Proteome analysis of Streptococcus thermophilus grown in milk reveals pyruvate formate-lyase as the major upregulated protein
Proteome analysis of Streptococcus thermophilus grown in milk reveals pyruvate formate-lyase as the major upregulated protein
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DOI：
10.1128/aem.71.12.8597-8605.2005
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发表时间：
2005-12-01
影响因子：
4.4
通讯作者：
Rul, F
中科院分区：
文献类型：
--
作者：
Derzelle, S;Bolotin, A;Rul, F
利用蛋白质组学方法研究嗜热链球菌LMG 18311对牛奶的适应性。在M17培养基或牛奶中生长后进行胞质蛋白质的二维电泳。蛋白质组的一个主要变化涉及参与氨基酸供应的蛋白质，如肽酶PepX，以及参与氨基酸生物合成的几种酶。同时，我们观察到直接参与嘌呤合成的七种酶的合成上调，以及甲酰四氢叶酸（THF）合成酶和丝氨酸羟甲基转移酶，这两种酶负责合成供给嘌呤生物合成途径的化合物（分别为THF和甘氨酸）。分析还显示丙酮酸甲酸裂解酶（PFL）的合成大量增加，该酶将丙酮酸转化为乙酰辅酶A和甲酸。PFL在乳酸菌厌氧发酵过程中混合酸产物形成中的作用已被深入研究。然而，甲酸是通过形成叶酸衍生物的合成代谢途径的重要甲基供体。我们推测，PFL是参与嘌呤生物合成过程中的牛奶中的增长。我们发现，PFL的表达调控在转录水平和PFL的转录发生在牛奶中的指数生长期。补充牛奶中的甲酸或嘌呤碱基可以减少PFL的表达，抑制PFL的合成，并刺激S。嗜热菌这些结果显示了一种新的调节机制控制PFL的合成，并建议PFL作为合成代谢目的的甲酸供应商的未被认识的生理作用。
We investigated the adaptation to milk of Streptococcus thermophilus LMG18311 using a proteomic approach. Two-dimensional electrophoresis of cytosolic proteins were performed after growth in M17 medium or in milk. A major modification of the proteome concerned proteins involved in the supply of amino acids, like the peptidase PepX, and several enzymes involved in amino acid biosynthesis. In parallel, we observed the upregulation of the synthesis of seven enzymes directly involved in the synthesis of purines, as well as formyl-tetrahydrofolate (THF) synthetase and serine hydroxy-methyl transferase, two enzymes responsible for the synthesis of compounds (THF and glycine, respectively) feeding the purine biosynthetic pathway. The analysis also revealed a massive increase in the synthesis of pyruvate formate-lyase (PFL), the enzyme which converts pyruvate into acetyl coenzyme A and formate. PFL has been essentially studied for its role in mixed-acid product formation in lactic acid bacteria during anaerobic fermentation. However, formate is an important methyl group donor for anabolic pathway through the formation of folate derivates. We hypothesized that PFL was involved in purine biosynthesis during growth in milk. We showed that PFL expression was regulated at the transcriptional level and that pfl transcription occurred during the exponential growth phase in milk. The complementation of milk with formate or purine bases was shown to reduce pfl expression, to suppress PFL synthesis, and to stimulate growth of S. thermophilus. These results show a novel regulatory mechanism controlling the synthesis of PFL and suggest an unrecognized physiological role for PFL as a formate supplier for anabolic purposes.