Abstract
Peptide deformylase (PDF) is an essential enzyme in both gram-negative and gram-positive bacteria. It hydrolyzes formylated N-terminal peptides to generate free N-terminal peptides during the process of protein maturation. Inhibition of this enzyme results in cessation of bacterial growth. We have examined the effect of a potent PDF inhibitor, LBM-415 (also known as VIC-104959), on the proteomes of Staphylococcus aureus and Streptococcus pneumoniae using two-dimensional electrophoresis. Both S. aureus and S. pneumoniae showed accumulation of many N-terminal formylated peptides/proteins upon PDF inhibition. In S. pneumoniae, formylated peptide/protein accumulation was time dependent. Following inhibition, subsequent removal of the inhibitor resulted in deformylation of formylated peptides/proteins; this recovery process was also time dependent. If instead the inhibited cells were maintained in the presence of sub-MIC levels of the PDF inhibitor, the formylated peptides/proteins remained for a much longer time, which correlated with a prolonged postantibiotic effect in vitro. These observations may have broader implications for the application of this class of antibiotics in vivo.