Straley S C, Bowmer W S
Infect Immun. 1986 Feb;51(2):445-54. doi: 10.1128/iai.51.2.445-454.1986.
Yersinia pestis, the causative agent of plague, has a virulence determinant called the low-Ca2+ response (Lcr+ phenotype) that confers on the bacterium Ca2+ dependence for growth at 37 degrees C and expression of V antigen. This virulence determinant is common to the three species of Yersinia and is mediated by Lcr plasmids (called pCD in Y. pestis). In this study, we generated insertions of Mu dI1(Ap lac) in pCD1 of Y. pestis KIM, screened for cells showing transcriptional regulation by Ca2+, and obtained inserts that define at least four pCD1 genes. Their patterns of transcription under different growth conditions closely paralleled the pattern of expression of the V antigen. We tested for expression of Lcr-specific yersinial outer membrane proteins (Yops) by the pCD1::Mu dI1(Ap lac) plasmids. Four of the inserts each eliminated expression of a different Yop; one of these Yops was unique to Y. pestis. Two of the insertions affecting Yops caused avirulence, and one caused strongly decreased virulence of Y. pestis in mice. These data indicate that Yops, like the V antigen, are virulence attributes regulated in the low-Ca2+ response.
鼠疫耶尔森氏菌是鼠疫的病原体，具有一种称为低钙应答（Lcr +表型）的毒力决定因素，该因素使细菌在37℃下生长以及表达V抗原时依赖钙离子。这种毒力决定因素在三种耶尔森氏菌中是共有的，并且由Lcr质粒（在鼠疫耶尔森氏菌中称为pCD）介导。在本研究中，我们在鼠疫耶尔森氏菌KIM的pCD1中产生了Mu dI1（Ap lac）插入，筛选出显示受钙离子转录调控的细胞，并获得了定义至少四个pCD1基因的插入片段。它们在不同生长条件下的转录模式与V抗原的表达模式密切平行。我们测试了pCD1::Mu dI1（Ap lac）质粒对Lcr特异性耶尔森氏菌外膜蛋白（Yops）的表达情况。其中四个插入片段分别消除了不同Yop的表达；这些Yops中有一个是鼠疫耶尔森氏菌特有的。影响Yops的两个插入片段导致无毒力，还有一个导致鼠疫耶尔森氏菌在小鼠中的毒力大幅下降。这些数据表明，Yops与V抗原一样，是在低钙应答中受到调控的毒力属性。
