Cloning and characterisation of an aminopeptidase P-encoding gene from Streptomyces lividans

An aminopeptidase P (PepP)-encoding gene has been cloned from Streptomyces lividans 66 by screening for overexpression of activity using the chromogenic substrate Gly-Pro-beta-naphthylamide as a liquid overlayer on colonies growing on agar medium. The pepP gene was localised by deletion mapping, and the nucleotide sequence was determined. The deduced amino acid sequence was found to display significant similarity to Escherichia coli PepP. The partially purified S. lividans enzyme had a 50-kDa subunit and was present as a homodimer. Direct Edman degradation of the purified protein confirmed that pepP encoded the observed intracellular PepP.