Characterisation of the hydroxystreptomycin phosphotransferase gene (sph) of Streptomyces glaucescens: nucleotide sequence and promoter analysis.

The nucleotide sequence of a 1384 bp fragment containing the coding and promoter sequences of the streptomycin phosphotransferase gene (sph) of the hydroxystreptomycin-producing Streptomyces glaucescens was determined. Evidence for an ATG as translation start codon for sph was derived from a comparison with the amino-terminal amino acid sequence of an aminoglycoside phosphotransferase (aphD gene product) of S. griseus, exhibiting a high degree of amino acid homology to the deduced amino acid sequence of the S. glaucescens sph gene product. Transcriptional start and termination sites for the sph gene were identified by primer extension and/or nuclease S1 mapping experiments. The promoter region of the sph gene appears to be complex since tandemly arranged promoters (orfIp1, orfIp2) initiating transcription of a likely coding region (ORFI) in the opposite direction overlap sph promoter sequences. The presumptive sphp and orfIp1 promoters show considerable sequence similarities in the -10 region to Escherichia coli consensus promoter sequences but no homology to E. coli or Streptomyces -35 regions.