CTXΦ-independent production of the RS1 satellite phage by Vibrio cholerae
CTXΦ-independent production of the RS1 satellite phage by Vibrio cholerae
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DOI：
10.1073/pnas.0237385100
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发表时间：
2003-02-04
影响因子：
11.1
通讯作者：
Nair, GB
中科院分区：
文献类型：
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作者：
Faruque, SM;Kamruzzaman, M;Nair, GB
霍乱弧菌的霍乱毒素基因由丝状噬菌体CTXPhi编码。染色体CTXPhi原噬菌体DNA通常被发现侧接有称为RS 1的相关遗传元件的拷贝，并且RS 1 DNA可以通过使用CTXPhi形态发生基因包装成丝状噬菌体颗粒（称为RS 1 Phi）。RS 1 Phi是进一步控制CTXPhi表达和传播的卫星噬菌体。在这里，我们描述了一个CTXPhi独立的机制，生产RS 1 Phi。鉴定了支持RS 1 Phi生产的非致突变环境霍乱弧菌菌株（55 V71）。然而，新感染的CTX阴性菌株不产生RS 1 Phi，表明另外的55 V71基因参与RS 1 Phi的产生。从55 V71的噬菌体制剂的核酸分析揭示了一个7.5 kb的单链DNA，其相应的复制形式被发现在质粒制剂。这种DNA可能对应于一种新的丝状噬菌体的基因组，我们将其命名为KSF-1 Phi。将KSF-1 Phi的复制型DNA克隆到pUC 18中，所得构建体pKSF-1.1支持CTX阴性霍乱弧菌菌株产生RS 1 Phi颗粒。以这种方式产生的RS 1+颗粒通过不依赖于CTXPhi受体（毒素共调节菌毛）的机制感染受体霍乱弧菌菌株。因此，KSF-1 Phi能够促进RS 1元件转移到不表达毒素共调节菌毛的菌株。鉴于RS 1 Phi可以增强CTXPhi颗粒的共产生，KSF-1 Phi介导的RS 1传播可能间接促进毒素基因在霍乱弧菌菌株中的传播。这项研究还表明，丝状真菌可以包装不同的DNA元件，因此可能在比以前认识到的更多基因的水平转移中发挥作用。
The cholera toxin genes of Vibrio cholerae are encoded by the filamentous phage, CTXPhi. Chromosomal CTXPhi prophage DNA is often found flanked by copies of a related genetic element designated RS1, and RS1 DNA can be packaged into filamentous phage particles (designated RS1Phi) by using the CTXPhi morphogenesis genes. RS1Phi is a satellite phage that further controls expression and dissemination of CTXPhi. Here we describe a CTXPhi-independent mechanism for production of RS1Phi. A nontoxigenic environmental V. cholerae strain (55V71) was identified that supports production of RS1Phi. However, newly infected CTX-negative strains did not produce RS1Phi, indicating that additional 55V71 genes were involved in production of RS1Phi. Analysis of nucleic acids from phage preparations of 55V71 revealed a 7.5-kb single-stranded DNA, whose corresponding replicative form was found in plasmid preparations. This DNA likely corresponds to the genome of a new filamentous phage, which we have designated KSF-1Phi. The replicative form DNA of KSF-1Phi was cloned into pUC18, and the resulting construct pKSF-1.1 supported the production of RS1Phi particles by CTX-negative V. cholerae strains. RS1+ particles produced in this way infect recipient V. cholerae strains by a mechanism that is independent of the CTXPhi receptor, the toxin-coregulated pilus. Thus, KSF-1Phi is capable of facilitating the transfer of the RS1 element to strains that do not express toxin coregulated pilus. Given that RS1Phi can enhance coproduction of CTXPhi particles, KSF-1Phi-mediated dissemination of RS1 may indirectly promote the spread of toxin genes among V. cholerae strains. This study also shows that filamentous phages can package diverse DNA elements and thus may play a role in horizontal transfer of more genes than previously appreciated.