Recently, human genetic studies identified an association of single-nucleotide polymorphisms (SNPs) in the HSD17B13 (17-beta hydroxysteroid dehydrogenase 13) gene with alcoholic and nonalcoholic fatty liver disease (NAFLD) development. Mutant HSD17B13 variants devoid of enzymatic function have been demonstrated to be protective from cirrhosis and liver cancer, supporting the development of HSD17B13 as a promising therapeutic target. Previous studies have demonstrated HSD17B13 is a lipid droplet (LD) associated protein. However, the critical domains that drive LD targeting or determine the enzymatic activity are yet to be defined. Here we used mutagenesis to generate multiple truncated and point-mutated proteins and were able to demonstrate in vitro that the N-terminal hydrophobic domain, PAT-like domain, and a putative α-helix/β-sheet/α-helix domain in HSD17B13 are all critical for LD targeting. Similarly, we characterized the predicted catalytic, substrate-binding, and homodimer interaction sites and found them essential for the enzymatic activity of HSD17B13, in addition to our previous identification of amino acid P260 and cofactor binding site. In conclusion, we identified critical domains and amino acid sites that are essential for the LD localization and protein function of HSD17B13, which may facilitate understanding of its function and targeting of this protein to treat chronic liver diseases.

中文翻译：

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HSD17B13 中用于细胞定位和酶活性的基本结构域的表征。

最近，人类遗传研究确定了 HSD17B13（17-β 羟基类固醇脱氢酶 13）基因中的单核苷酸多态性 (SNP) 与酒精性和非酒精性脂肪肝 (NAFLD) 发展之间的关联。缺乏酶功能的突变 HSD17B13 变体已被证明可预防肝硬化和肝癌，支持将 HSD17B13 开发为有希望的治疗靶点。先前的研究表明 HSD17B13 是一种脂滴 (LD) 相关蛋白。然而，驱动 LD 靶向或确定酶活性的关键域尚未确定。在这里，我们使用诱变来产生多个截短和点突变的蛋白质，并且能够在体外证明 N 端疏水结构域、PAT 样结构域、HSD17B13 中假定的 α-螺旋/β-折叠/α-螺旋结构域对于 LD 靶向都是至关重要的。类似地，我们对预测的催化、底物结合和同二聚体相互作用位点进行了表征，发现它们对 HSD17B13 的酶活性至关重要，除了我们之前对氨基酸 P260 和辅因子结合位点的鉴定。总之，我们确定了对 HSD17B13 的 LD 定位和蛋白质功能必不可少的关键结构域和氨基酸位点，这可能有助于了解其功能和该蛋白质治疗慢性肝病的靶向作用。除了我们之前对氨基酸 P260 和辅因子结合位点的鉴定之外。总之，我们确定了对 HSD17B13 的 LD 定位和蛋白质功能必不可少的关键结构域和氨基酸位点，这可能有助于了解其功能和该蛋白质治疗慢性肝病的靶向作用。除了我们之前对氨基酸 P260 和辅因子结合位点的鉴定之外。总之，我们确定了对 HSD17B13 的 LD 定位和蛋白质功能必不可少的关键结构域和氨基酸位点，这可能有助于了解其功能和该蛋白质治疗慢性肝病的靶向作用。