REQUIREMENTS FOR CONJUGAL DNA-SYNTHESIS IN DONOR STRAIN DURING FLAC TRANSFER
REQUIREMENTS FOR CONJUGAL DNA-SYNTHESIS IN DONOR STRAIN DURING FLAC TRANSFER
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DOI：
10.1016/0022-2836(78)90191-2
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发表时间：
1978-01-01
影响因子：
5.6
通讯作者：
WILLETTS, N
中科院分区：
文献类型：
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作者：
KINGSMAN, A;WILLETTS, N
虽然利福平和大观霉素对敏感的[细菌]供体的Flac转移频率没有任何影响，但利福平而不是大观霉素阻止了dnaB供体和tdk受体之间的交配中测得的供体接合DNA合成。因此，这种合成可能需要一种非翻译的RNA，尽管即使在没有这种RNA的情况下也会发生转移。供体接合DNA合成被废除在dnaE供体，DNA聚合酶III是负责这一过程，再次，质粒DNA转移不受影响。缺乏F菌毛的Flac突变体既不产生供体接合DNA合成，也不产生质粒DNA转移，可能是因为它们不能接收交配信号来激活转移过程。traI和traM的产物也是供体接合DNA合成和质粒DNA的物理转移所必需的，可能参与共价闭合环状质粒DNA转化为开环形式，开环形式是独立的但通常同时进行的合成和转移步骤的底物。供体接合DNA合成发生在两个piliated traG和traN突变体，并在traD突变体的速度降低，虽然在任何情况下，有物理转移的质粒DNA。因此，这些基因产物是DNA转移到受体所必需的，此外，缺乏traD产物可能会阻碍DNA合成。基于这些结果，提出了在接合过程中处理DNA的方案。
Although neither rifampicin nor spectinomycin had any effect on the frequency of Flac transfer by a sensitive [bacterial] donor, rifampicin but not spectinomycin prevented donor conjugal DNA synthesis as measured in matings between a dnaB donor and a tdk recipient. An untranslated RNA species is therefore probably required for this synthesis, although transfer took place even in its absence. Donor conjugal DNA synthesis was abolished in a dnaE donor, showing that DNA polymerase III is responsible for this process; again, plasmid DNA transfer was not affected. Flac mutants lacking the F pilus gave neither donor conjugal DNA synthesis nor plasmid DNA transfer, probably because they could not receive a mating signal to activate the transfer process. The products of traI and traM were also required both for donor conjugal DNA synthesis and for physical transfer of plasmid DNA, probably being involved in the conversion of covalently closed circular plasmid DNA into the open circular form that is the substrate for the independent although normally simultaneous synthesis and transfer steps. Donor conjugal DNA synthesis took place at a normal rate in both piliated traG and traN mutants, and at a reduced rate in traD mutants, although in no case was there physical transfer of plasmid DNA. These gene products are therefore required for DNA transfer to the recipient, and in addition, the absence of the traD product may hinder DNA synthesis. Based upon these results, a scheme for the processing of DNA during conjugation is presented.