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Microbiology Resource Announcements Aug 2018Here, we present the draft genome sequence of Pseudomonas protegens strain BNJ-SS-45, which was isolated from wheat rhizosphere. The genome is assembled with...
Here, we present the draft genome sequence of Pseudomonas protegens strain BNJ-SS-45, which was isolated from wheat rhizosphere. The genome is assembled with 7,116,445 bp with a GC content of 63.34% consisting of 32 scaffolds. The genome is useful in prediction of secondary metabolites, particularly rhizoxin, pyoverdine, and bacteriocin.
PubMed: 30533914
DOI: 10.1128/MRA.00926-18 -
Antimicrobial Agents and Chemotherapy May 2004The microtubule, which is one of the major targets of anthelmintics, anticancer drugs, and fungicides, is composed mainly of alpha- and beta-tubulins. We focused on a...
Screening for microtubule-disrupting antifungal agents by using a mitotic-arrest mutant of Aspergillus nidulans and novel action of phenylalanine derivatives accompanying tubulin loss.
The microtubule, which is one of the major targets of anthelmintics, anticancer drugs, and fungicides, is composed mainly of alpha- and beta-tubulins. We focused on a unique characteristic of an Aspergillus nidulans benA33 mutant to screen for microtubule-disrupting antifungal agents. This mutant, which has a beta-tubulin with a mutation of a single amino acid, undergoes mitotic arrest due to the formation of hyperstable microtubules at 37 degrees C. The heat sensitivity of the mutant is remedied by some antimicrotubule agents. We found that an agar plate assay with the mutant was able to distinguish three types of microtubule inhibitors. The growth recovery zones of the mutant were formed around paper disks containing microtubule inhibitors, including four benzimidazoles, ansamitocin P-3, griseofulvin, and rhizoxin, on the agar plate at 37 degrees C. Nocodazole, thiabendazole, and griseofulvin reversed the mitotic arrest of the mutant and promoted its hyphal growth. Ansamitocin P-3 and rhizoxin showed growth recovery zones around the growth-inhibitory zones. Benomyl and carbendazim also reversed mitotic arrest but produced weaker growth recovery than the aforementioned drugs. Other microtubule inhibitors, such as colchicine, Colcemid, paclitaxel, podophyllotoxin, TN-16, vinblastine, and vincristine, as well as some cytoskeletal inhibitors tested, did not show such activity. In our screening, we newly identified two mycotoxins, citrinin and patulin, two sesquiterpene dialdehydes, polygodial and warburganal, and four phenylalanine derivatives, arphamenine A, L-2,5-dihydrophenylalanine (DHPA), N-tosyl-L-phenylalanine chloromethylketone, and N-carbobenzoxy-L-phenylalanine chloromethyl ketone. In a wild-type strain of A. nidulans, DHPA caused selective losses of microtubules, as determined by fluorescence microscopy, and of both alpha- and beta-tubulins, as determined by Western blot analysis. This screening method involving the benA33 mutant of A. nidulans is useful, convenient, and highly selective. The phenylalanine derivatives tested are of a novel type of microtubule-disrupting antifungal agents, producing an accompanying loss of tubulins, and are different from well-known tubulin inhibitors affecting the assembly of tubulin dimers into microtubules.
Topics: Adenine; Antifungal Agents; Antineoplastic Agents; Aspergillus nidulans; Blotting, Western; Cell Nucleus; Chromosomes, Fungal; Coloring Agents; Drug Evaluation, Preclinical; Electrophoresis, Polyacrylamide Gel; Fungal Proteins; Fungi; Microbial Sensitivity Tests; Microscopy, Fluorescence; Microtubules; Mitosis; Mitotic Index; Nocodazole; Oxazines; Phenylalanine; Tubulin; Xanthenes
PubMed: 15105129
DOI: 10.1128/AAC.48.5.1739-1748.2004 -
The Journal of Biological Chemistry Oct 1990Dolastatin 10, a potent antimitotic peptide from a marine animal, strongly inhibits microtubule assembly, tubulin-dependent GTP hydrolysis, and the binding of vinca...
Dolastatin 10, a potent antimitotic peptide from a marine animal, strongly inhibits microtubule assembly, tubulin-dependent GTP hydrolysis, and the binding of vinca alkaloids to tubulin. In studies of the binding of [3H]vincristine to the protein, with vinblastine as a control for competitive inhibition (Ki, 6.6 microM), we found that the macrolide antimitotic agents maytansine and rhizoxin were also competitive inhibitors (Ki values, 3.1 and 12 microM). Dolastatin 10 and an unrelated peptide antimitotic, phomopsin A, were more potent but noncompetitive inhibitors (Ki values, 1.4 and 2.8 microM). Since maytansine and, to a much lesser extent, vinblastine interfere with nucleotide exchange on tubulin, all drugs were examined for effects on nucleotide interactions at the exchangeable GTP site. Rhizoxin had effects intermediate between those of vinblastine and maytansine. Both peptides inhibited binding of radiolabeled GTP to tubulin even more strongly than did maytansine, but no drug displaced nucleotide from tubulin. The drugs were evaluated for stabilizing effects on the colchicine binding activity of tubulin. The peptides prevented loss of this activity, and vinblastine provided partial protection, while rhizoxin and maytansine did not stabilize tubulin. A tripeptide segment of dolastatin 10 also effectively inhibits tubulin polymerization and GTP hydrolysis. The tripeptide did not significantly inhibit either vincristine binding or nucleotide exchange, nor did it stabilize colchicine binding. These findings are rationalized in terms of a model with two distinct drug binding sites in close physical proximity to each other and to the exchangeable GTP site on beta-tubulin.
Topics: Animals; Binding Sites; Brain; Cattle; Depsipeptides; Kinetics; Maytansine; Microtubules; Models, Structural; Molecular Structure; Oligopeptides; Structure-Activity Relationship; Tubulin; Vinblastine; Vinca Alkaloids; Vincristine
PubMed: 2211617
DOI: No ID Found -
Japanese Journal of Cancer Research :... Dec 1997Previous studies by our and other groups have shown that microbial products containing more than one epoxide group, including eponemycin, radicicol, depudecin and...
Previous studies by our and other groups have shown that microbial products containing more than one epoxide group, including eponemycin, radicicol, depudecin and AGM-1470, exhibits anti-angio-genic activity in an in vivo assay system involving chorioallantoic membranes (CAMs) of growing chick embryos. Based on these findings, rhizoxin, a microbial metabolite that contains two epoxide groups and exhibits anti-tubulin activity, was tested for anti-angiogenic activity in a CAM assay system. Rhizoxin caused dose-dependent inhibition of embryonic angiogenesis, the ID50 value being 2 ng (3.2 pmol) per egg. In addition, this compound (2 mg/kg i.p.) significantly suppressed neovascularization induced by M5076 mouse tumor cells in a mouse dorsal air sac assay system, compared to the vehicle alone (P < 0.05). These results indicate that rhizoxin is a novel inhibitor of angiogenesis, and that is has potential as a new therapeutic agent for cancer.
Topics: Animals; Antibiotics, Antineoplastic; Chick Embryo; Dose-Response Relationship, Drug; Epoxy Compounds; Lactones; Macrolides; Mice; Neovascularization, Pathologic; Neovascularization, Physiologic; Spinal Neoplasms; Spinal Nerve Roots
PubMed: 9473728
DOI: 10.1111/j.1349-7006.1997.tb00339.x -
EFSA Journal. European Food Safety... Oct 2020The European Commission requested EFSA to provide scientific advice on the translocation potential by MA342 in plants after seed treatment of cereals and peas and, if...
The European Commission requested EFSA to provide scientific advice on the translocation potential by MA342 in plants after seed treatment of cereals and peas and, if applicable, for a revision of the assessment of the risk to humans by its metabolite 2,3-deepoxy-2,3-didehydro-rhizoxin (DDR) and this based on the evidence available in the dossier for renewal of the approval. The information from other strains than MA342 was taken into account with care, because the studies available in the dossier did not confirm the identity of the strain MA342 as belonging to the species . It has been concluded that there is a potential for translocation of MA342 to edible plant parts following seed treatment till an estimated concentration up to about 10 cfu/g and some exposure can be assumed by consumption of fresh commodities. Also, production of the metabolite DDR in the plant cannot be excluded. Regarding levels of DDR in the raw agricultural commodities, exposure estimates based on the limit of quantification (LOQ) for DDR in cereals cannot be further refined while there is no information on the levels of DDR in peas in the dossier. As regards genotoxicity, DDR induced chromosomal damage; however, it was not possible to conclude whether it is through an aneugenic or clastogenic mechanism. Hence, it is not possible to draw a reliable conclusion that DDR is producing an aneugenic effect nor to determine a threshold dose for aneugenicity. Thus, it is not possible to revise the human risk assessment as regards exposure to DDR. The concerns identified in the EFSA conclusion of 2017 remain.
PubMed: 33133274
DOI: 10.2903/j.efsa.2020.6276 -
The Journal of Antibiotics Mar 1986The absolute structure of rhizoxin, a potent antifungal and antitumor antibiotic, was determined by interrelation with compound 2 whose structure was established by...
The absolute structure of rhizoxin, a potent antifungal and antitumor antibiotic, was determined by interrelation with compound 2 whose structure was established by X-ray analysis. Since a 18OH group was introduced at C-3 on a hydrolytic cleavage of C-2, C-3 epoxy group with alkaline H2(18)O, the original epoxy oxygen should be retained at C-2. The stereo-chemistry at C-2 and C-3 positions in rhizoxin was, therefore, determined as 2R,3S.
Topics: Chemical Phenomena; Chemistry; Lactones; Macrolides; Stereoisomerism
PubMed: 3754548
DOI: 10.7164/antibiotics.39.424 -
Microbiology Resource Announcements Feb 2020We report the draft genome sequence of sp. strain LD120, which was isolated from a brown macroalga in the Baltic Sea. The genome of this marine subgroup bacterium...
We report the draft genome sequence of sp. strain LD120, which was isolated from a brown macroalga in the Baltic Sea. The genome of this marine subgroup bacterium harbors biosynthetic gene clusters for toxic metabolites typically produced by members of this subgroup, including 2,4-diacetylphloroglucinol, pyoluteorin, and rhizoxin analogs.
PubMed: 32079630
DOI: 10.1128/MRA.01305-19 -
Plant Physiology Jun 2013In Arabidopsis (Arabidopsis thaliana), malate released into the rhizosphere has various roles, such as detoxifying rhizotoxic aluminum (Al) and recruiting beneficial...
In Arabidopsis (Arabidopsis thaliana), malate released into the rhizosphere has various roles, such as detoxifying rhizotoxic aluminum (Al) and recruiting beneficial rhizobacteria that induce plant immunity. ALUMINUM-ACTIVATED MALATE TRANSPORTER1 (AtALMT1) is a critical gene in these responses, but its regulatory mechanisms remain unclear. To explore the mechanism of the multiple responses of AtALMT1, we profiled its expression patterns in wild-type plants, in transgenic plants harboring various deleted promoter constructs, and in mutant plants with defects in signal transduction in response to various inducers. AtALMT1 transcription was clearly induced by indole-3-acetic acid (IAA), abscisic acid (ABA), low pH, and hydrogen peroxide, indicating that it was able to respond to multiple signals, while it was not induced by methyl jasmonate and salicylic acid. The IAA-signaling double mutant nonphototropic hypocotyls4-1; auxin-responsive factor19-1 and the ABA-signaling mutant aba insensitive1-1 did not respond to auxin and ABA, respectively, but both showed an Al response comparable to that of the wild type. A synthetic microbe-associated molecular pattern peptide, flagellin22 (flg22), induced AtALMT1 transcription but did not induce the transcription of IAA- and ABA-responsive biomarker genes, indicating that both Al and flg22 responses of AtALMT1 were independent of IAA and ABA signaling. An in planta β-glucuronidase reporter assay identified that the ABA response was regulated by a region upstream (-317 bp) from the first ATG codon, but other stress responses may share critical regulatory element(s) located between -292 and -317 bp. These results illustrate the complex regulation of AtALMT1 expression during the adaptation to abiotic and biotic stresses.
Topics: ATP-Binding Cassette Transporters; Abscisic Acid; Acetates; Adaptation, Physiological; Arabidopsis; Arabidopsis Proteins; Cyclopentanes; Gene Expression Regulation, Plant; Hydrogen Peroxide; Indoleacetic Acids; Macrolides; Mutation; Organic Anion Transporters; Oxylipins; Plant Growth Regulators; Plant Roots; Plants, Genetically Modified; Promoter Regions, Genetic; Regulatory Sequences, Nucleic Acid; Salicylic Acid; Signal Transduction
PubMed: 23624855
DOI: 10.1104/pp.113.218065 -
Annals of Oncology : Official Journal... Nov 1992
Clinical Trial
Topics: Animals; Antibiotics, Antineoplastic; Drug Evaluation; Drug Resistance; Humans; Lactones; Macrolides; Neoplasms, Experimental
PubMed: 1450059
DOI: 10.1093/oxfordjournals.annonc.a058321 -
PloS One 2014The biocontrol strain Pseudomonas sp. Cab57 was isolated from the rhizosphere of shepherd's purse growing in a field in Hokkaido by screening the antibiotic producers....
The biocontrol strain Pseudomonas sp. Cab57 was isolated from the rhizosphere of shepherd's purse growing in a field in Hokkaido by screening the antibiotic producers. The whole genome sequence of this strain was obtained by paired-end and whole-genome shotgun sequencing, and the gaps between the contigs were closed using gap-spanning PCR products. The P. sp. Cab57 genome is organized into a single circular chromosome with 6,827,892 bp, 63.3% G+C content, and 6,186 predicted protein-coding sequences. Based on 16S rRNA gene analysis and whole genome analysis, strain Cab57 was identified as P. protegens. As reported in P. protegens CHA0 and Pf-5, four gene clusters (phl, prn, plt, and hcn) encoding the typical antibiotic metabolites and the reported genes associated with Gac/Rsm signal transduction pathway of these strains are fully conserved in the Cab57 genome. Actually strain Cab57 exhibited typical Gac/Rsm activities and antibiotic production, and these activities were enhanced by knocking out the retS gene (for a sensor kinase acting as an antagonist of GacS). Two large segments (79 and 115 kb) lacking in the Cab57 genome, as compared with the Pf-5 genome, accounted for the majority of the difference (247 kb) between these genomes. One of these segments was the complete rhizoxin analog biosynthesis gene cluster (ca. 79 kb) and another one was the 115-kb mobile genomic island. A whole genome comparison of those relative strains revealed that each strain has unique gene clusters involved in metabolism such as nitrite/nitrate assimilation, which was identified in the Cab57 genome. These findings suggest that P. protegens is a ubiquitous bacterium that controls its biocontrol traits while building up strain-specific genomic repertoires for the biosynthesis of secondary metabolites and niche adaptation.
Topics: Base Sequence; DNA Transposable Elements; Genome, Bacterial; Japan; Molecular Sequence Data; Operon; Pseudomonas; Species Specificity
PubMed: 24695768
DOI: 10.1371/journal.pone.0093683