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首页> 外文期刊>Journal of bacteriology >Defective transport and other phenotypes of a periplasmic 'leaky' mutant of Escherichia coli K-12.
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Defective transport and other phenotypes of a periplasmic 'leaky' mutant of Escherichia coli K-12.

机译：大肠杆菌K-12周质“泄漏”突变体的缺陷运输和其他表型。

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摘要

A mutant of Escherichia coli K-12 deficient in high-affinity leucine transport and related binding proteins was obtained by selecting for azaleucine resistance after bacteriophage Mu mutagenesis. We determined that the cause was a generalized loss of periplasmic binding proteins and a sharp decrease in the activity of transport systems requiring them. Other transport systems resistant to osmotic shock and present in membrane vesicles, were affected to a lesser degree or not at all. The mutation, designated lky::Mucts, was shown to be a pleiotropic envelope mutation, rendering the mutant sensitive to ionic and nonionic detergents, antibiotics, and ethylenediaminetetraacetic acid: the strain had also acquired tolerance to colicins E1, E2, and E3, while remaining normally sensitive to a variety of bacteriophages. An analysis of the lipopolysaccharide of parent and mutant strains revealed a twofold reduction in the neutral sugar content of the core oligosaccharide of the lky strain, but no change in sensitivities to phages which utilize lipopolysaccharide or outer membrane proteins for absorption. The lky::Mucts locus was mapped by transduction and found to be located near, or in, the tolPAB gene cluster linked to gal. Secondary mutations suppressing the detergent sensitivity of lky arose at a frequency of 10(-7), yielding a variety of new phenotypes. The lky::Mucts mutation did not give rise to obvious alterations in the gross morphology of the cell or in cell division.
机译：通过在噬菌体Mu诱变后选择氮杂亮氨酸抗性，获得了缺乏高亲和力亮氨酸转运和相关结合蛋白的大肠杆菌K-12突变体。我们确定原因是周质结合蛋白的普遍丧失以及需要它们的运输系统活性的急剧下降。存在于膜囊泡中的其他对渗透压冲击具有抵抗力的运输系统受到的影响较小或完全没有受到影响。该突变称为lky :: Mucts，显示为多效性包膜突变，使该突变株对离子和非离子去污剂，抗生素和乙二胺四乙酸敏感：该菌株还对大肠菌素E1，E2和E3具有耐受性，而其余通常对各种噬菌体敏感。对亲本和突变菌株的脂多糖的分析表明，lky菌株核心寡糖的中性糖含量降低了两倍，但对利用脂多糖或外膜蛋白进行吸收的噬菌体的敏感性没有变化。通过转导定位了lky :: Mucts基因座，发现其位于与gal连接的tolPAB基因簇附近或之中。二级突变以10（-7）的频率抑制了Lky Arose的去污剂敏感性，产生了许多新的表型。 lky :: Mucts突变并未引起细胞总体形态或细胞分裂的明显改变。

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