MOLECULAR-GENETICS OF A CHROMOSOMAL LOCUS INVOLVED IN COPPER TOLERANCE IN ESCHERICHIA-COLI K-12
MOLECULAR-GENETICS OF A CHROMOSOMAL LOCUS INVOLVED IN COPPER TOLERANCE IN ESCHERICHIA-COLI K-12
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DOI：
10.1111/j.1365-2958.1995.tb02286.x
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发表时间：
1995-03-01
影响因子：
3.6
通讯作者：
LEE, BTO
中科院分区：
文献类型：
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作者：
FONG, ST;CAMAKARIS, J;LEE, BTO
cutA 基因座可能与大肠杆菌的铜耐受性有关，其特征是导致铜敏感性的突变。用放射性 Cu-64(2+) 进行的铜积累测量显示，cutA 铜敏感突变细胞的铜积累增加，而当 cutA 突变以反式互补时，铜积累减少。使用 cutA 突变体与野生型染色体片段对部分铜耐受性的互补来绘制基因座。对 cotA 涉及的 3.2 kb DNA 区域进行了测序和分析，揭示了三个重要的开放阅读框，其中没有一个之前曾发表过。当用T7噬菌体启动子表达系统合成时，所有三个开放阅读框的产物被鉴定为约50kDa、24kDa和13kDa的多肽，与从DNA序列预测的大小一致。 50 kDa 和 24 kDa 多肽存在于细菌内膜中，13 kDa 多肽存在于细胞质部分。除了铜耐受性所需之外，cutA 还会影响对锌盐、镍盐、钴盐和镉盐的耐受水平。 cutA 与 lux 操纵子的转录融合显示出铜盐、锌盐、镍盐、钴盐以及较小程度的镉盐、锰盐和银盐的诱导作用。
The cutA locus, presumably involved in copper tolerance in Escherichia coli, was characterized by a mutation leading to copper sensitivity. Copper-accumulation measurements with radioactive Cu-64(2+) showed increased uptake by cutA copper-sensitive mutant cells, and reduced uptake when the cutA mutation was complemented in trans. The locus was mapped using complementation of the cutA mutant to partial copper tolerance with wild-type chromosomal fragments. The 3.2 kb DNA region involved in cotA was sequenced and analysed, revealing three significant open reading frames, none of which had been previously published. The products of all three open reading frames were identified, when synthesized with the T7 phage promoter expression system, as polypeptides of about 50 kDa, 24 kDa, and 13 kDa, consistent with the sizes predicted from the DNA sequences. The 50 kDa and 24 kDa polypeptides were found in the bacterial inner membrane, and the 13 kDa polypeptide with the cytoplasmic fraction. In addition to being required for copper tolerance, cutA affects tolerance levels to zinc, nickel, cobalt and cadmium salts. Transcriptional fusions of cutA with the lux operon showed induction by copper, zinc, nickel, cobalt and, to a lesser extent, cadmium, manganese and silver salts.