Bacteria cell walls contain many repeating glycan structures, such as peptidoglycans, lipopolysaccharides, teichoic acids, and capsular polysaccharides. Their synthesis starts in the cytosol, and they are constructed from a glycan lipid carrier, undecaprenyl phosphate (C₅₅P), which is essential for cell growth and survival. The lipid derivative undecaprenol (C₅₅OH) is predominant in many Gram-positive bacteria but has not been detected in Gram-negative bacteria; its origin and role have thus remained unknown. Recently, a homologue of diacylglycerol kinase (DgkA) in Escherichia coli (E. coli) was demonstrated to be an undecaprenol kinase (UK) in the Gram-positive bacterium Streptococcus mutans (S. mutans). In this study, we found that S. mutans UK was not only an undecaprenol kinase but also a Mg-ADP-dependent undecaprenyl phosphate phosphatase (UpP), catalyzing the hydrolysis of C₅₅P to C₅₅OH and a free inorganic phosphate. Furthermore, the naturally undetectable C₅₅OH was observed in E. coli cells expressing S. mutans dgkA, supporting the phosphatase activity of UK/UpP in vivo. These two activities were indispensable to each other and utilized identical essential residues binding to their substrates, suggesting that both activities share the same active site and might involve a direct phosphoryl transfer mechanism. This study revealed a unique membrane enzyme displaying bifunctional activities determined by substrate binding and C₅₅OH production. The reciprocal conversion of C₅₅P and the undecaprenol pool efficiently regulate cell wall synthesis, especially in Gram-positive bacteria.

中文翻译：

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十一碳烯醇激酶的十一碳烯酸磷酸酶活性调节革兰氏阳性细菌中的脂质池。

细菌细胞壁包含许多重复的聚糖结构，例如肽聚糖，脂多糖，磷壁酸和荚膜多糖。它们的合成始于胞质溶胶，由聚糖脂质载体十一碳烯基磷酸酯（C ₅₅ P）构成，这对于细胞的生长和存活至关重要。在许多革兰氏阳性细菌中主要存在脂质衍生物十一碳烯醇（C ₅₅ OH），但在革兰氏阴性细菌中尚未发现；因此，其起源和作用仍然未知。最近，在大肠杆菌（E. coli）中，二酰基甘油激酶（DgkA）的同系物被证明是革兰氏阳性菌变形链球菌（Streptococcus mutans）中的十一碳烯醇激酶（UK）。变形链球菌（S. mutans）。在这项研究中，我们发现变形链球菌UK不仅是十一碳烯醇激酶，而且是依赖Mg-ADP的十一碳烯基磷酸磷酸酶（UpP），催化C ₅₅ P水解为C ₅₅ OH和游离的无机磷酸盐。此外，在表达变形链球菌dgkA的大肠杆菌细胞中观察到天然无法检测到的C ₅₅ OH ，从而支持UK / UpP的磷酸酶活性在体内。这两个活性是彼此必不可少的，并且利用了与它们的底物结合的相同必需残基，这表明这两个活性共享相同的活性位点，并且可能涉及直接的磷酸基转移机制。这项研究揭示了一种独特的膜酶，该酶表现出由底物结合和C ₅₅ OH产生决定的双功能活性。C ₅₅ P和十一碳烯醇库的倒数转换有效地调节细胞壁的合成，特别是在革兰氏阳性细菌中。