Department of Biochemistry & Biophysics, Texas A&M University , College Station, Texas 77843, United States.
Department of Biochemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.
J Am Chem Soc. 2017 Jul 19;139(28):9463-9466. doi: 10.1021/jacs.7b04824. Epub 2017 Jul 3.
Bacterial capsular polysaccharides (CPS) are complex carbohydrate structures that play a role in the overall fitness of the organism. Campylobacter jejuni, known for being a major cause of bacterial gastroenteritis worldwide, produces a CPS with a unique O-methyl phosphoramidate (MeOPN) modification on specific sugar residues. The formation of P-N bonds in nature is relatively rare, and the pathway for the assembly of the phosphoramidate moiety in the CPS of C. jejuni is unknown. In this investigation we discovered that the initial transformation in the biosynthetic pathway for the MeOPN modification of the CPS involves the direct phosphorylation of the amide nitrogen of l-glutamine with ATP by the catalytic activity of Cj1418. The other two products are AMP and inorganic phosphate. The l-glutamine-phosphate product was characterized using P NMR spectroscopy and mass spectrometry. We suggest that this newly discovered enzyme be named l-glutamine kinase.
细菌荚膜多糖（CPS）是一种复杂的碳水化合物结构，在生物体的整体适应性中发挥作用。空肠弯曲菌是世界范围内细菌性肠胃炎的主要致病菌，其产生的 CPS 具有独特的 O-甲基膦酸酰胺（MeOPN）修饰特定糖残基。在自然界中形成 P-N 键相对较少，并且空肠弯曲菌 CPS 中膦酸酰胺部分的组装途径尚不清楚。在本研究中，我们发现 CPS 中 MeOPN 修饰生物合成途径中的初始转化涉及 Cj1418 的催化活性，用 ATP 直接磷酸化 l-谷氨酰胺的酰胺氮。其他两个产物是 AMP 和无机磷酸盐。使用 P NMR 光谱和质谱法对 l-谷氨酰胺-磷酸产物进行了表征。我们建议将这种新发现的酶命名为 l-谷氨酰胺激酶。
