Robert-Le Meur M, Portier C
Institut de Biologie Physico-Chimique, CNRS (URA1139), Paris, France.
Nucleic Acids Res. 1994 Feb 11;22(3):397-403. doi: 10.1093/nar/22.3.397.
Polynucleotide phosphorylase, a 3' to 5' processive exoribonuclease is post-transcriptionally autocontrolled and it was previously shown that this control is dependent on a 5' processing by RNase III. In this paper, the mechanism of regulation is analyzed by studying the properties of a pnp-lacZ translational gene fusion. It is shown that this message is stable, even when processed by RNase III, and that the degradation rate is directly linked to the intracellular concentration of polynucleotide phosphorylase or to the pnp-lacZ messenger translation rate. Mutations able to decrease the level of repression are all located in the ribosome loading site. Taken together, these results suggest that polynucleotide phosphorylase is able to recognize specifically the processed messenger and to prevent its translation, thus allowing degradation of the message.
多核苷酸磷酸化酶是一种从3'到5'的持续性外切核糖核酸酶，其表达在转录后受到自身调控，先前的研究表明这种调控依赖于核糖核酸酶III对5'端的加工。在本文中，通过研究pnp-lacZ翻译基因融合体的特性来分析其调控机制。结果表明，即使经过核糖核酸酶III的加工，该信使RNA仍然稳定，其降解速率与细胞内多核苷酸磷酸化酶的浓度或pnp-lacZ信使RNA的翻译速率直接相关。能够降低抑制水平的突变均位于核糖体装载位点。综上所述，这些结果表明多核苷酸磷酸化酶能够特异性识别经过加工的信使RNA并阻止其翻译，从而使信使RNA得以降解。
