Division of Biological Sciences, The University of Montana, Missoula, MT 59812, USA.
J Mol Biol. 2010 Aug 20;401(3):493-502. doi: 10.1016/j.jmb.2010.06.047. Epub 2010 Jun 30.
Ribosomal protein S20 is a primary binding protein that bridges the 5' domain and the 3' minor domain of the 16S ribosomal RNA (rRNA) in the 30S ribosomal subunit. Using time-dependent dimethyl sulfate modification, we have determined that as it is bound to 16S rRNA, protein S20 causes rapid protection of bases A246, A274, A279, and A282 in the stem region of helix 11 in the 5' domain and moderately fast modifications of helix 44 bases A1433 and A1434 in the 3' minor domain. At a later time, enhancements occur with bases A181and A190 in helix 9, bases A325 and A327 in helix 13, and base C264 at the distal end of helix 11 in the 5' domain of 16S rRNA. The modifications that occur in the stem region of helix 11 are distant from the binding site of protein S20, as determined from the crystal structure. Simultaneous addition of protein S17 with S20 to the complex significantly alters the modifications caused by protein S20 in the stem region of helix 11 but does not alter the remaining modifications. Our results indicate that protein S20 is binding to at least two alternate 16S rRNA sites during the early assembly process.
核糖体蛋白 S20 是一种主要的结合蛋白，它连接了 30S 核糖体亚基中 16S 核糖体 RNA（rRNA）的 5' 结构域和 3' 小结构域。使用时间依赖性硫酸二甲酯修饰，我们已经确定，当它与 16S rRNA 结合时，蛋白 S20 导致快速保护 5' 结构域中螺旋 11 茎区的碱基 A246、A274、A279 和 A282，以及 3' 小结构域中螺旋 44 的碱基 A1433 和 A1434 中度快速修饰。在稍后的时间，增强发生在螺旋 9 的碱基 A181 和 A190、螺旋 13 的碱基 A325 和 A327 以及 16S rRNA 5' 结构域中螺旋 11 远端的碱基 C264。从晶体结构确定，螺旋 11 茎区发生的修饰与蛋白 S20 的结合位点相距甚远。同时向复合物中添加 S17 蛋白与 S20 蛋白显著改变了蛋白 S20 在螺旋 11 茎区引起的修饰，但不会改变其余的修饰。我们的结果表明，在早期组装过程中，蛋白 S20 至少结合了两个替代的 16S rRNA 位点。
