Cuevaenes A and B, new polyene carboxylic acids from Streptomyces sp. HKI 0180.
In the course of a screening for newmetabolites from strains of actinomycetes we disclosed Streptomyces sp. HKI 0180 as the producer of cuevaenes A (1) and B (2). The strain was isolated from a soil sample from the cave of Altamira (Spain). In this paper we report the production, isolation, structure elucidation and biological properties of 1 and 2 (Fig. 1). An agar slant culture of the above strain was used to inoculate a 500 ml Erlenmeyer flask containing 100ml of a seed medium composed of (g/liter): dextrose 15, soya bean meal 15, NaCl 5, CaCO3 1, KH2PO4 0.4, distilled water, pH 6.9. The producing medium contained (g/liter): mannitol 20, soya bean meal 20, distilled water, pH6.5.
Identification and Characterization of the Cuevaene A Biosynthetic Gene Cluster in Streptomyces sp. LZ35
Genome sequence analysis of Streptomyces sp. LZ35 has revealed a large number of secondary metabolite pathways, including one encoded in an orphan type I polyketide synthase gene cluster that contains a putative chorismatase/3‐hydroxybenzoate synthase gene. Mutagenesis and comparative metabolic profiling led to the identification of cuevaene A as the metabolic product of the gene cluster, thus making it the first 3‐HBA containing polyketide biosynthetic gene cluster described to date. Cuv10 was proven to be responsible for the conversion of chorismate into 3‐HBA; Cuv18 is speculated to be responsible for the 6‐hydroxylation of 3‐HBA during polyketide chain elongation. Additionally, several pathway‐specific regulatory factors that affect the production of cuevaene A were identified. Our results indicate that targeted inactivation of a gene followed by comparative metabolic profiling is a useful approach to identify and characterize cryptic biosynthetic gene clusters.
New polyenic antibiotics active against gram-positive and gram-negative bacteria. V. Mode of action of enacyloxin IIa.
The chemical structure of a unique polyenic antibiotic enacyloxin IIa (former name: fr. 2) produced by Frateuria (formerly Gluconobacter) sp. W-315 has been determined by extensive spectroscopic studies, in particular by NMR spectral analysis. It has a novel non-lactonic structure involving 3, 4-dihydroxycyclohexanecarboxylic acid with a chlorine-containing polyenic and polyhydroxy acyl side chain attached as an ester to the 3-hydroxyl substituent of the acid.