Thill G, Vasseur M, Tanner N K
GENSET, Paris, France.
Biochemistry. 1993 Apr 27;32(16):4254-62. doi: 10.1021/bi00067a013.
The hepatitis delta virus (HDV) is a subviral RNA that contains a self-cleaving activity that is similar to the ribozyme activity found in certain plant pathogens. However, the sequences surrounding the cleavage site are unrelated to the hammerhead or hairpin ribozyme motifs, and it is considered to be a distinct ribozyme type. We made site-specific changes within two regions of the smallest contiguous HDV sequence that has optimal activity and kinetically analyzed the data at different temperatures to determine the potential roles of the residues. We distinguish between those changes that affect the rate of catalysis and those that promote the formation of inactive structures. We find that nucleotides +45 to +72 downstream from the cleavage site, which can form a hairpin structure, are dispensable for catalytic activity but that they enhance the cleavage efficiency. Nucleotides +17 to +19 and +28 to +30 form Watson and Crick base pairs that are important for activity, but the actual sequence is not critical. In contrast, the nucleotides between +21 and +26 are important for activity, and they may be involved in significant tertiary interactions.
丁型肝炎病毒（HDV）是一种亚病毒RNA，具有自我切割活性，这与某些植物病原体中发现的核酶活性相似。然而，切割位点周围的序列与锤头状或发夹状核酶基序无关，被认为是一种独特的核酶类型。我们在具有最佳活性的最小连续HDV序列的两个区域内进行了位点特异性改变，并在不同温度下对数据进行动力学分析，以确定这些残基的潜在作用。我们区分了那些影响催化速率的变化和那些促进无活性结构形成的变化。我们发现，切割位点下游的核苷酸+45至+72可形成发夹结构，其对催化活性并非必需，但可提高切割效率。核苷酸+17至+19和+28至+30形成对活性很重要的沃森和克里克碱基对，但实际序列并不关键。相比之下，+21至+26之间的核苷酸对活性很重要，它们可能参与显著的三级相互作用。
