CTX prophages in classical biotype Vibrio cholerae:: Functional phage genes but dysfunctional phage genomes
CTX prophages in classical biotype Vibrio cholerae:: Functional phage genes but dysfunctional phage genomes
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DOI：
10.1128/jb.182.24.6992-6998.2000
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发表时间：
2000-12-01
影响因子：
3.2
通讯作者：
Waldor, MK
中科院分区：
文献类型：
--
作者：
Davis, BM;Moyer, KE;Waldor, MK
CTX phi是一种丝状、溶原性噬菌体，其基因组编码霍乱毒素，霍乱毒素是霍乱弧菌产生的主要毒力因子。霍乱弧菌O1 El Tor和O139菌株中的CTX噬菌体存在于霍乱弧菌大染色体单个位点整合的遗传相关元件阵列中。o1el - Tor和O139菌株的噬菌体一般产生传染性的ctxphi。相比之下，V型霍乱经典菌株O1不产生CTX φ，尽管它们产生霍乱毒素，并且在两个位点含有整合的CTX噬菌体。我们确定了O1经典菌株中CTX噬菌体整合的第二个位点，并对经典噬菌体阵列进行了遗传和功能表征。经典前噬菌体的基因编码生产ctxphi所需的所有蛋白质的功能形式。经典的CTX前噬菌体要么是单独的前噬菌体，要么是两个截断融合的前噬菌体阵列，RSI是一种与CTX phi密切相关的遗传因子，在El - Tor菌株中经常与CTX前噬菌体穿插在一起，但在经典V，霍乱中未检测到RSI。我们的CTX phi生产模型预测，经典菌株中的CTX前噬菌体排列不会产生染色体外CTX DNA，因此不会产生病毒粒子。我们的实验结果证实了这一预测。因此，01株霍乱经典菌株不能产生CTX phi是由于经典噬菌体阵列结构的整体缺陷，而不是影响单个CTX噬菌体基因的突变。
CTX phi is a filamentous, lysogenic bacteriophage whose genome encodes cholera toxin, the primary virulence factor produced by Vibrio cholerae, CTX prophages in O1 El Tor and O139 strains of V. cholerae are found within arrays of genetically related elements integrated at a single locus within the V. cholerae large chromosome. The prophages of O1 El Tor and O139 strains generally yield infectious CTX phi. In contrast, O1 classical strains of V, cholerae do not produce CTX phi, although they produce cholera toxin and they contain CTX prophages integrated at two sites. We have identified the second site of CTX prophage integration in O1 classical strains and characterized the classical prophage arrays genetically and functionally. The genes of classical prophages encode functional forms of all of the proteins needed for production of CTX phi. Classical CTX prophages are present either as solitary prophages or as arrays of two truncated, fused prophages, RSI, a genetic element that is closely related to CTX phi and is often interspersed with CTX prophages in El Tor strains, was not detected in classical V,cholerae, Our model for CTX phi, production predicts that the CTX prophage arrangements in classical strains will not yield extrachromosomal CTX DNA and thus will not yield virions, and our experimental results confirm this prediction. Thus, failure of O1 classical strains of V, cholerae to produce CTX phi is due to overall deficiencies in the structures of the arrays of classical prophages, rather than to mutations affecting individual CTX prophage genes.