Shaw Jeffrey J, Trobro Stefan, He Shan L, Åqvist Johan, Green Rachel
Department of Molecular Biology and Genetics, Howard Hughes Medical Institute, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA.
Chem Biol. 2012 Aug 24;19(8):983-93. doi: 10.1016/j.chembiol.2012.06.011.
The 2' OH of the peptidyl-tRNA substrate is thought to be important for catalysis of both peptide bond formation and peptide release in the ribosomal active site. The release reaction also specifically depends on a release factor protein (RF) to hydrolyze the ester linkage of the peptidyl-tRNA upon recognition of stop codons in the A site. Here, we demonstrate that certain amino acid substitutions (in particular those containing hydroxyl or thiol groups) in the conserved GGQ glutamine of release factor RF1 can rescue defects in the release reaction associated with peptidyl-tRNA substrates lacking a 2' OH. We explored this rescue effect through biochemical and computational approaches that support a model where the 2' OH of the P-site substrate is critical for orienting the nucleophile in a hydrogen-bonding network productive for catalysis.
肽基 - tRNA底物的2'-羟基被认为对核糖体活性位点中肽键形成和肽释放的催化作用都很重要。释放反应还特别依赖于一种释放因子蛋白（RF），该蛋白在识别A位点的终止密码子后水解肽基 - tRNA的酯键。在这里，我们证明了释放因子RF1保守的GGQ谷氨酰胺中的某些氨基酸取代（特别是那些含有羟基或巯基的取代）可以挽救与缺乏2'-羟基的肽基 - tRNA底物相关的释放反应缺陷。我们通过生化和计算方法探索了这种挽救作用，这些方法支持一种模型，即P位点底物的2'-羟基对于在有利于催化的氢键网络中定位亲核试剂至关重要。
