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首页> 外文期刊>Infection and immunity >Pyruvate Formate Lyase Is Required for Pneumococcal Fermentative Metabolism and Virulence
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Pyruvate Formate Lyase Is Required for Pneumococcal Fermentative Metabolism and Virulence

机译：丙酮酸甲酸酯裂解酶是肺炎球菌发酵代谢和毒力所必需的

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Knowledge of the in vivo physiology and metabolism of Streptococcus pneumoniae is limited, even though pneumococci rely on efficient acquisition and metabolism of the host nutrients for growth and survival. Because the nutrient-limited, hypoxic host tissues favor mixed-acid fermentation, we studied the role of the pneumococcal pyruvate formate lyase (PFL), a key enzyme in mixed-acid fermentation, which is activated posttranslationally by PFL-activating enzyme (PFL-AE). Mutations were introduced to two putative pfl genes, SPD0235 and SPD0420, and two putative pflA genes, SPD0229 and SPD1774. End-product analysis showed that there was no formate, the main end product of the reaction catalyzed by PFL, produced by mutants defective in SPD0420 and SPD1774, indicating that SPD0420 codes for PFL and SPD1774 for putative PFL-AE. Expression of SPD0420 was elevated in galactose-containing medium in anaerobiosis compared to growth in glucose, and the mutation of SPD0420 resulted in the upregulation of fba and pyk, encoding, respectively, fructose 1,6-bisphosphate aldolase and pyruvate kinase, under the same conditions. In addition, an altered fatty acid composition was detected in SPD0420 and SPD1774 mutants. Mice infected intranasally with the SPD0420 and SPD1774 mutants survived significantly longer than the wild type-infected cohort, and bacteremia developed later in the mutant cohort than in the wild type-infected group. Furthermore, the numbers of CFU of the SPD0420 mutant were lower in the nasopharynx and the lungs after intranasal infection, and fewer numbers of mutant CFU than of wild-type CFU were recovered from blood specimens after intravenous infection. The results demonstrate that there is a direct link between pneumococcal fermentative metabolism and virulence.
机译：尽管肺炎球菌依赖于宿主营养素的有效获取和代谢来生长和存活，但对肺炎链球菌的体内生理和代谢的知识仍然有限。由于营养有限的低氧宿主组织有利于混合酸发酵，因此我们研究了肺炎球菌丙酮酸甲酸裂解酶（PFL）（混合酸发酵中的关键酶）的作用，该酶在PFL活化酶（PFL- AE）。将突变引入两个假定的 pfl 基因SPD0235和SPD0420，以及两个假定的 pfl A 基因SPD0229和SPD1774。终产物分析表明，没有SPNT0420和SPD1774缺陷的突变体产生的甲酸盐（PFL催化的反应的主要终产物），表明SPD0420编码PFL，而SPD1774编码假定的PFL-AE。与葡萄糖的生长相比，厌氧菌在含半乳糖的培养基中SPD0420的表达升高，并且SPD0420的突变导致分别编码的 fba 和 pyk 上调。果糖1,6-二磷酸醛缩酶和丙酮酸激酶，在相同条件下。此外，在SPD0420和SPD1774突变体中检测到脂肪酸组成发生了变化。经鼻内感染SPD0420和SPD1774突变体的小鼠存活时间明显长于野生型感染人群，并且菌血症在突变人群中的发展要晚于野生型感染人群。此外，鼻内感染后，鼻咽和肺中SPD0420突变体的CFU数量较少，静脉感染后从血液标本中回收的突变体CFU数量比野生型CFU少。结果表明，肺炎球菌发酵代谢与毒力之间存在直接联系。

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