Perrotta A T, Been M D
Department of Biochemistry, Duke University Medical Center, Durham, NC 27710.
Nucleic Acids Res. 1993 Aug 25;21(17):3959-65. doi: 10.1093/nar/21.17.3959.
Three models for the secondary structure of the hepatitis delta virus (HDV) antigenomic self-cleaving RNA element were tested by site-directed mutagenesis. Two models in which bases 5' to the cleavage site are paired with sequence at the 3' end of the element were both inconsistent with the data from the mutagenesis. Specifically, mutations in the 3' sequence which decrease self-cleavage activity could not be compensated by base changes in the 5' sequence as predicted by these models. The evidence was consistent with a third model in which the 3' end pairs with a portion of a loop within the ribozyme sequence to generate a pseudoknot structure. This same pairing was also required to generate higher rates of cleavage in trans with a 15-mer ribozyme, thus ruling out a proposed hammerhead-like 'axehead' model for the HDV ribozyme.
通过定点诱变对丁型肝炎病毒（HDV）反基因组自我切割RNA元件二级结构的三种模型进行了测试。两种模型中，切割位点5'端的碱基与元件3'端的序列配对，这两种模型均与诱变数据不一致。具体而言，3'序列中降低自我切割活性的突变无法如这些模型所预测的那样通过5'序列中的碱基变化得到补偿。证据与第三种模型一致，即3'端与核酶序列内一个环的一部分配对以产生假结结构。在与一个15聚体核酶进行反式切割时，产生更高切割速率也需要这种相同的配对，从而排除了针对HDV核酶提出的类似锤头状的“斧状头”模型。
