Ramamoorthy R, Philipp M T
Department of Parasitology, Tulane Regional Primate Research Center, Tulane University Medical Center, Covington, Louisiana 70433, USA.
Infect Immun. 1998 Nov;66(11):5119-24. doi: 10.1128/IAI.66.11.5119-5124.1998.
In an earlier paper we described the transcriptionally regulated differential levels of expression of two lipoproteins of Borrelia burgdorferi, P35 and P7.5, during growth of the spirochetes in culture from logarithmic phase to stationary phase (K. J. Indest, R. Ramamoorthy, M. Solé, R. D. Gilmore, B. J. B. Johnson, and M. T. Philipp, Infect. Immun. 65:1165-1171, 1997). Here we further assess this phenomenon by investigating whether the expression of other antigens of B. burgdorferi, including some well-characterized ones, are also regulated in a growth-phase-dependent manner in vitro. These studies revealed 13 additional antigens, including OspC, BmpD, and GroEL, that were upregulated 2- to 66-fold and a 28-kDa protein that was downregulated 2- to 10-fold, during the interval between the logarithmic- and stationary-growth phases. Unlike with these in vitro-regulated proteins, the levels of expression of OspA, OspB, P72, flagellin, and BmpA remained unchanged throughout growth of the spirochetes in culture. Furthermore, ospAB, bmpAB, groEL, and fla all exhibited similar mRNA profiles, which is consistent with the constitutive expression of these genes. By contrast, the mRNA and protein profiles of ospC and bmpD indicated regulated expression of these genes. While bmpD exhibited a spike in mRNA expression in early stationary phase, ospC maintained a relatively higher level of mRNA throughout culture. These findings demonstrate that there are additional genes besides P7.5 and P35 whose regulated expression can be investigated in vitro and which may thus serve as models to facilitate the study of regulatory mechanisms in an organism that cycles between an arthropod and a vertebrate host.
在一篇早期论文中，我们描述了伯氏疏螺旋体的两种脂蛋白P35和P7.5在螺旋体从对数生长期到稳定期的培养过程中，其转录调控的差异表达水平（K. J. 因德斯特、R. 拉马穆尔蒂、M. 索莱、R. D. 吉尔摩、B. J. B. 约翰逊和M. T. 菲利普，《感染与免疫》65:1165 - 1171, 1997）。在此，我们通过研究伯氏疏螺旋体的其他抗原（包括一些特征明确的抗原）在体外是否也以生长阶段依赖的方式受到调控，进一步评估这一现象。这些研究揭示了另外13种抗原，包括OspC、BmpD和GroEL，在对数生长期和稳定生长期之间的间隔内上调了2至66倍，还有一种28 kDa的蛋白质下调了2至10倍。与这些体外调控的蛋白质不同，OspA、OspB、P72、鞭毛蛋白和BmpA的表达水平在螺旋体的整个培养过程中保持不变。此外，ospAB、bmpAB、groEL和fla均表现出相似的mRNA谱，这与这些基因的组成型表达一致。相比之下，ospC和bmpD的mRNA和蛋白质谱表明这些基因存在调控表达。虽然bmpD在稳定期早期mRNA表达出现峰值，但ospC在整个培养过程中维持相对较高水平的mRNA。这些发现表明，除了P7.5和P35之外，还有其他基因，其调控表达可在体外进行研究，因此可作为模型来促进对在节肢动物和脊椎动物宿主之间循环的生物体中调控机制的研究。
