Rohde N, Daum H, Biebricher C K
Max Planck Institute for Biophysical Chemistry, Göttingen, Germany.
J Mol Biol. 1995 Jun 16;249(4):754-62. doi: 10.1006/jmbi.1995.0334.
The mutant spectrum of an RNA species that is replicated by Q beta replicase, MNV-11, was investigated by retrotranscribing the RNA to DNA and cloning it into plasmids. The sequences of several cDNA clones of MNV-11 populations amplified by Q beta replicase under various conditions were determined and compared. A surprisingly broad mutant distribution was found: the consensus sequence never made up more than 40% of the total population and was accompanied by many mutants. Most mutants had several base exchanges, insertions and/or deletions; up to nine of the total 86 nucleotides were changed. The mutants found had replication rates comparable to that of the wild-type and were thus enriched in the population by selection forces. When the growth conditions were changed, the mutant distribution centre was shifted. The published consensus sequence of MNV-11 did not have the highest growth rate of the mutants, but was rather the best adapted to the various selection forces governing the growth phases the replicating RNA went through, i.e. it had found an optimal compromise between the rates of overall replication, enzyme binding and double strand formation.
通过将RNA逆转录为DNA并克隆到质粒中，研究了由Qβ复制酶复制的RNA物种MNV-11的突变谱。测定并比较了在各种条件下由Qβ复制酶扩增的MNV-11群体的几个cDNA克隆的序列。发现了一个惊人的广泛突变分布：共有序列在总群体中所占比例从未超过40%，并且伴随着许多突变体。大多数突变体有几个碱基交换、插入和/或缺失；在总共86个核苷酸中，多达9个发生了变化。所发现的突变体具有与野生型相当的复制速率，因此通过选择力在群体中富集。当生长条件改变时，突变分布中心发生了转移。已发表的MNV-11共有序列在突变体中没有最高的生长速率，而是最适应控制复制RNA所经历生长阶段的各种选择力，即它在整体复制速率、酶结合和双链形成速率之间找到了最佳折衷。
