Lin A H, Murray R W, Vidmar T J, Marotti K R
Molecular Biology Research, Pharmacia & Upjohn, Kalamazoo, Michigan 49007, USA.
Antimicrob Agents Chemother. 1997 Oct;41(10):2127-31. doi: 10.1128/AAC.41.10.2127.
The oxazolidinones are a novel class of antibiotics that act by inhibiting protein synthesis. It as been reported that the drug exerts its primary activity on the initiation phase of translation. In order to study the possibility of direct interaction between the drug and the ribosome, we have developed a binding assay using 14C-labelled eperezolid (PNU-100592; formerly U-100592). Eperezolid binds specifically to the 50S ribosomal subunit of Escherichia coli. The specific binding of eperezolid is dose dependent and is proportional to the ribosome concentrations. Scatchard analysis of the binding data reveals that the dissociation constant (Kd) is about 20 microM. The binding of eperezolid to the ribosome is competitively inhibited by chloramphenicol and lincomycin. However, unlike chloramphenicol and lincomycin, eperezolid does not inhibit the puromycin reaction, indicating that the oxazolidinones have no effect on peptidyl transferase. In addition, whereas lincomycin and, to some extent, chloramphenicol inhibit translation termination, eperezolid has no effect. Therefore, we conclude that the oxazolidinones inhibit protein synthesis by binding to the 50S ribosomal subunit at a site close to the site(s) to which chloramphenicol and lincomycin bind but that the oxazolidinones are mechanistically distinct from these two antibiotics.
恶唑烷酮类是一类新型抗生素，其作用机制是抑制蛋白质合成。据报道，该药物在翻译起始阶段发挥主要活性。为了研究该药物与核糖体直接相互作用的可能性，我们开发了一种使用14C标记的依哌唑胺（PNU - 100592；原U - 100592）的结合试验。依哌唑胺特异性结合大肠杆菌的50S核糖体亚基。依哌唑胺的特异性结合呈剂量依赖性，且与核糖体浓度成正比。对结合数据进行Scatchard分析表明，解离常数（Kd）约为20微摩尔。依哌唑胺与核糖体的结合受到氯霉素和林可霉素的竞争性抑制。然而，与氯霉素和林可霉素不同的是，依哌唑胺不抑制嘌呤霉素反应，这表明恶唑烷酮类对肽基转移酶没有影响。此外，虽然林可霉素以及在一定程度上氯霉素会抑制翻译终止，但依哌唑胺没有此作用。因此，我们得出结论，恶唑烷酮类通过与50S核糖体亚基上靠近氯霉素和林可霉素结合位点的一个位点结合来抑制蛋白质合成，但恶唑烷酮类在作用机制上与这两种抗生素不同。
