Pyruvate forms the central node of carbon metabolism and promotes growth as an alternative carbon source during starvation. We recently revealed that LrgAB functions as a stationary phase pyruvate uptake system in Streptococcus mutans, the primary causative agent of human dental caries, but its underlying regulatory mechanisms are still not clearly understood. This study was aimed at further characterizing the regulation of LrgAB from a metabolomic perspective. We utilized a series of GFP quantification, growth kinetics, and biochemical assays. We disclosed that LrgAB is critical for pyruvate uptake especially during growth under low-glucose stress. Inactivation of the Pta-Ack pathway, responsible for the conversion of acetyl-CoA to acetate, completely inhibits stationary phase lrgAB induction and pyruvate uptake, and renders cells insensitive to external pyruvate as a signal. Inactivation of Pfl, responsible for the conversion of pyruvate to acetyl-CoA under anaerobic conditions, also affected stationary phase pyruvate uptake. This study explores the metabolic components of pyruvate uptake regulation through LrgAB, and highlights its potential as a metabolic stimulator, contributing to the resuscitation and survival of S. mutans cells during nutritional stress.

中文翻译：

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Pta-AckA途径调节变形链球菌中LrgAB介导的丙酮酸摄取。

丙酮酸形成碳代谢的中心节点，并在饥饿期间作为替代碳源促进生长。我们最近发现，LrgAB在变形链球菌（人类龋齿的主要病原体）中起着固定相丙酮酸摄取系统的作用，但其潜在的调控机制仍不清楚。这项研究旨在从代谢组学的角度进一步表征LrgAB的调控。我们利用了一系列的GFP定量，生长动力学和生化分析。我们公开了LrgAB对于丙酮酸摄取至关重要，尤其是在低葡萄糖胁迫下生长期间。Pta-Ack途径的失活，负责将乙酰辅酶A转化为乙酸盐，完全抑制了固定相lrgAB诱导和丙酮酸摄取，并使细胞对外部丙酮酸作为信号不敏感。Pfl的失活负责在厌氧条件下将丙酮酸转化为乙酰辅酶A，也影响了固定相丙酮酸的吸收。这项研究探索了通过LrgAB调节丙酮酸摄取的代谢成分，并突出了其作为代谢刺激剂的潜力，在营养压力下有助于变形链球菌细胞的复苏和存活。