<jats:title>ABSTRACT</jats:title><jats:sec><jats:label/><jats:p>γ‐Butyrolactones (GBLs), such as A‐factor, are one type of signaling molecules produced by <jats:italic>Streptomyces</jats:italic> species and have been reported to regulate secondary metabolism. However, they are usually produced in very small amount, which has hindered their structural elucidation and application for antibiotic overproduction. In this work, 1,4‐butyrolactone (1,4‐BL), as an easily accessible and cheap analogue of GBLs, was applied to the fermentation of validamycin A (VAL‐A), an important antifungal antibiotic produced by <jats:italic>Streptomyces hygroscopicus</jats:italic> 5008. The addition of 1,4‐BL enhanced VAL‐A production by 30% in both shaking flasks and bioreactors. The transcriptional levels of the <jats:italic>adpA</jats:italic> homologue (<jats:italic>adpA–H</jats:italic>) and VAL‐A biosynthetic genes were significantly increased. Among the three A‐factor receptor homologous genes identified in the genome of <jats:italic>S. hygroscopicus</jats:italic> 5008, <jats:italic>shbR3</jats:italic> was proved to be responsible for the inducing activity of 1,4‐BL by gene disruption and circular dichroism analysis, and ShbR3 could bind to the promoter region of <jats:italic>adpA–H</jats:italic> as indicated by EMSA analysis. Furthermore, the mutation of <jats:italic>adpA–H</jats:italic> abolished the transcription of VAL‐A biosynthetic genes and VAL‐A productivity. In EMSA analysis, AdpA–H could directly bind to the promoter regions of VAL‐A gene cluster. Moreover, addition of the 1,4‐BL also improved the VAL‐A production in a high‐yielding strain TL01. The results showed that 1,4‐BL could stimulate A‐factor‐like cascade and subsequently enhance VAL‐A production in <jats:italic>S. hygroscopicus</jats:italic> 5008. Biotechnol. Bioeng. 2013;110: 2984–2993. © 2013 Wiley Periodicals, Inc.</jats:sec>