Sergiev P V, Bogdanov A A, Dahlberg A E, Dontsova O
Department of Chemistry, Moscow State University, Moscow, 119899, Russia.
J Mol Biol. 2000 Jun 2;299(2):379-89. doi: 10.1006/jmbi.2000.3739.
The proximity of loop D of 5 S rRNA to two regions of 23 S rRNA, domain II involved in translocation and domain V involved in peptide bond formation, is known from previous cross-linking experiments. Here, we have used site-directed mutagenesis and chemical probing to further define these contacts and possible sites of communication between 5 S and 23 S rRNA. Three different mutants were constructed at position A960, a highly conserved nucleotide in domain II previously crosslinked to 5 S rRNA, and the mutant rRNAs were expressed from plasmids as homogeneous populations of ribosomes in Escherichia coli deficient in all seven chromosomal copies of the rRNA operon. Mutations A960U, A960G and, particularly, A960C caused structural rearrangements in the loop D of 5 S rRNA and in the peptidyltransferase region of domain V, as well as in the 960 loop itself. These observations support the proposal that loop D of 5 S rRNA participates in signal transmission between the ribosome centers responsible for peptide bond formation and translocation.
先前的交联实验已表明，5S rRNA的D环与23S rRNA的两个区域相邻，其中参与转位的结构域II和参与肽键形成的结构域V。在此，我们使用定点诱变和化学探针技术进一步确定这些接触点以及5S和23S rRNA之间可能的通讯位点。在A960位点构建了三种不同的突变体，A960是结构域II中一个高度保守的核苷酸，先前已与5S rRNA交联，突变的rRNA由质粒表达，作为缺乏rRNA操纵子所有七个染色体拷贝的大肠杆菌中核糖体的同质群体。突变A960U、A960G以及特别的A960C导致5S rRNA的D环、结构域V的肽基转移酶区域以及960环本身发生结构重排。这些观察结果支持了以下提议，即5S rRNA的D环参与负责肽键形成和转位的核糖体中心之间的信号传递。
