RESUMEN
A strain of Streptomyces nodosus (NPS007994) isolated from a marine sediment collected in Scripps Canyon, La Jolla, California, was found to produce lajollamycin (1), a nitro-tetraene spiro-beta-lactone-gamma-lactam antibiotic. The structure was established by complete analysis of spectroscopic data and comparison with known antibiotics oxazolomycin (2), 16-methyloxazolomycin (3), and triedimycin B (4). Lajollamycin (1) showed antimicrobial activity against both drug-sensitive and -resistant Gram-positive bacteria and inhibited the growth of B16-F10 tumor cells in vitro.
Asunto(s)
Antibacterianos/aislamiento & purificación , Antineoplásicos/aislamiento & purificación , Lactamas/aislamiento & purificación , Compuestos de Espiro/aislamiento & purificación , Streptomyces/química , Animales , Antibacterianos/química , Antibacterianos/farmacología , Antineoplásicos/química , Antineoplásicos/farmacología , California , Línea Celular Tumoral , Ensayos de Selección de Medicamentos Antitumorales , Bacterias Grampositivas/efectos de los fármacos , Lactamas/química , Lactamas/farmacología , Ratones , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Oxazoles/química , Alcamidas Poliinsaturadas , Compuestos de Espiro/química , Compuestos de Espiro/farmacologíaRESUMEN
To address the need for new approaches to antibiotic drug development, we have identified a large number of essential genes for the bacterial pathogen, Staphylococcus aureus, using a rapid shotgun antisense RNA method. Staphylococcus aureus chromosomal DNA fragments were cloned into a xylose-inducible expression plasmid and transformed into S. aureus. Homology comparisons between 658 S. aureus genes identified in this particular antisense screen and the Mycoplasma genitalium genome, which contains 517 genes in total, yielded 168 conserved genes, many of which appear to be essential in M. genitalium and other bacteria. Examples are presented in which expression of an antisense RNA specifically reduces its cognate mRNA. A cell-based, drug-screening assay is also described, wherein expression of an antisense RNA confers specific sensitivity to compounds targeting that gene product. This approach enables facile assay development for high throughput screening for any essential gene, independent of its biochemical function, thereby greatly facilitating the search for new antibiotics.