Transcription factor; part of the gene cluster that mediates the biosynthesis of heptelidic acid (HA), a sesquiterpene lactone that acts as an inhibitor of glyceraldehyde-3-phosphatedehydrogenase (GAPDH) and a growth inhibitor of the salt-tolerant lactic acid bacteria in soy sauce brewing (PubMed:30466366). Both hepR and hepS regulate the transcription of the heptelidic acid cluster, but they are not involved in mutual transcriptional regulation and act with different mechanisms (PubMed:30466366). Reduces markedly the expression of hepA and abolishes the production of heptelidic acid. Belongs to the TRI10 transcription regulator family.