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首页> 外文期刊>Applied Microbiology >Role of the Cell Wall Microenvironment in Expression of a Heterologous SpaP-S1 Fusion Protein by Streptococcus gordonii
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Role of the Cell Wall Microenvironment in Expression of a Heterologous SpaP-S1 Fusion Protein by Streptococcus gordonii

机译：细胞壁微环境在戈登链球菌表达异源SpaP-S1融合蛋白中的作用

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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 St r eptococcus 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 Ca~(2+), Mg~(2+), 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.
机译：据信革兰氏阳性细菌细胞壁微环境中的电荷密度会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，亲本菌株PM14表达的SpaP-S1水平非常低。相比之下，在dlt操纵子中具有突变的dlt突变株阻止了细胞壁脂蛋白酸的d-丙氨酸化，而另一个缺少LPXTG主要表面蛋白SspA和SspB的突变株OB219（pPM14）表达更多。 SpaP-S1比父级。 dlt突变体和OB219（pPM14）菌株均具有比PM14更带负电的细胞表面，这表明带负电的细胞壁在SpaP-S1产量增加中发挥了作用。因此，添加Ca〜（2 +），Mg〜（2+）和K〜（+）可能会增加细胞壁的正电荷，从而导致SpaP-S1产量降低，而添加碳酸氢盐导致SpaP-S1产量增加。 SpaP-S1产生的水平可能与细胞中肽基脯氨酰顺/反异构酶PrsA的水平相关。 PrsA表达似乎受细胞膜应力两成分调节系统LiaSR的调节。这些结果共同表明，细胞壁微环境的电荷密度可以调节戈登链霉菌中异源SpaP-S1蛋白的表达，并且这种调节是由PrsA的水平介导的，其表达受LiaSR两组分调节系统调节。

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