Characterization of peptide deformylase homologues from Staphylococcus epidermidis

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. [Co.sup.2+]-substituted SePDF-1 exhibited much higher enzymic activity ([k.sub.cat]/[K.sub.m] 6.3 x [10.sup.4] [M.sup.-1] [s.sup.-1]) than those of [Ni.sup.2+]-and [Zn.sup.2+]- substituted SePDF-1, and SePDF-1 showed much weaker binding ability towards [Ni.sup.2+] than towards [Co.sup.2+] and [Zn.sup.2+], 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. DOI 10.1099/mic.0.038174-0