Wirth Samuel E, Pakhomova Svetlana, Belyaeva Olga V, Boeglin William E, Brash Alan R, Newcomer Marcia E, Kedishvili Natalia Y, Popov Kirill M
Department of Biochemistry and Molecular Genetics, University of Alabama at Birmingham, Birmingham, Alabama, USA.
Department of Biological Sciences, Louisiana State University, Baton Rouge, Louisiana, USA.
J Biol Chem. 2025 Sep 11;301(10):110704. doi: 10.1016/j.jbc.2025.110704.
Recent evidence suggests that dehydrogenase reductase 9 (DHRS9) can oxidize and alter the biological activity of a diverse group of oxylipin substrates, underscoring the importance of DHRS9 in regulating various biological processes, including inflammation, cell proliferation, and tissue repair. Importantly, mutations in the DHRS9 gene resulting in amino acid substitutions S202L and D286H have been linked to an early-onset case of epilepsy; whether these mutations affect the function of DHRS9 has not been investigated. The results of this study demonstrate that both mutations cause a significant loss of DHRS9 functionality. However, in the case of the S202L variant, the loss of catalytic activity likely stems from the impaired protein folding and/or protein stability. On the other hand, the D286H DHRS9 mutant protein is relatively more stable than the S202L variant, but its K value for NAD (2.85 mM) is nearly 12-fold higher than that of the wild-type enzyme. The three-dimensional structure of DHRS9, solved in this study, provides insights into the functions of the S202 and D286 residues. In addition, it reveals a strikingly large substrate binding cavity, consistent with the fact that the enzyme can process oxygenated hydrocarbons with abundant rotational freedom and differing lengths (18-22 C). Considering that expression levels of DHRS9 in human tissues are highly sensitive to inflammatory conditions and the existence of naturally occurring mutations in DHRS9, the structural and functional characterization of DHRS9 reported in this study is critical for a better understanding of the role of DHRS9 in inflammatory processes.
最近的证据表明，脱氢酶还原酶9（DHRS9）可以氧化并改变多种氧化脂质底物的生物活性，这突出了DHRS9在调节包括炎症、细胞增殖和组织修复在内的各种生物过程中的重要性。重要的是，DHRS9基因中导致氨基酸替换S202L和D286H的突变与一例早发性癫痫有关；这些突变是否影响DHRS9的功能尚未得到研究。本研究结果表明，这两种突变均导致DHRS9功能显著丧失。然而，对于S202L变体，催化活性的丧失可能源于蛋白质折叠受损和/或蛋白质稳定性下降。另一方面，D286H DHRS9突变蛋白比S202L变体相对更稳定，但其对NAD的K值（2.85 mM）比野生型酶高出近12倍。本研究解析的DHRS9三维结构为S202和D286残基的功能提供了见解。此外，它还揭示了一个惊人的大底物结合腔，这与该酶能够处理具有丰富旋转自由度和不同长度（18 - 22个碳）的氧化烃这一事实相一致。鉴于DHRS9在人体组织中的表达水平对炎症条件高度敏感以及DHRS9中存在自然发生的突变，本研究报道的DHRS9的结构和功能特征对于更好地理解DHRS9在炎症过程中的作用至关重要。
