Mekalanos J J, Sublett R D, Romig W R
J Bacteriol. 1979 Sep;139(3):859-65. doi: 10.1128/jb.139.3.859-865.1979.
We have mapped a regulatory site mediating the hyperproduction of cholera toxin in mutants of Vibrio cholerae strain 569B. Mutations in this locus, called htx, result in the hypertoxinogenic phenotype, as measured by the ganglioside filter assay and immunoradial diffusion. Transposon-facilitated recombination was used to construct improved genetic donors in 569B parental and hypertoxinogenic mutant strains. Subsequent mapping by conjugation indicated that the htx locus was closely linked to the rif, str, and ilv loci of V. cholerae. Analysis of recombinants from these crosses suggested the following gene order: thy str htx rif ilv arg. The close genetic linkage of htx to rif (as high as 98%) resulted in a high comutation frequency of these two loci by nitrosoguanidine mutagenesis. Transfer of the htx mutant locus from a hypertoxinogenic donor to several unrelated Tox+ strains of V. cholerae caused a detectable elevation of toxin production in the recipients. These results suggest that toxin production in diverse strains of V. cholerae is controlled by a common regulatory mechanism in which the htx gene product plays a significant role.
我们已定位到一个调控位点，该位点介导霍乱弧菌569B菌株突变体中霍乱毒素的过量产生。通过神经节苷脂滤膜测定法和免疫放射扩散法测定，这个名为htx的基因座发生突变会导致超毒素产生表型。利用转座子促进的重组在569B亲本菌株和超毒素产生突变体菌株中构建了改良的基因供体。随后通过接合进行的定位表明，htx基因座与霍乱弧菌的rif、str和ilv基因座紧密连锁。对这些杂交产生的重组体的分析表明基因顺序如下：thy str htx rif ilv arg。htx与rif的紧密遗传连锁（高达98%）导致这两个基因座通过亚硝基胍诱变具有很高的共突变频率。将htx突变基因座从超毒素产生供体转移到几种不相关的霍乱弧菌Tox+菌株中，导致受体菌株中毒素产生明显升高。这些结果表明，不同霍乱弧菌菌株中的毒素产生受一种共同调控机制控制，其中htx基因产物起重要作用。
