Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Sendai, Japan.
RIKEN SPring-8 Center, Sayo-gun, Japan.
FEBS Lett. 2024 Jun;598(11):1422-1437. doi: 10.1002/1873-3468.14886. Epub 2024 Apr 22.
Among the epimerases specific to alginate, some of them in Azotobacter genera convert β-d-mannuronic acid to α-l-guluronic acid but also have lyase activity to degrade alginate. The remarkable characteristics of these epimerases make it a promising enzyme for tailoring alginates to meet specific demands. Here, we determined the structure of the bifunctional mannuronan C-5 epimerase AlgE3 from Azotobacter chroococcum (AcAlgE3) in complex with several mannuronic acid oligomers as well as in apo form, which allowed us to elucidate the binding manner of each mannuronic acid oligomer, and the structural plasticity, which is dependent on calcium ions. Moreover, a comprehensive analysis of the lyase activity profiles of AcAlgE3 combined with structural characteristics explained the preference for different chain length oligomers.
在特定的褐藻胶差向异构酶中，有些属于固氮菌属，能够将β-d-甘露糖醛酸转化为α-l-古洛糖醛酸，但也具有裂解酶活性，可降解褐藻胶。这些差向异构酶的显著特点使其成为一种有前途的酶，可以对褐藻胶进行修饰，以满足特定需求。在这里，我们测定了复合几种甘露糖醛酸低聚物以及无配体形式的棕色固氮菌AlgE3 的结构，这使我们能够阐明每个甘露糖醛酸低聚物的结合方式，以及依赖于钙离子的结构可塑性。此外，对 AcAlgE3 的裂解酶活性谱的综合分析结合结构特征，解释了其对不同链长低聚物的偏好。
