肠道菌群脂肪酸代谢通路在抗肿瘤疗效好的组富集，提示增强该通路活性或可提高疗效。革兰氏阴性菌中，GntR家族转录因子FadR是脂肪酸代谢的重要调控因子。与同源蛋白相比，弧菌科FadR具有C-末端40个氨基酸插入序列，该序列或助其成为更高效的转录因子。无配体结合时，该插入序列可稳定DNA结合域wHTH基序的翼状部分，或可增强FadR与DNA的亲和力。此外，该插入序列参与形成全新的可结合额外一分子长链脂酰辅酶A配体的位点，该位点与配体的亲和力低于VcFadR中与大肠杆菌FadR（EcFadR）相似的位点。与只结合一分子配体的EcFadR相比，VcFadR结合两分子配体后，其DNA结合域发生更显著的构象变化，或使其对DNA的亲和力进一步降低。本研究旨在阐明FadR的40个氨基酸插入序列对蛋白构象和功能的影响，同时探索基因工程改造FadR来提高其转录效率的可行性，为未来利用改造菌来提高疗效提供基础。

Fatty acid metabolism pathway is enriched in patients with cancer who respond well to therapy, which suggests the possibility to improve therapeutic efficacy by enhancing the activity of this pathway. In Gram-negative bacteria, the transcription factor FadR of the GntR family is the master regulator of fatty acid metabolism. Among FadR homologues of the GntR family, FadR from Vibrionaceae is unusual in that it contains a C-terminal 40-residue insertion, which may allow VcFadR to function as a more efficient regulator. The 40-residue insertion potentially stabilizes the wing of the wHTH DNA binding domain in the absence of DNA, and may enhance the affinity of VcFadR for DNA in the absence of ligands. Moreover, the 40-residue insertion facilitates the formation of the binding site (site #2) for an additional long chain fatty acyl-CoAs (LCFA-CoAs) ligand, which has not previously been observed. This site #2 is predicted to the lower affinity site for LCFA-CoAs than site #1 in VcFadR, which resembles that of E. coli FadR (EcFadR). Upon binding of two ligands, VcFadR undergoes a dramatic conformational change that would more fully disrupt DNA binding than EcFadR. This project aims to elucidate the conformational and functional changes mediated by the C-terminal 40-residue insertion, and explore the feasibility of genetic engineering of FadR to enhance transcriptional efficiency, which will provide basis for future application of genetic engineered bacteria to improve therapeutic efficacy.