Characterization of peptide deformylase homologues from Staphylococcus epidermidis

Abstract

The emergence of multi-drug-resistant strains of Staphylococcus epidermidis emphasizes the need to develop new antibiotics. The unique and essential role of the peptide deformylase (PDF) in catalysing the removal of the N-terminal formyl group from newly synthesized polypeptides in eubacteria makes it an attractive antibacterial drug target. In the present study, both deformylase homologues from S. epidermidis (SePDF-1 and SePDF-2) were cloned and expressed, and their enzymic activities were characterized. Co2+-substituted SePDF-1 exhibited much higher enzymic activity (k cat/K m 6.3×104 M−1 s−1) than those of Ni2+- and Zn2+-substituted SePDF-1, and SePDF-1 showed much weaker binding ability towards Ni2+ than towards Co2+ and Zn2+, which is different from PDF in Staphylococcus aureus (SaPDF), although they share 80 % amino-acid sequence identity. The determined crystal structure of SePDF-1 was similar to that of (SaPDF), except for differences in the metal-binding sites. The other deformylase homologue, SePDF-2, was shown to have no peptide deformylase activity; the function of SePDF-2 needs to be further investigated.