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首页> 外文期刊>Journal of bacteriology >Stabilization of the 3' one-third of Escherichia coli ribosomal protein S20 mRNA in mutants lacking polynucleotide phosphorylase.
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Stabilization of the 3' one-third of Escherichia coli ribosomal protein S20 mRNA in mutants lacking polynucleotide phosphorylase.

机译：缺乏多核苷酸磷酸化酶的突变体中大肠杆菌核糖体蛋白S20 mRNA 3'三分之一的稳定性。

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摘要

Mutations which largely inactivate polynucleotide phosphorylase and which render RNase II thermolabile exert two effects on the metabolism of the two nested mRNAs which encode ribosomal protein S20. (i) The lifetime of both mRNA species is extended 2.5-fold at 38 degrees C in a strain harboring both mutations. (ii) A relatively stable truncated fragment of these mRNAs accumulates to significant levels in strains lacking polynucleotide phosphorylase. The truncated RNA (Po RNA) is 147 to 148 residues long and is coterminal with the 3' ends of intact S20 mRNAs. Its 5' end appears to be generated by endonucleolytic cleavage to the 5' side of a G residue in the sequence AACCGAUC. The data are consistent with the hypothesis that S20 mRNAs can be degraded by alternative pathways. The normal pathway depends on functional polynucleotide phosphorylase and is concerted, since S20 mRNAs disappear without accumulation of detectable intermediates in the decay process. The slower alternative pathway is followed when polynucleotide phosphorylase is inactivated by mutation. This pathway is distinguished by segmental rather than concerted degradation of S20 mRNAs and involves at least one endonucleolytic cleavage. The 5' two-thirds of S20 mRNAs decays significantly more quickly than the 3' third in this latter mode of mRNA turnover.
机译：在很大程度上失活多核苷酸磷酸化酶并使RNase II不耐热的突变，对编码核糖体蛋白S20的两个嵌套mRNA的代谢产生两种影响。 （i）在携带两种突变的菌株中，两种mRNA的寿命在38摄氏度时延长2.5倍。 （ii）在缺少多核苷酸磷酸化酶的菌株中，这些mRNA的相对稳定的截短片段积累到显着水平。截短的RNA（Po RNA）长度为147至148个残基，与完整S20 mRNA的3'末端共末端。它的5'端似乎是通过内切核酸酶切割序列AACCGAUC的G残基的5'端而产生的。数据与S20 mRNA可以通过其他途径降解的假设一致。正常途径依赖于功能性多核苷酸磷酸化酶并且是一致的，因为S20 mRNA消失而在衰变过程中没有可检测的中间体积累。当通过突变使多核苷酸磷酸化酶失活时，遵循较慢的替代途径。该途径的特征在于S20 mRNA的分段降解而不是协同降解，并且涉及至少一个核酸内切裂解。在后者的mRNA更新模式中，S20 mRNA的5'三分之二的衰变比3'三分之一的衰变快得多。

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