A [3Fe-4S] cluster and tRNA-dependent aminoacyltransferase BlsK in the biosynthesis of Blasticidin S.

Blasticidin S is a peptidyl nucleoside antibiotic. Its biosynthesis involves a cryptic leucylation and two leucylated intermediates, LDBS and LBS, have been found in previous studies. Leucylation has been proposed to be a new self-resistance mechanism during blasticidin S biosynthesis, and the leucyl group was found to be important for the methylation of β-amino group of the arginine side chain.

An Interspecies Signaling System Mediated by Fusaric Acid Has Parallel Effects on Antifungal Metabolite Production by Pseudomonas protegens Strain Pf-5 and Antibiosis of Fusarium spp.

Pseudomonas protegens strain Pf-5 is a rhizosphere bacterium that suppresses soilborne plant diseases and produces at least seven different secondary metabolites with antifungal properties. We derived mutants of Pf-5 with single and multiple mutations in biosynthesis genes for seven antifungal metabolites: 2,4-diacetylphoroglucinol (DAPG), pyrrolnitrin, pyoluteorin, hydrogen cyanide, rhizoxin, orfamide A, and toxoflavin. These mutants were tested for inhibition of the pathogens Fusarium verticillioides and Fusarium oxysporum f.

Identification of Elaiophylin Skeletal Variants from the Indonesian Streptomyces sp. ICBB 9297.

Four new elaiophylin macrolides (1-4), together with five known elaiophylins (5-9), have been isolated from cultures of the Indonesian soil bacterium Streptomyces sp. ICBB 9297. The new compounds have macrocyclic skeletons distinct from those of the known dimeric elaiophylins in that one or both of the polyketide chains contain(s) an additional pendant methyl group.

Succinylated Apoptolidins from Amycolatopsis sp. ICBB 8242.

Two new apoptolidins, 2'-O-succinyl-apoptolidin A (11) and 3'-O-succinyl-apoptolidin A (12), were isolated from the culture broth of an Indonesian Amycolatopsis sp. ICBB 8242. These compounds inhibit the proliferation and viability of human H292 and HeLa cells.

Apoptolidins A and C activate AMPK in metabolically sensitive cell types and are mechanistically distinct from oligomycin A.

Apoptolidin A was first isolated as a secondary metabolite of a Nocardiopsis sp. and is the founding member of a family of potential selective cancer cell toxins. We now report the isolation, production and pharmacological characterization of apoptolidins A and C from an alternate actinomycete producer, an Amycolatopsis sp.

Pseudomonas protegens Pf-5 causes discoloration and pitting of mushroom caps due to the production of antifungal metabolites.

Bacteria in the diverse Pseudomonas fluorescens group include rhizosphere inhabitants known for their antifungal metabolite production and biological control of plant disease, such as Pseudomonas protegens Pf-5, and mushroom pathogens, such as Pseudomonas tolaasii. Here, we report that strain Pf-5 causes brown, sunken lesions on peeled caps of the button mushroom (Agaricus bisporus) that resemble brown blotch symptoms caused by P. tolaasii.

Mefloquine and psychotomimetics share neurotransmitter receptor and transporter interactions in vitro.

Rationale: Mefloquine is used for the prevention and treatment of chloroquine-resistant malaria, but its use is associated with nightmares, hallucinations, and exacerbation of symptoms of post-traumatic stress disorder. We hypothesized that potential mechanisms of action for the adverse psychotropic effects of mefloquine resemble those of other known psychotomimetics.

Objectives: Using in vitro radioligand binding and functional assays, we examined the interaction of (+)- and (-)-mefloquine enantiomers, the non-psychotomimetic anti-malarial agent, chloroquine, and several hallucinogens and psychostimulants with recombinant human neurotransmitter receptors and transporters.

Structural and functional characterization of MppR, an enduracididine biosynthetic enzyme from streptomyces hygroscopicus: functional diversity in the acetoacetate decarboxylase-like superfamily.

The nonproteinogenic amino acid enduracididine is a critical component of the mannopeptimycins, cyclic glycopeptide antibiotics with activity against drug-resistant pathogens, including methicillin-resistant Staphylococcus aureus. Enduracididine is produced in Streptomyces hygroscopicus by three enzymes, MppP, MppQ, and MppR. On the basis of primary sequence analysis, MppP and MppQ are pyridoxal 5'-phosphate-dependent aminotransferases; MppR shares a low, but significant, level of sequence identity with acetoacetate decarboxylase.

Streptomyces lividans blasticidin S deaminase and its application in engineering a blasticidin S-producing strain for ease of genetic manipulation.

Blasticidin S is a peptidyl nucleoside antibiotic produced by Streptomyces griseochromogenes that exhibits strong fungicidal activity. To circumvent an effective DNA uptake barrier system in the native producer and investigate its biosynthesis in vivo, the blasticidin S biosynthetic gene cluster (bls) was engrafted to the chromosome of Streptomyces lividans. However, the resulting mutant, LL2, produced the inactive deaminohydroxyblasticidin S instead of blasticidin S.

Analysis of the mildiomycin biosynthesis gene cluster in Streptoverticillum remofaciens ZJU5119 and characterization of MilC, a hydroxymethyl cytosyl-glucuronic acid synthase.

Mildiomycin (MIL) is a peptidyl-nucleoside antibiotic produced by Streptoverticillum remofaciens ZJU5119 that exhibits strong inhibitory activity against powdery mildew. The entire MIL biosynthesis gene cluster was cloned and expressed in Streptomyces lividans 1326. Systematic gene disruptions narrowed down the cluster to 16 functional ORFs and identified the boundaries of the gene cluster.

Phloroglucinol mediates cross-talk between the pyoluteorin and 2,4-diacetylphloroglucinol biosynthetic pathways in Pseudomonas fluorescens Pf-5.

The antibiotics pyoluteorin and 2,4-diacetylphloroglucinol (DAPG) contribute to the biological control of soilborne plant diseases by some strains of Pseudomonas fluorescens, including Pf-5. These secondary metabolites also have signalling functions with each compound reported to induce its own production and repress the other's production. The first step in DAPG biosynthesis is production of phloroglucinol (PG) by PhlD.

Enduracidin analogues with altered halogenation patterns produced by genetically engineered strains of Streptomyces fungicidicus.

Enduracidins (1, 2) and ramoplanin (3) are structurally and functionally closely related lipodepsipeptide antibiotics. They are active against multi-drug-resistant Gram-positive pathogens, including MRSA. Each peptide contains one chlorinated non-proteinogenic amino acid residue, Cl(2)-Hpg or Cl-Hpg.

Deep-sea hydrothermal vents: potential hot spots for natural products discovery?

Deep-sea hydrothermal vents are among the most extreme and dynamic environments on Earth. However, islands of highly dense and biologically diverse communities exist in the immediate vicinity of hydrothermal vent flows, in stark contrast to the surrounding bare seafloor. These communities comprise organisms with distinct metabolisms based on chemosynthesis and growth rates comparable to those from shallow water tropical environments, which have been rich sources of biologically active natural products.

Modified phenazines from an Indonesian Streptomyces sp.

Fractionation of the extract from the Indonesian Streptomyces sp. ICBB8198 as directed by the antibacterial activity delivered the known phenazine antibiotics griseoluteic acid (1a) and griseolutein A (1b), as well as two new phenazine derivatives (2 and 3). In addition, the known compounds spirodionic acid, dihydrosarkomycins, and 6-ethyl-4-hydroxy-3,5-dimethyl-2H-pyran-2-one (4a), along with the new pyrone 3,6-diethyl-4-hydroxy-5-methyl-2H-pyran-2-one (4b), were isolated.

Inactivation of the GacA response regulator in Pseudomonas fluorescens Pf-5 has far-reaching transcriptomic consequences.

The GacS/GacA signal transduction system is a central regulator in Pseudomonas spp., including the biological control strain P. fluorescens Pf-5, in which GacS/GacA controls the production of secondary metabolites and exoenzymes that suppress plant pathogens.

Control of steroid 21-oic acid synthesis by peroxisome proliferator-activated receptor alpha and role of the hypothalamic-pituitary-adrenal axis.

A previous study identified the peroxisome proliferator-activated receptor alpha (PPARalpha) activation biomarkers 21-steroid carboxylic acids 11beta-hydroxy-3,20-dioxopregn-4-en-21-oic acid (HDOPA) and 11beta,20-dihydroxy-3-oxo-pregn-4-en-21-oic acid (DHOPA). In the present study, the molecular mechanism and the metabolic pathway of their production were determined. The PPARalpha-specific time-dependent increases in HDOPA and 20alpha-DHOPA paralleled the development of adrenal cortex hyperplasia, hypercortisolism, and spleen atrophy, which was attenuated in adrenalectomized mice.

Limazepines A-F, pyrrolo[1,4]benzodiazepine Antibiotics from an Indonesian Micrococcus sp.

In our screening of Indonesian microorganisms for novel bioactive natural products we have isolated seven new compounds, designated as limazepines A, B1 and B2 (isolated as an isomeric mixture), C, D, E, and F, from the culture broth of Micrococcus sp. strain ICBB 8177. In addition, the known natural products prothracarcin and 7-O-succinylmacrolactin A, as well as two previously reported synthetic compounds, 2-amino-3-hydroxy-4-methoxybenzoic acid methyl ester and 4-ethylpyrrole-2-carboxaldehyde, were obtained from the extract.

Rearranged and unrearranged angucyclinones from Indonesian Streptomyces spp.

Two Indonesian Streptomyces strains, ICBB8309 and ICBB8415, were investigated for their ability to produce antibiotic compounds. In addition to the known antibiotics actiphenol, naramycin B, and sabaramycin, six new angucyclinones were identified. The isolation, structure elucidation and biological activities for the six new compounds are presented.

The mildiomycin biosynthesis: initial steps for sequential generation of 5-hydroxymethylcytidine 5'-monophosphate and 5-hydroxymethylcytosine in Streptoverticillium rimofaciens ZJU5119.

Mildiomycin (MIL) is a peptidyl nucleoside antibiotic with strong activity against powdery mildew disease of plants. We have cloned the MIL biosynthetic gene cluster in Streptoverticillum rimofaciens ZJU5119 and shown that this organism also produces the related antifungal compound, deshydroxymethyl mildiomycin (dHM-MIL). A cosmid genomic library was screened for a putative nucleotide hydrolase gene that is related to blsM from the blasticidin S cluster.

Angucyclinones from an Indonesian Streptomyces sp.

Six new angucyclinone polyketides named panglimycins A-F were isolated together with the three known metabolites (+)-fujianmycin A, (+)-ochromycinone, and emycin C from the bioassay-guided fractionation of the extract of the Indonesian Streptomyces strain ICBB8230. The new compounds are highly oxygenated angucyclinones that appear to be biosynthetically derived from ochromycinone or fujianmycin. Their structures were determined by X-ray crystal analysis, interpretation of 1D- and 2D-NMR spectra, and comparison of the data with those of structurally related known natural products.

Roles of VioG and VioQ in the incorporation and modification of the Capreomycidine residue in the peptide antibiotic viomycin.

The nonproteinogenic amino acid capreomycidine is the signature residue found in the tuberactinomycin family of antitubercular peptide antibiotics and an important element of the pharmacophore. Recombinant VioG, a single-module peptide synthetase from the viomycin gene cluster cloned from Streptomyces vinaceus (ATCC11861), specifically activates capreomycidine for incorporation into viomycin (tuberactinomycin B). Insertional disruption of the putative hydroxylase gene vioQ resulted in a mutant that accumulated tuberactinomycin O, suggesting that hydroxylation at C-5 of the capreomycidine residue is a post-assembly event.

The enduracidin biosynthetic gene cluster from Streptomyces fungicidicus.

The biosynthetic gene cluster for the 17 aa peptide antibiotic enduracidin has been cloned and sequenced from Streptomyces fungicidicus ATCC 21013. The 84 kb gene cluster contains 25 ORFs and is located within a 116 kb genetic locus that was fully sequenced. Targeted disruption of non-ribosomal peptide synthetase (NRPS) genes in the cluster abolished enduracidin production and confirmed function.

Molecular and biochemical studies of chondramide formation-highly cytotoxic natural products from Chondromyces crocatus Cm c5.

The jaspamide/chondramide family of depsipeptides are mixed PKS/NRPS natural products isolated from marine sponges and a terrestrial myxobacterium that potently affect the function of the actin cytoskeleton. As a first step to improve production in heterologous host cells and permit genetic approaches to novel analogs, we have cloned and characterized the chondramide biosynthetic genes from the myxobacterium Chondromyces crocatus Cm c5. In addition to the expected PKS and NRPS genes, the cluster encodes a rare tyrosine aminomutase for beta-tyrosine formation and a previously unknown tryptophan-2-halogenase.