Murphy J R, Skiver J, McBride G
J Virol. 1976 Apr;18(1):235-44. doi: 10.1128/JVI.18.1.235-244.1976.
We have isolated and partially characterized a beta-phage mutant lysogen of Corynebacterium diphtheriae, C7(betatoxct1+), which is partially insensitive to iron inhibition of diphtheria toxin production. tox expression by C7(betatoxct1+) was found to be partially constitutive. In the presence of concentrations of iron that almost completely inhibit the expression of diphtheria toxin by the wild type, C7(beta), the level of toxin production by C7(betatoxct1+) was found to be at least 25 times that of the parent. The purified tox gene product of C7(betatoxct1+) was immunologically and electrophoretically identical to, and equally as toxic as, diphtheria toxin purified from C7(beta). In addition, the partial N-terminal amino acid sequence was found to be identical to diphtheria toxin. This data strongly suggests that the mutation allowing for the constitutive expression of tox in C7(betatoxct1+) is outside of the structural gene. Furthermore, the constitutive expression of diphtheria toxin was found to be cis dominant in the double lysogen C7(betacrm45+/betatoxct1+). The data presented is consistent with the existence of a tox operator locus.
我们已经分离并部分鉴定了一株白喉棒状杆菌的β噬菌体突变溶原菌C7(betatoxct1+)，它对铁抑制白喉毒素产生具有部分抗性。发现C7(betatoxct1+)的tox表达部分呈组成型。在几乎完全抑制野生型C7(β)产生白喉毒素的铁浓度下，C7(betatoxct1+)产生的毒素水平至少是亲本的25倍。C7(betatoxct1+)纯化的tox基因产物在免疫学和电泳上与从C7(β)纯化的白喉毒素相同，毒性也相同。此外，发现其部分N端氨基酸序列与白喉毒素相同。这些数据强烈表明，允许C7(betatoxct1+)中tox组成型表达的突变位于结构基因之外。此外，发现在双溶原菌C7(betacrm45+/betatoxct1+)中，白喉毒素的组成型表达是顺式显性的。所呈现的数据与tox操纵基因位点的存在一致。
