Role of the Cell Wall Microenvironment in Expression of a Heterologous SpaP-S1 Fusion Protein by Streptococcus gordonii
Role of the Cell Wall Microenvironment in Expression of a Heterologous SpaP-S1 Fusion Protein by Streptococcus gordonii
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DOI：
10.1128/aem.02178-10
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发表时间：
2011-03-01
影响因子：
4.4
通讯作者：
Lee, Song F.
中科院分区：
文献类型：
--
作者：
Davis, Elisabeth;Kennedy, Dustin;Lee, Song F.
革兰氏阳性菌细胞壁微环境中的电荷密度被认为影响异源蛋白的表达。为了测试这一点，在活疫苗候选细菌戈登链球菌中研究了由变形链球菌的表面蛋白SpaP和百日咳毒素S1片段组成的SpaP-S1融合蛋白的表达。结果表明，亲株PM 14表达极低水平的SpaP-S1。通过比较，dlt突变株（其在dlt操纵子中具有阻止细胞壁脂磷壁酸的D-丙氨酰化的突变）和另一突变株（OB 219（pPM 14），其缺乏LPXTG主要表面蛋白SspA和SspB）表达比亲本更多的SpaP-S1。dlt突变体和OB 219（pPM 14）菌株的细胞表面都比PM 14带更多的负电荷，这表明带负电荷的细胞壁在SpaP-S1产量的增加中起作用。因此，Ca 2+，Mg 2+，和K+的加入，推测增加细胞壁的正电荷，导致SpaP-S1生产的减少，而碳酸氢盐的加入导致SpaP-S1生产的增加。SpaP-S1的产生水平可能与PrsA（一种肽基脯氨酰顺式/反式异构酶）的水平相关。PrsA的表达似乎是由细胞膜应激双组分调节系统LiaSR调节的。这些结果共同表明，细胞壁微环境的电荷密度可以调节异源SpaP-S1蛋白在S. gordonii，这种调节是由PrsA的水平介导的，其表达由LiaSR双组分调控系统调节。
The charge density in the cell wall microenvironment of Gram-positive bacteria is believed to influence the expression of heterologous proteins. To test this, the expression of a SpaP-S1 fusion protein, consisting of the surface protein SpaP of Streptococcus mutans and a pertussis toxin S1 fragment, was studied in the live vaccine candidate bacterium Streptococcus gordonii. Results showed that the parent strain PM14 expressed very low levels of SpaP-S1. By comparison, the dlt mutant strain, which has a mutation in the dlt operon preventing D-alanylation of the cell wall lipoteichoic acids, and another mutant strain, OB219(pPM14), which lacks the LPXTG major surface proteins SspA and SspB, expressed more SpaP-S1 than the parent. Both the dlt mutant and the OB219(pPM14) strain had a more negatively charged cell surface than PM14, suggesting that the negative charged cell wall played a role in the increase in SpaP-S1 production. Accordingly, the addition of Ca2+, Mg2+, and K+, presumably increasing the positive charge of the cell wall, led to a reduction in SpaP-S1 production, while the addition of bicarbonate resulted in an increase in SpaP-S1 production. The level of SpaP-S1 production could be correlated with the level of PrsA, a peptidyl-prolyl cis/trans isomerase, in the cells. PrsA expression appears to be regulated by the cell envelope stress two-component regulatory system LiaSR. The results collectively indicate that the charge density of the cell wall microenvironment can modulate heterologous SpaP-S1 protein expression in S. gordonii and that this modulation is mediated by the level of PrsA, whose expression is regulated by the LiaSR two-component regulatory system.