Replication and integration of a Vibrio cholerae cryptic plasmid linked to the CTX prophage
Replication and integration of a Vibrio cholerae cryptic plasmid linked to the CTX prophage
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DOI：
10.1046/j.1365-2958.1998.00889.x
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发表时间：
1998-06-01
影响因子：
3.6
通讯作者：
Waldor, MK
中科院分区：
文献类型：
--
作者：
Rubin, EJ;Lin, W;Waldor, MK
我们在我们测试的所有ctxAB(+)霍乱弧菌中发现了一个4.7kb的隐质粒。发现一株霍乱弧菌经典生物型菌株O395，该菌株含有高拷贝数的隐质粒。杂交分析表明，在所有霍乱弧菌产毒菌株中都存在与该质粒高度相关或相同的序列，但在所有缺乏毒素协同调节药丸和丝状CTX前体噬菌体基因的非产毒环境分离株中，该序列明显缺失。因此，我们将该隐藏质粒命名为毒素连锁的隐蔽质粒pTLC。测定了高拷贝数分离株pTLC的全序列。据预测，该质粒中最大的开放阅读框编码一种类似于大肠杆菌F-特异性丝状噬菌体的复制起始蛋白(PLL)的蛋白质。PTLC的核苷酸序列也有助于对其他霍乱弧菌中与pTLC同源的DNA进行结构鉴定。PTLC相关DNA在这些菌株中既以低拷贝数、共价闭合的环状DNA形式存在，又以单链复制、染色体整合的DNA形式存在。值得注意的是，pTLC的染色体整合形式与CTX原噬菌体相邻。PTLC的菌株分布、染色体定位和DNA序列表明，它可能是一种遗传元件，在CTX Phi的生物学中发挥一定的作用，可能促进其获得或复制。
We identified a 4.7 kb cryptic plasmid in all ctxAB(+) Vibrio cholerae strains we tested. An isolate of the V. cholerae classical biotype strain O395 that harbours the cryptic plasmid at high copy number was found. Hybridization analysis demonstrated that sequences highly related or identical to this plasmid exist in all toxigenic strains of V.cholerae but were notably absent in all non-toxigenic environmental isolates that lacked the genes for toxin-co-regulated pill and the filamentous CTX prophage. Accordingly, we have named the cryptic plasmid pTLC for toxin-linked cryptic. The complete nucleotide sequence of pTLC from the high-copy-number isolate was determined. The largest open reading frame in the plasmid is predicted to encode a protein similar to the replication initiation protein (pll) of Escherichia coli F-specific filamentous phages. The nucleotide sequence of pTLC also facilitated the structural characterization of the DNA homologous to pTLC in other strains of V.cholerae. pTLC-related DNA exists in these strains as both low-copy-number, covalently closed circular DNA and tandemly duplicated, chromosomally integrated DNA. Remarkably, the chromosomally integrated form of pTLC is adjacent to the CTX prophage. The strain distribution, chromosomal location and DNA sequence of pTLC suggests that it may be a genetic element that plays some role in the biology of CTX phi, perhaps facilitating either its acquisition or its replication.