Osterman Ilya A, Khabibullina Nelli F, Komarova Ekaterina S, Kasatsky Pavel, Kartsev Victor G, Bogdanov Alexey A, Dontsova Olga A, Konevega Andrey L, Sergiev Petr V, Polikanov Yury S
Lomonosov Moscow State University, Department of Chemistry and A.N. Belozersky Institute of Physico-Chemical Biology, Moscow 119992, Russia.
Skolkovo Institute of Science and Technology, Skolkovo, Moscow region 143025, Russia.
Nucleic Acids Res. 2017 Jul 7;45(12):7507-7514. doi: 10.1093/nar/gkx413.
The emergence of multi-drug resistant bacteria is limiting the effectiveness of commonly used antibiotics, which spurs a renewed interest in revisiting older and poorly studied drugs. Streptogramins A is a class of protein synthesis inhibitors that target the peptidyl transferase center (PTC) on the large subunit of the ribosome. In this work, we have revealed the mode of action of the PTC inhibitor madumycin II, an alanine-containing streptogramin A antibiotic, in the context of a functional 70S ribosome containing tRNA substrates. Madumycin II inhibits the ribosome prior to the first cycle of peptide bond formation. It allows binding of the tRNAs to the ribosomal A and P sites, but prevents correct positioning of their CCA-ends into the PTC thus making peptide bond formation impossible. We also revealed a previously unseen drug-induced rearrangement of nucleotides U2506 and U2585 of the 23S rRNA resulting in the formation of the U2506•G2583 wobble pair that was attributed to a catalytically inactive state of the PTC. The structural and biochemical data reported here expand our knowledge on the fundamental mechanisms by which peptidyl transferase inhibitors modulate the catalytic activity of the ribosome.
多重耐药细菌的出现限制了常用抗生素的有效性，这激发了人们对重新审视研究较少的老药的新兴趣。链阳性菌素A是一类蛋白质合成抑制剂，其作用靶点是核糖体大亚基上的肽基转移酶中心（PTC）。在这项研究中，我们揭示了PTC抑制剂麦迪霉素II（一种含丙氨酸的链阳性菌素A抗生素）在含有tRNA底物的功能性70S核糖体环境中的作用模式。麦迪霉素II在肽键形成的第一个循环之前抑制核糖体。它允许tRNA与核糖体A位点和P位点结合，但阻止其CCA末端正确定位到PTC中，从而使肽键形成无法进行。我们还揭示了23S rRNA的核苷酸U2506和U2585之前未被发现的药物诱导重排，导致形成U2506•G2583摆动对，这归因于PTC的催化无活性状态。本文报道的结构和生化数据扩展了我们对肽基转移酶抑制剂调节核糖体催化活性基本机制的认识。
