Steinberg S, Cedergren R
Département de Biochimie, Université de Montréal, Québec, Canada.
RNA. 1995 Nov;1(9):886-91.
Even though the evolutionary conservation of the cloverleaf model is strongly suggestive of powerful constraints on the secondary structure of functional tRNAs, some mitochondrial tRNAs cannot be folded into this form. From the optimal base pairing pattern of these recalcitrant tRNAs, structural correlations between the length of the anticodon stem and the lengths of connector regions between the two helical domains, formed by the coaxial stacking of the anticodon and D-stems and the acceptor and T-stems, have been derived and used to scan the tRNA and tRNA gene database. We show here that some cytosolic tRNA gene sequences that are compatible with the cloverleaf model can also be folded into patterns proposed for the unusual mitochondrial tRNAs. Furthermore, the ability to be folded into these atypical structures correlates in the mature RNA sequences with the presence of dimethylguanosine, whose role may be to prevent the unusual mitochondrial tRNA pattern folding.
尽管三叶草模型在进化上的保守性强烈暗示了对功能性tRNA二级结构的强大限制，但一些线粒体tRNA无法折叠成这种形式。从这些难处理的tRNA的最佳碱基配对模式中，已经得出了反密码子茎的长度与由反密码子茎和D茎以及受体茎和T茎的同轴堆积形成的两个螺旋结构域之间的连接区长度之间的结构相关性，并用于扫描tRNA和tRNA基因数据库。我们在此表明，一些与三叶草模型兼容的胞质tRNA基因序列也可以折叠成针对异常线粒体tRNA提出的模式。此外，在成熟RNA序列中，折叠成这些非典型结构的能力与二甲基鸟苷的存在相关，二甲基鸟苷的作用可能是防止异常线粒体tRNA模式的折叠。
