Department of Biotechnology, Konkuk University, Chungju 27478, Chungbuk, Republic of Korea.
Research Institute for Biomedical & Health Science, Konkuk University, Chungju 27478, Chungbuk, Republic of Korea.
Int J Mol Sci. 2023 Feb 4;24(4):3121. doi: 10.3390/ijms24043121.
Flavin adenine dinucleotide synthetases (FADSs) catalyze FAD biosynthesis through two consecutive catalytic reactions, riboflavin (RF) phosphorylation and flavin mononucleotide (FMN) adenylylation. Bacterial FADSs have RF kinase (RFK) and FMN adenylyltransferase (FMNAT) domains, whereas the two domains are separated into two independent enzymes in human FADSs. Bacterial FADSs have attracted considerable attention as drug targets due to the fact that they differ from human FADSs in structure and domain combinations. In this study, we analyzed the putative FADS structure from the human pathogen (FADS) determined by Kim et al., including conformational changes of key loops in the RFK domain upon substrate binding. Structural analysis and comparisons with a homologous FADS structure revealed that FADS corresponds to a hybrid between open and closed conformations of the key loops. Surface analysis of FADS further revealed its unique biophysical properties for substrate attraction. In addition, our molecular docking simulations predicted possible substrate-binding modes at the active sites of the RFK and FMNAT domains. Our results provide a structural basis to understand the catalytic mechanism of FADS and develop novel FADS inhibitors.
黄素腺嘌呤二核苷酸合酶（FADSs）通过两个连续的催化反应催化 FAD 生物合成，即核黄素（RF）磷酸化和黄素单核苷酸（FMN）腺苷酰化。细菌 FADSs 具有 RF 激酶（RFK）和 FMN 腺苷酰转移酶（FMNAT）结构域，而人类 FADSs 中的这两个结构域则分为两个独立的酶。由于细菌 FADSs 在结构和结构域组合上与人类 FADSs 不同，因此它们作为药物靶点引起了相当大的关注。在这项研究中，我们分析了 Kim 等人确定的人类病原体（FADS）的假定 FADS 结构，包括底物结合时 RFK 结构域中关键环构象的变化。结构分析和与同源 FADS 结构的比较表明，FADS 对应于关键环的开环和闭环构象之间的杂种。FADS 的表面分析进一步揭示了其独特的物理化学性质，有利于吸引底物。此外，我们的分子对接模拟预测了 RFK 和 FMNAT 结构域活性位点的可能底物结合模式。我们的研究结果为理解 FADS 的催化机制和开发新型 FADS 抑制剂提供了结构基础。
