...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Journal of bacteriology >Mutants of Escherichia coli 'cryptic' for certain periplasmic enzymes: evidence for an alteration of the outer membrane.
【24h】

Mutants of Escherichia coli 'cryptic' for certain periplasmic enzymes: evidence for an alteration of the outer membrane.

机译：大肠埃希氏菌某些周质酶的突变体是“隐性的”：外膜发生改变的证据。

获取原文
   

获取外文期刊封面封底 >>

       
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

Mutants in which the expression of periplasmic enzymes by whole cells is reduced (termed "cryptic") are also found to show greatly reduced uptake of labeled adenosine 5'-monophosphate (5'-AMP), providing a rapid assay for crypticity. The crypticity of 3'- and 5'-nucleotidase has been examined as a function of substrate concentration. The Km for 3'- or 5'-AMP increases in the cryptic mutants when whole cells are used as the enzyme source. The Vmax is not altered. Electrophoretic analysis of protein prepared from cell envelopes showed that three cryptic mutants have a polypeptide absent from the outer membrane and a relatively high proportion of a polypeptide in the inner membrane. Analysis of the molar ratios of constituent sugars of the lipopolysaccharides showed no differences between three cryptic mutants and the parent strain. One cryptic mutant (3--41), however, has altered sensitivity to phage T4. By selection for phage resistance, derivatives of the cryptic mutants that are deoxycholate sensitive have been obtained. These mutants are no longer cryptic. We suggest that cryptic mutants have an altered outer membrane, with decreased permeability to 3'- and 5'-AMP, as a result of an altered polypeptide.
机译：还发现其中全细胞的周质酶表达降低的突变体（称为“隐性”）显示出大大降低了标记的5'-单磷酸腺苷（5'-AMP）的摄取，从而提供了一种隐秘性的快速测定法。已经检查了3'-和5'-核苷酸酶的隐秘性与底物浓度的关系。当将全细胞用作酶源时，隐性突变体中3'-或5'-AMP的Km增加。 Vmax不变。从细胞包膜制备的蛋白质的电泳分析表明，三个隐性突变体的外膜缺少一种多肽，而内膜中却有相对较高比例的多肽。分析脂多糖的组成糖的摩尔比表明，在三个隐性突变体和亲本菌株之间没有差异。但是，一个隐性突变体（3--41）改变了对噬菌体T4的敏感性。通过选择噬菌体抗性，获得了对脱氧胆酸盐敏感的隐蔽突变体的衍生物。这些突变体不再是神秘的。我们建议隐性突变体具有改变的外膜，由于改变的多肽而降低了对3'-和5'-AMP的渗透性。

著录项

相似文献

  • 外文文献
  • 中文文献
  • 专利
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号