Singer B S
Mol Gen Genet. 1984;193(1):104-9. doi: 10.1007/BF00327422.
We have previously demonstrated that the sequence 5'TGGCAA 3' located at codons 32-33 of the rIIB gene of bacteriophage T4 is a hotspot for transition mutations (Nelson et al. 1981). Here I report the properties of the same TGGCAA sequence introduced into the gene at codons 11-12. The sequence is highly mutable in both locations, suggesting that its high mutability is due to features of the TGGCAA itself and is not dependent on the immediate juxtaposition of additional external sequences. Within this sequence, at either location, only the transition at the central G:C pair frequently arises spontaneously or by 2-aminopurine or ethylmethane sulfonate mutagenesis. However, the 3' G:C pair, in addition, is highly mutable after nitrous acid or hydroxylamine treatment. This suggests that, within the TGGCAA sequence, there are two hotspots which are targeted by different mutagens.
我们之前已经证明，噬菌体T4的rIIB基因第32 - 33密码子处的5'TGGCAA 3'序列是转换突变的热点（尼尔森等人，1981年）。在此，我报告了在第11 - 12密码子处引入该基因的相同TGGCAA序列的特性。该序列在这两个位置都具有高度可变性，这表明其高度可变性是由于TGGCAA自身的特征，而不依赖于额外外部序列的直接并列。在该序列内，无论在哪个位置，只有中央G:C对的转换经常自发出现，或通过2 - 氨基嘌呤或甲基磺酸乙酯诱变产生。然而，此外，在亚硝酸或羟胺处理后，3' G:C对也具有高度可变性。这表明，在TGGCAA序列内，存在两个被不同诱变剂靶向的热点。
