The fact that adpA promoter activity is enhanced by S-adenosylmethionine without the involvement of the A-factor/ArpA regulatory cascade Suggests the existence of additional transcriptional regulators for adpA expression in Streptomyces griseus. In this Study, an additional adpA promoter regulatory protein, named ArfA, that is conserved among many bacteria was identified using DNA affinity purification from the cell extracts of Streptomyces lividans. The interactions of ArfA with the adpA promoter from S. griseus and with the bldH promoter from S. lividans were specific and both adpA and bldH promoters required ArfA for the wild-type level of their expressions in S. lividans. bldH of S. lividans is a homolog of adpA of S. lividans. ArfA-deletion mutant had only 70% of the normal undecyprodigiosin production. This result was confirmed by reduced redD promoter activity in the ArfA-deletion mutant. These results suggest that ArfA is a new type of DNA-binding regulator. (c) 2008 Elsevier Inc. All rights reserved.