A gene homologous to the Streptomyces chymotrypsin-like protease (SAM-p20) gene is tandemly located.

A gene encoding a homolog of the Streptomyces chymotrypsin-like serine protease, SAM-P20, was identified downstream of the sam-p20 gene and designated SAM-P20D. This gene has two tandem Shine Dalgarno sequences and two initiation codons. We have established vector systems with the function of tyrosinase gene-bone melanin pigmentation as a reporter for sam-p20D gene expression in Streptomyces coelicolor in order to identify the promoter and terminator activities. Using this system, the sam-p20D gene was suggested to be transcribed monocistronically.