Department of Applied Chemistry and Biotechnology, Chiba University, Chiba, Japan.
Research Institute for Production Development, Kyoto, Japan.
PLoS One. 2019 May 14;14(5):e0216729. doi: 10.1371/journal.pone.0216729. eCollection 2019.
Substrate tolerance of bacterial cyclases has been demonstrated in various contexts, but little is known about that of plant cyclases. Here, we tested two plant ε-cyclases to convert C50-lycopene, which we previously established by rounds of directed evolution. Unlike bacterial β-cyclases, two-end cyclase from lettuce exhibited complete specificity against this molecule, indicating that this enzyme has some mechanism that exerts size-specificity. Arabidopsis one-end cyclase At-y2 showed detectable activity to C50-lycopene. Interestingly, we found that it functions as a two-end cyclase in a C50 context. Based on this observation, a possible model for substrate discrimination of this enzyme is proposed.
已经在各种情况下证明了细菌环化酶对底物的耐受性，但对植物环化酶的了解甚少。在这里，我们测试了两种植物 ε-环化酶来转化 C50-番茄红素，这是我们之前通过定向进化建立的。与细菌β-环化酶不同，生菜的两端环化酶对这种分子表现出完全的特异性，这表明该酶具有某种大小特异性的机制。拟南芥一端环化酶 At-y2 对 C50-番茄红素表现出可检测的活性。有趣的是，我们发现它在 C50 环境中作为两端环化酶发挥作用。基于这一观察结果，提出了该酶底物识别的可能模型。
