Iron-dependent lipoxygenases (LOXs) are involved in the synthesis of oxylipins from polyunsaturated fatty acids. However, they are usually difficult to overexpress in functional form in microbial cell factories. Moreover, 9-LOXs, generating 9-hydroperoxy fatty acids from C18 polyunsaturated fatty acids, have rarely been found from microbial sources. Here, we discovered a novel 9S-LOX in the marine myxobacterium Enhygromyxa salina (Es-9S-LOX). The recombinant enzyme produced in Escherichia coli exhibited remarkable activity in the dioxygenation of linoleic acid (LA, 1), α-linolenic acid, γ-linolenic acid, and arachidonic acid specifically at the C9 position to yield the product with (S)-configuration at catalytic efficiency of 3.94, 1.42, 1.38, and 0.69 μM^–1·s^–1, respectively. The elucidated X-ray crystal structure of Es-9S-LOX reveals a long and narrow hydrophobic pocket that allows the substrate to be near the metal ion and the oxygen tunnel. The enzyme was successfully used in a chemoenzymatic reaction to generate a hydroxy fatty acid from LA. Our study thus contributes to the valorization of renewable polyunsaturated fatty acids into a variety of fatty acid derivatives, including hydroxy fatty acids.

中文翻译：

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来自盐藻 Enhygromyxa 的新型 9S-脂氧合酶的发现和分子表征，用于脂肪酸生物转化


铁依赖性脂氧合酶 （LOX） 参与从多不饱和脂肪酸合成脂氧化物。然而，它们通常很难在微生物细胞工厂中以功能形式过表达。此外，从 C18 多不饱和脂肪酸生成 9-氢过氧脂肪酸的 9-LOX 很少从微生物来源中发现。在这里，我们在海洋粘液菌 Enhygromyxa salina （Es-9S-LOX） 中发现了一种新的 9S-LOX。大肠杆菌中产生的重组酶在亚油酸 （LA， 1）、α-亚麻酸、γ-亚麻酸和花生四烯酸的双氧合反应中表现出显著的活性，特别是在 C9 位点产生具有 （S） 构型的产物，催化效率分别为 3.94、1.42、1.38 和 0.69 μM^–1·s–1。阐明的 Es-9 S-LOX 的 X 射线晶体结构揭示了一个狭长的疏水袋，使衬底能够靠近金属离子和氧隧道。该酶成功用于化学酶反应，从 LA 生成羟基脂肪酸。因此，我们的研究有助于将可再生多不饱和脂肪酸价值化为各种脂肪酸衍生物，包括羟基脂肪酸。