RNA structure-dependent uncoupling of substrate recognition and cleavage by Escherichia coli ribonuclease III
RNA structure-dependent uncoupling of substrate recognition and cleavage by Escherichia coli ribonuclease III
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DOI：
10.1093/nar/gkg329
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发表时间：
2003-05-01
影响因子：
14.9
通讯作者：
Nicholson, AW
中科院分区：
文献类型：
--
作者：
Calin-Jageman, I;Nicholson, AW
核糖核酸酶III的成员是双链特异性内核核酸酶的超家族，参与了不同的RNA成熟和衰减途径。革兰氏阴性细菌大肠杆菌过程的核糖核酸酶III rRNA和mRNA前体，其催化作用可以通过控制mRNA翻译和稳定性来调节基因表达。已经提出，大肠杆菌RNase III可以通过结合RNA而不裂解磷酸化剂来以非催化方式起作用。但是，没有直接证据证明这种行动方式。我们在这里描述了一种源自T7噬菌体R1.1 RNase III底物的RNA，该RNA耐于大肠杆菌III的体外裂解，但保留了可比的结合亲和力。 R1.1 [Cl3b] RNA被RNase III识别，其方式与R1.1 RNA相同，这是两个底物中特定突变的相似抑制作用所揭示的。结构验证测定和MFOLD分析表明，R1.1 [CL3B] RNA具有凸起的螺旋卵线基序代替R1.1不对称的内环。两个凸起的存在是需要的。凸起螺旋式基序是一种“催化”抗抑制剂，它与识别抗抑制剂不同，抑制了RNase III结合。
Members of the ribonuclease III superfamily of double-strand-specific endoribonucleases participate in diverse RNA maturation and decay pathways. Ribonuclease III of the gram-negative bacterium Escherichia coli processes rRNA and mRNA precursors, and its catalytic action can regulate gene expression by controlling mRNA translation and stability. It has been proposed that E.coli RNase III can function in a non-catalytic manner, by binding RNA without cleaving phosphodiesters. However, there has been no direct evidence for this mode of action. We describe here an RNA, derived from the T7 phage R1.1 RNase III substrate, that is resistant to cleavage in vitro by E.coli RNase III but retains comparable binding affinity. R1.1[CL3B] RNA is recognized by RNase III in the same manner as R1.1 RNA, as revealed by the similar inhibitory effects of a specific mutation in both substrates. Structure-probing assays and Mfold analysis indicate that R1.1[CL3B] RNA possesses a bulge- helix-bulge motif in place of the R1.1 asymmetric internal loop. The presence of both bulges is required for uncoupling. The bulge-helix-bulge motif acts as a 'catalytic' antideterminant, which is distinct from recognition antideterminants, which inhibit RNase III binding.