Question

Penicillin-binding proteins primarily function in the cell to ________.

1) bind to beta-lactam drugs
2) are enzymes
3) are involved in cell wall synthesis
4) inhibit non-growing bacteria
5) are enzymes AND are involved in cell wall synthesis

Answer 1

Penicillin-binding proteins are enzymes involved in the synthesis of the bacterial cell wall. They perform cross-linking of peptidoglycan chains, and are targeted by β-lactam antibiotics like penicillin, rendering bacteria susceptible to lysis.

Step-by-step explanation:

Penicillin-binding proteins (PBPs) primarily function in the cell to synthesize the bacterial cell wall and are also enzymes that participate in this process. PBPs are responsible for the cross-linking of peptidoglycan chains which is essential for cell wall integrity. Penicillin and other β-lactam antibiotics target these proteins, binding to them and preventing them from forming cross-links in the peptidoglycan layer. This results in a weakening of the cell wall and makes bacteria susceptible to osmotic lysis. Because human cells do not have cell walls, they are not affected by these antibiotics, showcasing selective toxicity. Among the options provided, number 5 accurately represents the dual role of PBPs as both enzymes and integral participants in cell wall synthesis.