The zinc bound form of the actinomycete derived natural product compound JBIR-141 induces a mitotic phenotype in fission yeast

This study was designed to identify the natural product compound produced by the actinomycete strain “S149” which is capable of inducing a strong small cell phenotype, called wee, in the fission yeast Schizosaccharomyces pombe. We purified the bioactive molecule, which, on the basis of mass spectrometry data, was identified as a novel zinc-bound form of the previously published molecule JBIR-141. JBIR-141 was not previously known to be a zincophore and does not possess structural features common to other bacterial zinc-binding natural product compounds. Testing the effect of the Zn2+ bound form of JBIR-14 against a series of S. pombe deletion mutants which express a wee phenotype suggested its potential target in fission yeast is Pyp1, which is involved in regulation of the onset of mitosis, an important control in the eukaryotic cell cycle

PhoR/PhoP two component regulatory system affects biocontrol capability of Bacillus subtilis NCD-2

The Bacillus subtilis strain NCD-2 is an important biocontrol agent against cotton verticillium wilt and cotton sore shin in the field, which are caused by Verticillium dahliae Kleb and Rhizoctonia solani Kuhn, respectively. A mutant of strain NCD-2, designated M216, with decreased antagonism to V. dahliae and R. solani, was selected by mini-Tn10 mutagenesis and in vitro virulence screening. The inserted gene in the mutant was cloned and identified as the phoR gene, which encodes a sensor kinase in the PhoP/PhoR two-component system. Compared to the wild-type strain, the APase activities of the mutant was decreased significantly when cultured in low phosphate medium, but no obvious difference was observed when cultured in high phosphate medium. The mutant also grew more slowly on organic phosphate agar and lost its phosphatidylcholine-solubilizing ability. The suppression of cotton seedling damping-off in vivo and colonization of the rhizosphere of cotton also decreased in the mutant strain when compared with the wild type strain. All of these characteristics could be partially restored by complementation of the phoR gene in the M216 mutant

Screening and purification of natural products from Actinomycetes that affect the cell shape of fission yeast

This study was designed to identify bioactive compounds that alter the cellular shape of the fission yeast Schizosaccharomyces pombe by affecting functions involved in the cell cycle or cell morphogenesis. We used a multidrug-sensitive fission yeast strain, SAK950 to screen a library of 657 actinomycete bacteria and identified 242 strains that induced eight different major shape phenotypes in S. pombe These include the typical cell cycle-related phenotype of elongated cells, and the cell morphology-related phenotype of rounded cells. As a proof of principle, we purified four of these activities, one of which is a novel compound and three that are previously known compounds, leptomycin B, streptonigrin and cycloheximide. In this study, we have also shown novel effects for two of these compounds, leptomycin B and cycloheximide. The identification of these four compounds and the explanation of the S. pombe phenotypes in terms of their known, or predicted bioactivities, confirm the effectiveness of this approach