Greenleaf A L, Weeks J R, Voelker R A, Ohnishi S, Dickson B
Cell. 1980 Oct;21(3):785-92. doi: 10.1016/0092-8674(80)90441-9.
We previously described an alpha-amanitin-resistant mutant of D. melanogaster (AmaC4 or simply C4) with an altered, amanitin-resistant RNA polymerase II. We have now more fully characterized this mutant genetically and biochemically. We genetically mapped C4 to position 35.66 on the X chromosome and cytogenetically localized it to the polytene chromosome band interval 10C2-10D4. We then demonstrated that C4 is allelic to a previously known lethal-mutable locus I(1)L5 in this chromosomal region. Several known lethal alleles of L5 in fact affected the properties of RNA polymerase II in vitro. Following EMS mutagenesis of the C4-bearing chromosome we recovered new lethal L5 alleles, some of which were shown biochemically to have an altered amanitin-resistance polymerase II component. Furthermore, we induced mutants of C4 that had lost amanitin-resistance and showed that these mutants were also lethal alleles of L5. All the lethal alleles of L5 failed to completely complement each other genetically, and when analyzed biochemically their polymerase II displayed altered enzymatic properties. We conclude that C4 is an allele of the L5 locus and that this locus is most probably a structural gene for a subunit of RNA polymerase II. Some of the mutants at this locus display developmental abnormalities.
我们之前描述过一种黑腹果蝇的α-鹅膏蕈碱抗性突变体（AmaC4或简称为C4），其RNA聚合酶II发生了改变，具有鹅膏蕈碱抗性。我们现在已经从遗传学和生物化学角度对该突变体进行了更全面的表征。我们通过遗传学方法将C4定位到X染色体上的35.66位置，并通过细胞遗传学方法将其定位到多线染色体带区间10C2 - 10D4。然后我们证明C4与该染色体区域中一个先前已知的致死性可变位点I(1)L5等位。事实上，L5的几个已知致死等位基因在体外影响了RNA聚合酶II的特性。在用携带C4的染色体进行EMS诱变后，我们获得了新的致死性L5等位基因，其中一些经生物化学分析显示其具有改变的抗鹅膏蕈碱的聚合酶II成分。此外，我们诱导出了失去鹅膏蕈碱抗性的C4突变体，并表明这些突变体也是L5的致死等位基因。L5的所有致死等位基因在遗传上都不能完全相互互补，并且在进行生物化学分析时，它们的聚合酶II显示出改变的酶学特性。我们得出结论，C4是L5位点的一个等位基因，并且该位点很可能是RNA聚合酶II一个亚基的结构基因。该位点的一些突变体表现出发育异常。
