Mutations in the E. coli Rep helicase increase the amount of DNA per cell.
Mutations in the E. coli Rep helicase increase the amount of DNA per cell.
复制标题
大肠杆菌 Rep 解旋酶的突变会增加每个细胞的 DNA 量。
DOI：
10.1016/s0378-1097(03)00595-0
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发表时间：
2003
影响因子：
2.1
通讯作者：
Trun,Nancy
中科院分区：
文献类型：
--
作者：
Trun,Nancy
ThembrA4突变使人对樟脑产生抗性，出现严重的生长缺陷，每个细胞的染色体DNA数量增加了两倍。额外的DNA是以同步方式从CoriC复制的。含有mbrA4的细胞对X射线的抵抗力更强，这表明额外的DNA代表完整或接近完整的染色体。我在这里报道了mbrA4是DNA解旋酶前导链的一个不常见的等位基因，代表8个独立分离的等位基因Rep(MbrA)包含该基因的三个相同的变化：从−44位的G到A，从基因起始(+1)；蛋白石停在第142密码子；甘氨酸到丝氨酸在第414密码子(G414S)。我的数据表明，rep(MbrA4)不是零突变，第三个突变G414S是樟脑抗性所必需的，樟脑抗性是与每个细胞DNA含量增加相关的表型。我还表明，DNA含量的增加并不会导致染色体独立分离。
ThembrA4mutation confers camphor resistance, severe growth defects and up to a two-fold increase in the amount of chromosomal DNA per cell. The extra DNA is replicated fromoriCin a synchronous fashion. Cells containingmbrA4are more resistant to X-rays, indicating that the extra DNA represents complete or nearly complete chromosomes. I report here thatmbrA4is an unusual allele of the leading strand DNA helicase, Rep. Eight independently isolated alleles ofrep(mbrA)contain the same three changes in therepgene: a G to A at position −44 from the start of the mRNA (+1); an opal stop at codon 142; and a glycine to serine at codon 414 (G414S). My data indicate thatrep(mbrA4)is not a null mutation and that the third mutation, G414S, is necessary for camphor resistance, the phenotype associated with increased DNA content per cell. I also show that increase in DNA content does not lead to independently segregating chromosomes.