Properties of C-terminal truncated derivatives of the activator, StrR, of the streptomycin biosynthesis in Streptomyces griseus.

The StrR protein is a DNA-binding protein activating the transcription of streptomycin biosynthesis of Streptomyces griseus N2-3-11 and Streptomyces glaucescens. A putative helix-turn-helix motif located between amino acid positions 207 and 227 of the StrR protein was identified as a prerequisite for its DNA-binding properties. Although, C-terminal truncated StrR proteins were able to interact with StrR-binding sites, they failed to activate transcription from the StrR-dependent promotor strB1p. Therefore, the C-terminal domain of StrR seemed to be necessary for its function as transcriptional activator.