Bacteriophage P4 Vis protein is needed for prophage excision
Bacteriophage P4 Vis protein is needed for prophage excision
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DOI：
10.1016/j.virol.2004.01.016
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发表时间：
2004-04-25
期刊：
影响因子：
3.7
通讯作者：
Ghisotti, D
中科院分区：
文献类型：
--
作者：
Calì, S;Spoldi, E;Ghisotti, D
在感染宿主大肠杆菌后，卫星噬菌体P4可以通过在attP和attB位点之间的Int介导的位点特异性重组将其基因组整合到细菌染色体中。相反的事件，切除，可以自发发生或由一个重复感染的P2辅助噬菌体诱导。在这项工作中，我们证明了P4维斯基因的产物，P4晚期启动子P-LL和P-sid的调节剂，是原噬菌体切除所需的。这一结论得到以下证据的支持：（i）携带移码突变或vis基因缺失的P4突变体不能自发地或在P2噬菌体重叠感染时切除两者;（ii）从质粒诱导的P4原噬菌体切除中表达维斯蛋白;（iii）切除依赖于功能性整合酶（Int）蛋白，因此表明维斯参与切除复合物的形成，而不是在切除重组事件本身中;（iv）维斯蛋白在attP区域中位于int基因和attP核心区域之间的两个不同框（框I和框11）处结合P4 DNA，并引起结合DNA的弯曲。此外，我们通过引物延伸定位了int转录物的5'端，发现维斯的异位表达降低了其信号强度，表明维斯也参与了int启动子的负调控。(C)2004年爱思唯尔公司All rights reserved.
Upon infection of its host Escherichia coli, satellite bacteriophage P4 can integrate its genome into the bacterial chromosome by Int-mediated site-specific recombination between the attP and the attB sites. The opposite event, excision, may either occur spontaneously or be induced by a superinfecting P2 helper phage. In this work, we demonstrate that the product of the P4 vis gene, a regulator of the P4 late promoters P-LL and P-sid, is needed for prophage excision. This conclusion is supported by the following evidence: (i) P4 mutants carrying either a frameshift mutation or a deletion of the vis gene were unable to excise both spontaneously or upon P2 phage superinfection; (ii) expression of the Vis protein from a plasmid induced P4 prophage excision; (iii) excision depended on a functional integrase (Int) protein, thus suggesting that Vis is involved in the formation of the excision complex, rather than in the excision recombination event per se; (iv) Vis protein bound P4 DNA in the attP region at two distinct boxes (Box I and Box 11), located between the int gene and the attP core region, and caused bending of the bound DNA. Furthermore, we mapped by primer extension the 5' end of the int transcript and found that ectopic expression of Vis reduced its signal intensity, suggesting that Vis is also involved in negative regulation of the int promoter. (C) 2004 Elsevier Inc. All rights reserved.