1 research outputs found
Activity-Independent Discovery of Secondary Metabolites Using Chemical Elicitation and Cheminformatic Inference
Most existing antibiotics were discovered
through screens of environmental
microbes, particularly the streptomycetes, for the capacity to prevent
the growth of pathogenic bacteria. This “activity-guided screening”
method has been largely abandoned because it repeatedly rediscovers
those compounds that are highly expressed during laboratory culture.
Most of these metabolites have already been biochemically characterized.
However, the sequencing of streptomycete genomes has revealed a large
number of “cryptic” secondary metabolic genes that are
either poorly expressed in the laboratory or that have biological
activities that cannot be discovered through standard activity-guided
screens. Methods that reveal these uncharacterized compounds, particularly
methods that are not biased in favor of the highly expressed metabolites,
would provide direct access to a large number of potentially useful
biologically active small molecules. To address this need, we have
devised a discovery method in which a chemical elicitor called Cl-ARC
is used to elevate the expression of cryptic biosynthetic genes. We
show that the resulting change in product yield permits the direct
discovery of secondary metabolites without requiring knowledge of
their biological activity. We used this approach to identify three
rare secondary metabolites and find that two of them target eukaryotic
cells and not bacterial cells. In parallel, we report the first paired
use of cheminformatic inference and chemical genetic epistasis in
yeast to identify the target. In this way, we demonstrate that oxohygrolidin,
one of the eukaryote-active compounds we identified through activity-independent
screening, targets the V1 ATPase in yeast and human cells and secondarily
HSP90