Akins D R, Porcella S F, Popova T G, Shevchenko D, Baker S I, Li M, Norgard M V, Radolf J D
Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX 75235, USA.
Mol Microbiol. 1995 Nov;18(3):507-20. doi: 10.1111/j.1365-2958.1995.mmi_18030507.x.
Protein export signals from the low-passage 297 strain of Borrelia burgdorferi were cloned as fusions with an Escherichia coli alkaline phosphatase (PhoA) reporter lacking a signal sequence. One PhoA+ clone (BbK2.10-PhoA) was derived from a borrelial lipoprotein. Although the polypeptide encoded by the full-length bbk2.10 gene had 76% similarity and 56% identity to outer surface protein F (OspF) from B. burgdorferi strain N40, antibodies directed against recombinant forms of the two proteins revealed that they were not cross-reactive. The nucleotide sequences of bbk2.10 and ospF from the N40 and 297 strains, respectively, were determined to confirm that the N40 and 297 strains each contained both genes. Southern blot analysis revealed that bbk2.10 is a single-copy gene and that the B. burgdorferi strain 297 and N40 genomes appeared to contain one other gene more closely related to ospF than bbk2.10. It was particularly noteworthy that ospF, but not bbk2.10, was expressed in vitro while B. burgdorferi-infected mice generated antibodies reactive with both lipoproteins. To help confirm that the BbK2.10-reactive antibodies produced by the B. burgdorferi-infected mice were specific for that protein, a second gene, bbk2.11, which hybridized with the ospF probe was cloned; the corresponding polypeptide reacted strongly with OspF antisera but failed to react with BbK2.10-specific antisera. Taken together, these data demonstrate that BbK2.10, BbK2.11, and OspF comprise a B. burgdorferi lipoprotein family and that at least one member (BbK2.10) appears to be expressed only during infection.
将来自低传代297株伯氏疏螺旋体的蛋白质输出信号克隆为与缺乏信号序列的大肠杆菌碱性磷酸酶（PhoA）报告基因的融合体。一个PhoA+克隆（BbK2.10-PhoA）源自一种伯氏疏螺旋体脂蛋白。尽管全长bbk2.10基因编码的多肽与伯氏疏螺旋体N40株的外表面蛋白F（OspF）有76%的相似性和56%的同一性，但针对这两种蛋白质重组形式的抗体显示它们没有交叉反应性。分别测定了N40株和297株的bbk2.10和ospF的核苷酸序列，以确认N40株和297株均含有这两个基因。Southern印迹分析表明bbk2.10是单拷贝基因，并且伯氏疏螺旋体297株和N40株基因组似乎还含有另一个与ospF比与bbk2.10更密切相关的基因。特别值得注意的是，ospF在体外表达，而感染伯氏疏螺旋体的小鼠产生的抗体与两种脂蛋白都有反应，但bbk2.10在体外不表达。为了帮助确认感染伯氏疏螺旋体的小鼠产生的与BbK2.10反应的抗体对该蛋白具有特异性，克隆了第二个与ospF探针杂交的基因bbk2.11；相应的多肽与OspF抗血清强烈反应，但与BbK2.10特异性抗血清不反应。综上所述，这些数据表明BbK2.10、BbK2.11和OspF构成了一个伯氏疏螺旋体脂蛋白家族，并且至少有一个成员（BbK2.10）似乎仅在感染期间表达。
