnd sequences indicates that the S88 antigen O45 (O45S88) gene cluster may have been acquired, at least in part, from another member of the Enterobacteriaceae. Mutagenesis of the O45S88 antigen gene cluster was used for functional analysis of the loci and revealed the crucial role of the O polysaccharide in S88 virulence in a neonatal rat meningitis model. We also developed a PCR method to specifically identify the O45S88 antigen gene cluster. Together, our findings suggest that horizontal acquisition of a new O-antigen gene cluster, at least partly from another species, may have been a key event in the emergence and virulence of the E. coli O45:K1:H7 clone in France.


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