Polarity suppression by the Q gene product of bacteriophage lambda.
Polarity suppression by the Q gene product of bacteriophage lambda.
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噬菌体 lambda 的 Q 基因产物的极性抑制。
DOI：
10.1016/0022-2836(82)90314-x
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发表时间：
1982
影响因子：
5.6
通讯作者：
I. Herskowitz
中科院分区：
文献类型：
--
作者：
D. Forbes;I. Herskowitz
λ噬菌体晚期基因受噬菌体Q蛋白的正调控。有人提出，Q通过充当转录的抗终止子来刺激晚期基因转录，允许6S转录物延伸到晚期基因中。我们已经研究了Q作为抗终止子的能力，通过分析溶原性菌株，其中bacterialgaloperon的方向与原噬菌体晚期基因相同。这种定向在携带λgt-C′原噬菌体的溶原菌中实现，该噬菌体具有包含噬菌体位点的区域的反转。在这种λgt-C′溶原菌中，半乳糖激酶（galK）产物的合成是由噬菌体Q蛋白诱导的。在半乳糖操纵子中携带极性突变（赭石和琥珀无义突变以及IS 1和IS 2插入元件）的菌株中，半乳糖激酶的表达同样被Q诱导。Q-依赖性极性减轻不需要噬菌体N蛋白、早期启动子或Q控制下的任何噬菌体蛋白，并且不需要原噬菌体DNA的复制。因此，Q蛋白似乎足以抑制极性，因此是早期基因转录抗终止子N蛋白的晚期基因类似物。
The late genes of bacteriophage λ are positively regulated by the phage Q protein. It has been proposed that Q stimulates late gene transcription by acting as an antiterminator of transcription, allowing extension of the 6 S transcript into the late genes. We have examined the ability of Q to act as an antiterminator by analysis of lysogenic strains in which the bacterialgaloperon is oriented in the same direction as the prophage late genes. This orientation is achieved in lysogens carrying aλgt-C′ prophage, which has an inversion of the region containing the phageattsite. In suchλgt-C′ lysogens, synthesis of thegalK product (galactokinase) is induced by the phage Q protein. Galactokinase expression is likewise induced by Q in strains carrying polar mutations in thegaloperon (ochreandambernonsense mutations and IS1 and IS2 insertion elements). Q-dependent relief of polarity does not require the phage N protein, early promoters, or any phage proteins under Q control and does not require replication of the prophage DNA. Q protein thus appears to be sufficient to suppress polarity and hence is a late gene analogue of the early gene transcription antiterminator, N protein.