Chertov O Iu, Obukhov A N, Lipkin V M
Bioorg Khim. 1983 May;9(5):633-40.
By fluorimetric titration of Rifs (E. coli B) and Rifr (E. coli rpoB255) RNA polymerases with rifamycin, the mutant polymerase was demonstrated to bind rifamycin. A comparison of spatial structures of rifamycin and dinucleotide fragment of RNA in the hybrid with DNA revealed their similarity. Taking into account this structural similarity and also the fact that two phosphodiester bonds can be formed by RNA polymerase in the presence of rifamycin, a model for the inhibition mode was proposed. According to this model, rifamycin occupies the place of two terminal nucleotides of synthesized, but not translocated pentanucleotide in the transcribing complex. Asp-516 of the wild type beta-subunit was assumed to form a hydrogen bond with the rifamycin C(23) hydroxyl group. On the base of this model, reduced "cycling" synthesis of tetra-, penta-... up to decanucleotides by the Rifr RNA polymerase, in comparison with Rifs, was predicted.
通过用利福霉素对利福平敏感型（大肠杆菌B）和利福平耐药型（大肠杆菌rpoB255）RNA聚合酶进行荧光滴定，证明突变型聚合酶能结合利福霉素。对利福霉素与RNA二核苷酸片段在与DNA杂交体中的空间结构进行比较，发现它们具有相似性。考虑到这种结构相似性以及在利福霉素存在下RNA聚合酶可形成两个磷酸二酯键这一事实，提出了一种抑制模式模型。根据该模型，利福霉素在转录复合物中占据已合成但未转位的五核苷酸的两个末端核苷酸位置。野生型β亚基的Asp-516被认为与利福霉素C(23)羟基形成氢键。基于该模型，预测与利福平敏感型RNA聚合酶相比，利福平耐药型RNA聚合酶合成四核苷酸、五核苷酸……直至十核苷酸的“循环”合成减少
