Sulfolipid-1 (SL-1) is a lipid that is abundantly found in the cell wall of Mycobacterium tuberculosis (Mtb). MtbFadD23 is crucial in the SL-1 synthesis pathway. Previously, 5′-O-[N-(11-phenoxyundecanoyl)sulfamoyl]adenosine (PhU-AMS) has been shown to be a general inhibitor of fatty-acid-adenylating enzymes (FadDs) in Mtb. However, the fatty acyl-AMP ligase (FAAL) class of FadDs, which includes MtbFadD23, appears to be functionally nonredundant in the production of multiple fatty acids. In this study, the ability of PhU-AMS to bind to MtbFadD23 was examined under in vitro conditions. The crystal structure of the MtbFadD23–PhU-AMS complex was determined at a resolution of 2.64 Å. Novel features were identified by structural analysis and comparison. Although PhU-AMS could bind to MtbFadD23, it did not inhibit the FAAL adenylation activity of MtbFadD23. However, PhU-AMS improved the main T_m value in a differential scanning fluorimetry assay, and a structural comparison of MtbFadD23–PhU-AMS with FadD32 and PA1221 suggested that PhU-AMS blocks the loading of the acyl chain onto Pks2. This study sheds light on the structure-based design of specific inhibitors of MtbFadD23 and general inhibitors of FAALs.

中文翻译：

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开发针对结核分枝杆菌 FadD23 的潜在抑制剂的结构基础

Sulfolipid-1 (SL-1) 是一种在结核分枝杆菌( Mtb )细胞壁中大量存在的脂质。Mtb FadD23 在 SL-1 合成途径中至关重要。此前，5'- O- [ N- (11-苯氧基十一烷酰基)氨磺酰基]腺苷 (PhU-AMS) 已被证明是Mtb中脂肪酸腺苷酸酶 (FadDs) 的通用抑制剂。然而，脂肪酰基-AMP 连接酶 (FAAL) 类 FadD（包括Mtb FadD23）在多种脂肪酸的生产中似乎在功能上不冗余。在本研究中，在体外条件下检查了PhU-AMS 与Mtb FadD23结合的能力。Mtb FadD23-PhU-AMS 复合物的晶体结构以 2.64 Å 的分辨率测定。通过结构分析和比较确定了新特征。尽管PhU-AMS可以与Mtb FadD23结合，但它并不能抑制Mtb FadD23的FAAL腺苷酸化活性。然而，PhU-AMS 改善了差示扫描荧光测定中的主要T _{m值，并且}Mtb FadD23–PhU-AMS 与 FadD32 和 PA1221的结构比较表明 PhU-AMS 阻断了酰基链加载到 Pks2 上。这项研究揭示了基于结构的Mtb FadD23 特异性抑制剂和 FAAL 通用抑制剂的设计。