Bactericidal activity of colicin V is mediated by an inner membrane protein, SdaC, of Escherichia coli
Bactericidal activity of colicin V is mediated by an inner membrane protein, SdaC, of Escherichia coli
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DOI：
10.1128/jb.187.6.1945-1950.2005
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发表时间：
2005-03-01
影响因子：
3.2
通讯作者：
Wu, LF
中科院分区：
文献类型：
--
作者：
Gérard, F;Pradel, N;Wu, LF
大肠菌素 V (CoIV) 是一种肽类抗生素，一旦从周质面进入内膜，就会通过破坏敏感细胞的膜电位来杀死敏感细胞。最近，我们构建了一种易位自杀探针RR-CoIV，它通过TAT途径易位到周质中，从而杀死宿主细胞。在本研究中，我们通过随机 Tn10 转座诱变获得了 RR-CoIV 抗性突变体。测序分析显示，该突变体在 sdaC（也称为 dcrA）基因中携带两个插入片段，该基因参与丝氨酸摄取，并且是 C1 噬菌体吸附所需的。在该突变体的细胞质和周质中均检测到 ColV 活性，表明 RR-CoIV 易位到周质中，但未能与内膜相互作用。 sdaC::Tn10 突变体仅对 CoIV 具有抗性，并且对大肠杆菌素 la、E3 和 A 保持敏感。最重要的是，当 CoIV 通过与 II 型整合膜蛋白 EtpM 融合而锚定到内膜的周质面时，sdaC::Tn10 突变体被杀死。综上所述，这些结果表明 SdaC/DcrA 蛋白可作为 CoIV 的特异性内膜受体。
Colicin V (CoIV) is a peptide antibiotic that kills sensitive cells by disrupting their membrane potential once it gains access to the inner membrane from the periplasmic face. Recently, we constructed a translocation suicide probe, RR-CoIV, that is translocated into the periplasm via the TAT pathway and thus kills the host cells. In this study, we obtained an RR-CoIV-resistant mutant by using random Tn10 transposition mutagenesis. Sequencing analysis revealed that the mutant carried a TWO insertion in the sdaC (also called dcrA) gene, which is involved in serine uptake and is required for C1 phage adsorption. ColV activity was detected both in the cytoplasm and in the periplasm of this mutant, indicating that RR-CoIV was translocated into the periplasm but failed to interact with the inner membrane. The sdaC::Tn10 mutant was resistant only to CoIV and remained sensitive to colicins la, E3, and A. Most importantly, the sdaC::Tn10 mutant was killed when CoIV was anchored to the periplasmic face of the inner membrane by fusion to EtpM, a type II integral membrane protein. Taken together, these results suggest that the SdaC/DcrA protein serves as a specific inner membrane receptor for CoIV.