MECHANISM OF POSTSEGREGATIONAL KILLING BY THE HOK GENE-PRODUCT OF THE PARB SYSTEM OF PLASMID R1 AND ITS HOMOLOGY WITH THE RELF GENE-PRODUCT OF THE ESCHERICHIA-COLI RELB OPERON
MECHANISM OF POSTSEGREGATIONAL KILLING BY THE HOK GENE-PRODUCT OF THE PARB SYSTEM OF PLASMID R1 AND ITS HOMOLOGY WITH THE RELF GENE-PRODUCT OF THE ESCHERICHIA-COLI RELB OPERON
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DOI：
10.1002/j.1460-2075.1986.tb04459.x
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发表时间：
1986-08-01
期刊：
影响因子：
11.4
通讯作者：
VONMEYENBURG, K
中科院分区：
文献类型：
--
作者：
GERDES, K;BECH, FW;VONMEYENBURG, K
质粒R1的parB区编码两个基因hok和sok，这两个基因是parB发挥质粒稳定活性所必需的。hok基因编码一种有效的细胞杀伤因子，它受sok基因产物的调节，使得在细胞分裂过程中失去携带parB质粒的细胞被迅速杀死。与宿主细胞死亡同时，观察到形态学的特征性变化。在这里，我们表明，由hok基因编码的杀伤因子是一个52个氨基酸的膜相关多肽。位于大肠杆菌relB操纵子中的基因，称为relF，被证明与hok基因同源。relF基因编码51个氨基酸的多肽，其与hok基因产物具有40%的同源性。hok和relF基因产物的诱导过表达导致相同的现象：细胞膜电位的损失、呼吸停止、宿主细胞的死亡和细胞形态的变化。将parB区和relB基因克隆到不稳定遗传的oriC微型染色体中。parB区域也赋予oriC微型染色体高度的遗传稳定性，而relB操纵子（具有relF）则没有;因此后者似乎没有“稳定”其复制子（染色体）。relF基因的功能尚不清楚。
The parB region of plasmid R1 encodes two genes, hok and sok, which are required for the plasmid-stabilizing activity exerted by parB. The hok gene encodes a potent cell-killing factor, and it is regulated by the sok gene product such that cells losing a parB-carrying plasmid during cell division are rapidly killed. Coinciding with death of the host cell, a characteristic change in morphology is observed. Here we show that the killing factor encoded by the hok gene is a membrane-associated polypeptide of 52 amino acids. A gene located in the Escherichia coli relB operon, designated relF, is shown to be homologous to the hok gene. The relF gene codes for a polypeptide of 51 amino acids, which is 40% homologous to the hok gene product. Induced overexpression of the hok and relF gene products results in the same phenomena: loss of cell membrane potential, arrest of respiration, death of the host cell and change in cell morphology. The parB region and the relB genes were cloned into unstably inherited oriC minichromosomes. Whereas the parB region also conferred a high degree of genetic stability to an oriC minichromosome, the relB operon (with relF) did not; therefore the latter does not appear to ''stabilize'' its replicon (the chromosome). The function of the relF gene is not known.