Isolation and some properties of a novel killer toxin-like protein produced by Streptomyces sp F-287

A killer toxin-like protein was found in the culture supernatant of a strai n isolated from soil. The strain was classified and designated as Streptomy ces sp. F-287. The molecular weight of the purified killer toxin-like prote in was estimated to be 9,500 by SDS-PAGE. The purified protein was heat sta ble (100 degrees C, 5 min), pH stable (pH 6.0-9.0, 60 degrees C, for 30 min ), and had a relatively wide action spectra. The SKLP showed a cytocidal ef fect on both budding yeast, Saccharomyces cerevisiae W303 (IC50=15.6 mu g/m l) and on fission yeast, Schizosaccharomyces pombe SP870 (IC50=20.0 mu g/ml ). The SKLP also caused morphological changes on some sensitive yeasts and filamentous fungi. These characteristics are apparently different from know n killer toxins. These results suggest that this is a novel killer toxin-li ke protein from Streptomyces sp. strain F-287.