Durand Sylvain, Richard Graziella, Bisaglia Marco, Laalami Soumaya, Bontems François, Uzan Marc
Institut Jacques Monod, UMR7592 CNRS-Universités Paris 6 and Paris 7, 2 Place Jussieu, 75251 Paris Cedex 05, France.
Nucleic Acids Res. 2006;34(22):6549-60. doi: 10.1093/nar/gkl911. Epub 2006 Nov 27.
The T4 RegB endoribonuclease cleaves specifically in the middle of the -GGAG- sequence, leading to inactivation and degradation of early phage mRNAs. In vitro, RegB activity is very weak but can be enhanced 10- to 100-fold by the Escherichia coli ribosomal protein S1. Not all RNAs carrying the GGAG motif are cleaved by RegB, suggesting that additional information is required to obtain a complete RegB target site. In this work, we find that in the presence of S1, the RegB target site is an 11 nt long single-stranded RNA carrying the 100% conserved GGA triplet at the 5' end and a degenerate, A-rich, consensus sequence immediately downstream. Our data support the notion that RegB alone recognizes only the trinucleotide GGA, which it cleaves very inefficiently, and that stimulation of RegB activity by S1 depends on the nucleotide immediately 3' to -GGA-.
T4 RegB核糖核酸酶特异性切割-GGAG-序列的中间部分，导致早期噬菌体信使核糖核酸（mRNA）失活并降解。在体外，RegB活性非常弱，但可被大肠杆菌核糖体蛋白S1增强10至100倍。并非所有携带GGAG基序的RNA都能被RegB切割，这表明获得完整的RegB靶位点还需要其他信息。在这项研究中，我们发现，在存在S1的情况下，RegB靶位点是一个11个核苷酸长的单链RNA，其5'端携带100%保守的GGA三联体，紧接下游是一个简并的、富含A的共有序列。我们的数据支持这样的观点，即单独的RegB仅识别三核苷酸GGA，其切割效率非常低，并且S1对RegB活性的刺激取决于紧邻GGA 3'端的核苷酸。
