Department of Chemistry and Biochemistry and Molecular Biology Program, Lake Forest College, Lake Forest, USA.
Sci Rep. 2023 May 26;13(1):8551. doi: 10.1038/s41598-023-35632-4.
Tuberculosis (TB) is the second leading cause of death by a single infectious disease behind COVID-19. Despite a century of effort, the current TB vaccine does not effectively prevent pulmonary TB, promote herd immunity, or prevent transmission. Therefore, alternative approaches are needed. We seek to develop a cell therapy that produces an effective antibiotic in response to TB infection. D-cycloserine (D-CS) is a second-line antibiotic for TB that inhibits bacterial cell wall synthesis. We have determined D-CS to be the optimal candidate for anti-TB cell therapy due to its effectiveness against TB, relatively short biosynthetic pathway, and its low-resistance incidence. The first committed step towards D-CS synthesis is catalyzed by the L-serine-O-acetyltransferase (DcsE) which converts L-serine and acetyl-CoA to O-acetyl-L-serine (L-OAS). To test if the D-CS pathway could be an effective prophylaxis for TB, we endeavored to express functional DcsE in A549 cells as a human pulmonary model. We observed DcsE-FLAG-GFP expression using fluorescence microscopy. DcsE purified from A549 cells catalyzed the synthesis of L-OAS as observed by HPLC-MS. Therefore, human cells synthesize functional DcsE capable of converting L-serine and acetyl-CoA to L-OAS demonstrating the first step towards D-CS production in human cells.
结核病（TB）是仅次于 COVID-19 的由单一传染病导致的第二大致死原因。尽管已经努力了一个世纪，但目前的结核病疫苗并不能有效地预防肺结核，促进群体免疫，或阻止传播。因此，需要寻找替代方法。我们试图开发一种细胞疗法，该疗法可针对结核病感染产生有效的抗生素。D-环丝氨酸（D-CS）是一种二线抗结核抗生素，可抑制细菌细胞壁合成。我们已经确定 D-CS 是抗结核病细胞疗法的最佳候选药物，因为它对结核病有效，生物合成途径相对较短，而且耐药性发生率较低。D-CS 合成的第一步由 L-丝氨酸-O-乙酰转移酶（DcsE）催化，该酶将 L-丝氨酸和乙酰辅酶 A 转化为 O-乙酰-L-丝氨酸（L-OAS）。为了测试 D-CS 途径是否可作为结核病的有效预防措施，我们试图在 A549 细胞中表达功能性 DcsE 作为人类肺部模型。我们使用荧光显微镜观察 DcsE-FLAG-GFP 的表达。从 A549 细胞中纯化的 DcsE 通过 HPLC-MS 观察到 L-OAS 的合成。因此，人类细胞可合成功能性 DcsE，可将 L-丝氨酸和乙酰辅酶 A 转化为 L-OAS，这表明人类细胞中 D-CS 生产的第一步。
