Shigeru KitaniAya IidaTaka aki IzumiAsa MaedaYasuhiro YamadaTakuya NihiraOsaka UniversityMahidol UniversityFukuyama University2018-07-122018-07-122008-12-01Gene. Vol.425, No.1-2 (2008), 9-16037811192-s2.0-53149128699https://repository.li.mahidol.ac.th/handle/123456789/18812The γ-butyrolactone-autoregulator signalling system is widely distributed across many Streptomyces species and it controls secondary metabolism and/or morphological differentiation. IM-2 [(2R,3R,1′R)-2-1′-hydroxybutyl-3-hydroxymethyl-γ-butanolide] is a γ-butyrolactone autoregulator which, in Streptomyces lavendulae FRI-5, switches off the production of d-cycloserine, but switches on the production of several nucleoside antibiotics and blue pigment. In the IM-2 system, an IM-2 specific receptor (FarA) plays a critical role in the biosynthetic regulation of these metabolites, including IM-2 itself. Here, we identified five additional regulatory genes in the farA-flanking region and demonstrated that, in addition to farA, at least two more genes (farR1 and farR2) are involved in the IM-2/FarA system as the direct transcriptional target of FarA. The gel-shift assay revealed that FarA was bound to the upstream region of the four genes (including farR1 and farR2) in an IM-2-dependent manner. The FarA-binding sites were localized by DNase I footprinting to 27- to 33-bp palindromic structures, suggesting that FarA-binding sequences consist of two conserved hexamers separated by six nucleotides. Both farR1 and farR2 were transcribed in a growth-dependent manner, and marked expression was induced in the presence of IM-2, whereas transcripts of other two genes were not detected under the cultivation conditions used. The FarA-binding sites of farR1 and far2 overlap the promoter regions, suggesting that FarA represses the transcription of these two genes in the absence of IM-2 by inhibiting RNA polymerase access. © 2008 Elsevier B.V. All rights reserved.Mahidol UniversityBiochemistry, Genetics and Molecular BiologyArticleSCOPUS10.1016/j.gene.2008.07.043