GENETIC-ANALYSIS OF AN MDR-LIKE EXPORT SYSTEM - THE SECRETION OF COLICIN-V
GENETIC-ANALYSIS OF AN MDR-LIKE EXPORT SYSTEM - THE SECRETION OF COLICIN-V
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DOI：
10.1002/j.1460-2075.1990.tb07606.x
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发表时间：
1990-12-01
期刊：
影响因子：
11.4
通讯作者：
KOLTER, R
中科院分区：
文献类型：
--
作者：
GILSON, L;MAHANTY, HK;KOLTER, R
抗菌毒素大肠杆菌素V的细胞外分泌是通过信号序列独立的过程介导的，该过程需要两个连锁基因的产物：cvaA和cvaB。cvaB的核苷酸序列显示，其产物是蛋白质亚家族的成员，参与在真核生物和原核生物中发现的多种分子的输出。这组蛋白质，这里称为“MDR样”亚家族，其特征在于存在疏水区，随后是高度保守的ATP结合折叠。通过构建大肠杆菌素V的结构基因cvaC和碱性磷酸酶的基因phoA之间的融合，缺乏其信号序列，它被确定，在cvaC的N-末端的39个密码子包含的结构信息，允许CvaC-PhoA融合蛋白，以有效地跨质膜的大肠杆菌在CvaA/CvaB依赖的方式易位。该结果与产生输出缺陷型大肠杆菌素V的cvaC基因中的点突变的位置一致。在CvaC的N-末端存在输出信号与溶血素的输出信号的所观察到的C-末端位置形成对比，溶血素也利用MDR样蛋白进行其分泌。还发现大肠杆菌素V输出系统的CvaA组分显示与溶血素输出中涉及的另一组分HlyD的氨基酸序列相似性。第二个组件在这些系统中的作用和MDR样亚家族的其他成员也将有相应的第二个组件的可能性进行了讨论。大肠杆菌素V和溶血素细胞外分泌中使用的第三种成分是E.大肠杆菌宿主外膜蛋白TolC。
The extracellular secretion of the antibacterial toxin colicin V is mediated via a signal sequence independent process which requires the products of two linked genes: cvaA and cvaB. The nucleotide sequence of cvaB reveals that its product is a member of a subfamily of proteins, involved in the export of diverse molecules, found in both eukaryotes and prokaryotes. This group of proteins, here referred to as the ''MDR-like'' subfamily, is characterized by the presence of a hydrophobic region followed by a highly conserved ATP binding fold. By constructing fusions between the structural gene for colicin V, cvaC, and a gene for akaline phosphatase, phoA, lacking its signal sequence, it was determined that 39 codons in the N-terminus of cvaC contained the structural information to allow CvaC-PhoA fusion proteins to be efficiently translocated across the plasma membrane of Escherichia coli in a CvaA/CvaB dependent fashion. This result is consistent with the location of point mutations in the cvaC gene which yielded export deficient colicin V. The presence of the export signal at the N-terminus of CvaC contrasts with the observed C-terminal location of the export signal for hemolysin, which also utilizes an MDR-like protein for its secretion. It was also found that the CvaA component of the colicin V export system shows amino acid sequence similarities with another component involved in hemolysin export, HlyD. The role of the second component in these systems and the possibility that other members of the MDR-like subfamily will also have corresponding second components are discussed. A third component used in both colicin V and hemolysin extracellular secretion is the E. coli host outer membrane protein, TolC.