DNA sequence analysis of spontaneous histidine mutations in a polA1 strain of Escherichia coli K12 suggests a specific role of the GTGG sequence
DNA sequence analysis of spontaneous histidine mutations in a polA1 strain of Escherichia coli K12 suggests a specific role of the GTGG sequence
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对大肠杆菌 K12 polA1 菌株中自发组氨酸突变的 DNA 序列分析表明 GTGG 序列的特定作用
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发表时间：
1990
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影响因子：
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通讯作者：
D. Savic
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作者：
M. Jankovic;T. Kostić;D. Savic
摘要在 DNA 序列水平上分析了缺乏 DNA 聚合酶 I 的大肠杆菌 K12 菌株中自发产生的组氨酸突变。我们筛选了大约 150000 个菌落并分离出 106 个组氨酸营养缺陷型。其中，98 个是不稳定的 hisC 突变；分析的 12 个代表性突变体显示是通过切除序列 5'-GCTGGCTGGCTGGCTG-3' 中的单个四联体重复而产生的。在其他位点的八个突变中，三个 hisA 缺失和一个 hisD 缺失是由于串联重复五聚体 (hisD) 或十聚体 (hisA) 错位而发生的。发现单个 hisA 点突变是错义突变。未分析覆盖 his 操纵子的两个扩展删除。我们无法通过测序识别 hisC 缺失。我们得出的结论是，polA1 是一种强模仿子，它通过重复 DNA 序列中的 Streisinger 型错配诱导大部分负移码和缺失类型的突变。最后，讨论了在所有缺失和移码附近发现的 5'-GTGG-3' 序列及其反向或直接互补序列的可能作用。
SummarySpontaneously arising histidine mutations in an Escherichia coli K12 strain deficient for DNA polymerase I were analysed at the DNA sequence level. We screened approximately 150000 colonies and isolated 106 histidine auxotrophs. Of these, 98 were unstable hisC mutations; 12 representative mutants analysed were shown to have arisen by the excision of a single quadruplet repeat in the sequence 5′-GCTGGCTGGCTGGCTG-3′. Of the eight mutations at other sites, three hisA deletions and one hisD deletion occurred as a consequence of misalignment of tandemly repeated pentamers (hisD) or decamers (hisA). A single hisA point mutation was found to be a missense mutation. Two extended deletions, covering the his operon were not analysed. We could not identify the hisC deletion by sequencing. We conclude that polA1 is a strong imitator that induces mutations mostly of the minus frameshift and deletion type by a Streisinger-type of mispairing in repetitive DNA sequences. Finally, the possible role of a 5′-GTGG-3′ sequence and its inverted or direct complements, which are found in the vicinity of all the deletions and frameshifts, is discussed.