How does Mupirocin affect bacterial protein synthesis?

Mupirocin is a topical antibiotic that specifically interferes with bacterial protein synthesis by binding to bacterial isoleucyl transfer-RNA synthetase. This enzyme is crucial for the incorporation of the amino acid isoleucine into nascent proteins. By binding to this enzyme, mupirocin effectively inhibits the activation and subsequent incorporation of isoleucine, which is essential for the synthesis of certain proteins required for bacterial growth and survival.

This mechanism of action is significant for treating localized infections caused by gram-positive bacteria, particularly Staphylococcus aureus, including methicillin-resistant strains (MRSA). The inability of bacteria to correctly synthesize proteins due to mupirocin's action leads to their inability to function or proliferate effectively.

Understanding this specific mechanism clarifies why other options do not apply to mupirocin's action. The formation of the cell wall is not directly affected by mupirocin, nor does it inhibit RNA polymerase or prevent DNA gyrase activity, which are targets for different classes of antibiotics. Thus, the choice indicating that mupirocin binds to isoleucyl transfer-RNA synthetase accurately describes its unique role in inhibiting bacterial protein synthesis.