Construction of a modified penicillin-binding protein 2a from methicillin-resistant Staphylococcus aureus and purification by immobilized metal affinity chromatography.

The mecA-27r gene, which encodes PBP2a-27r, was modified by site-specific mutagenesis, resulting in replacement of the N-terminal membrane anchor with a short chelating peptide (CP-PBP2a-27r). CP-PBP2a-27r retained the same binding affinity for beta-lactam antibiotics as the wild-type enzyme. Approximately 95% pure CP-PBP2a-27r was recovered in a single step by use of chelating-peptide-immobilized metal ion affinity chromatography.