Anupam Rajaneesh, Denapoli Leyna, Muchenditsi Abigael, Hines Jennifer V
Department of Chemistry and Biochemistry, Ohio University, Athens, OH 45701, USA.
Bioorg Med Chem. 2008 Apr 15;16(8):4466-70. doi: 10.1016/j.bmc.2008.02.056. Epub 2008 Mar 7.
The T box transcription antitermination mechanism regulates the expression of unique genes in many Gram-positive bacteria by responding, in a magnesium-dependent manner, to uncharged cognate tRNA base pairing with an antiterminator RNA element and other regions of the 5'-untranslated region. Model T box antiterminator RNA is known to bind aminoglycosides, ligands that typically bind RNA in divalent metal ion-binding sites. In this study, enzymatic footprinting and spectroscopic assays were used to identify and characterize the binding site of neomycin B to an antiterminator model RNA. Neomycin B binds the antiterminator bulge nucleotides in an electrostatic-dependent manner and displaces 3-4 monovalent cations, indicating that the antiterminator likely contains a divalent metal ion-binding site. Neomycin B facilitates rather than inhibits tRNA binding indicating that bulge-targeted inhibitors that bind the antiterminator via non-electrostatic interactions may be the more optimal candidates for antiterminator-targeted ligand design.
T盒转录抗终止机制通过以镁依赖的方式响应空载同源tRNA与抗终止子RNA元件以及5'非翻译区的其他区域碱基配对，调控许多革兰氏阳性菌中独特基因的表达。已知T盒抗终止子RNA可结合氨基糖苷类药物，这类配体通常在二价金属离子结合位点与RNA结合。在本研究中，采用酶足迹法和光谱分析来鉴定和表征新霉素B与抗终止子模型RNA的结合位点。新霉素B以静电依赖的方式结合抗终止子凸起核苷酸，并取代3 - 4个单价阳离子，这表明抗终止子可能含有一个二价金属离子结合位点。新霉素B促进而非抑制tRNA结合，这表明通过非静电相互作用结合抗终止子的凸起靶向抑制剂可能是抗终止子靶向配体设计的更优候选物。
