PBP2a protein

The mecA gene is found in bacterial cells that allows a bacterium to be resistant to antibiotics such as methicillin, penicillin and other penicillin-like antibiotics. mecA is located on the staphylococcal chromosome cassette mec that encodes the protein PBP2A (penicillin binding protein 2A) which has a low affinity for beta-lactam antibiotics such as methicillin and penicillin. This enables transpeptidase activity in the presence of beta-lactams, preventing them from inhibiting cell wall synthesis. Penicillin, its derivatives and methicilin, are beta-lactams that all work by disrupting the mechanical structure of the bacterial cell wall by reacting with the cell wall forming penicillin-binding protein family (PBP 1,2, 3 and 4), causing the cytoplasm to leak and the cell to die. However, the mecA gene codes for PBP2a that has lower affinity for antibiotic drugs, and keeps the structural integrity of the cell wall, preventing cell death.