Substrate recognition by human RNase P: identification of small, model substrates for the enzyme.
Substrate recognition by human RNase P: identification of small, model substrates for the enzyme.
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人 RNase P 的底物识别：鉴定该酶的小型模型底物。
DOI：
10.1002/j.1460-2075.1995.tb06986.x
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发表时间：
1995
期刊：
影响因子：
--
通讯作者：
Altman,S
中科院分区：
文献类型：
--
作者：
Yuan,Y;Altman,S
来自HeLa细胞的RNase P可以在体外有效地切割tRNA前体分子，但不能切割潜在的底物，其中D、反密码子和tRNA部分的可变环和茎都已被去除。然而，后者的亚结构域已被单独去除的分子确实充当底物。我们在这里展示了仅包含5′前导序列、受体茎和tRNA结构域的T茎和环，以及在两个茎的连接处的tRNA序列中核苷酸7下游的一个核苷酸那么小的凸起的分子，隆突中核苷酸的同一性在确定切割效率和切割效率方面都是重要的。底物和/或酶-底物复合物的构象。我们还表明，人类酶定位适当的网站切割其基板的一部分，通过“测量”的螺旋长度的受体和T茎在模型和天然基板。
RNase P from HeLa cells can efficiently cleave tRNA precursor molecules in vitro but cannot cleave potential substrates from which the D, anticodon and variable loops and stems of the tRNA moiety have all been removed. However, molecules from which the latter subdomains have been removed individually do serve as substrates. We show here that molecules that contain only a 5′ leader sequence, the acceptor stem and the T stem and loop of the tRNA domain, and a bulge as small as one nucleotide downstream from nucleotide 7 in the tRNA sequence at the junction of the two stems, can serve as substrates for human RNase P. The identity of the nucleotide in the bulge is important in determining both the efficiency of the cleavage and the conformation of the substrate and/or the enzyme‐substrate complex. We also show that the human enzyme locates the appropriate site for cleavage of its substrates in part by ‘measuring’ the length of the helices in the acceptor and T stems in both model and natural substrates.