Butenolides from Streptomyces albus J1074 Act as External Signals To Stimulate Avermectin Production in Streptomyces avermitilis.

In streptomycetes, autoregulators are important signaling compounds that trigger secondary metabolism, and they are regarded as hormones based on their extremely low effective concentrations (nM) and the involvement of specific receptor proteins. Our previous distribution study revealed that butenolide-type hormones, including avenolide, are a general class of signaling molecules in streptomycetes and that strain J1074 may produce butenolide-type hormones. Here, we describe metabolite profiling of a disruptant of the gene, which encodes a key biosynthetic enzyme for butenolide-type hormones, and identify four butenolide compounds from J1074 that show avenolide activity. The compounds structurally resemble avenolide and show different levels of avenolide activity. A dual-culture assay with imaging mass spectrometry (IMS) analysis for metabolic profiling demonstrated that the butenolide compounds of J1074 stimulate avermectin production in another species, , illustrating the complex chemical interactions through interspecies signals in streptomycetes. Microorganisms produce external and internal signaling molecules to control their complex physiological traits. In actinomycetes, hormones are low-molecular-weight signals that are key to our understanding of the regulatory mechanisms of secondary metabolism. This study reveals that acyl coenzyme A (acyl-CoA) oxidase is a common and essential biosynthetic enzyme for butenolide-type hormones. Moreover, the diffusible butenolide compounds from a donor strain were recognized by the recipient strain of a different species, resulting in the initiation of secondary metabolism in the recipient. This is an interesting report on the chemical interaction between two different streptomycetes via hormones. Information on the metabolite network may provide useful hints not only to clarification of the regulatory mechanism of secondary metabolism, but also to understanding of the chemical communication among streptomycetes to control their physiological traits.