Shimizu Nobuhiro, Sakata Daisuke, Schmelz Eric A, Mori Naoki, Kuwahara Yasumasa
Faculty of Bioenvironmental Science, Kyoto Gakuen University, Kameoka 621-8555, Japan;
Faculty of Bioenvironmental Science, Kyoto Gakuen University, Kameoka 621-8555, Japan.
Proc Natl Acad Sci U S A. 2017 Mar 7;114(10):2616-2621. doi: 10.1073/pnas.1612611114. Epub 2017 Feb 21.
Astigmatid mites depend on bioactive glandular secretions, pheromones, and defensive agents to mediate intra- and interspecies interactions. Aliphatic formates, such as (,)-8,11-heptadecadienyl formate (8,11-F17) and ()-8-heptadecenyl formate (8-F17), are rarely encountered natural products that are abundant in sp. Sasagawa (Acari: Acaridae) mite secretions. Linoleic acid and oleic acid are predicted as key intermediates in the synthesis of the closely related aliphatic formates. To gain insight in this biosynthetic pathway, acarid mite feeding experiments were conducted using C-labeled precursors to precisely track incorporation. Analyses using C NMR spectroscopy demonstrated that the C-labeling pattern of the precursors was detectable on formates in exocrine secretions and likewise on fatty acids in total lipid pools. Curiously, the results demonstrated that the formates were biosynthesized without the dehomologation of corresponding fatty acids. Careful examination of the mass spectra from labeling experiments revealed that the carbonyl carbon of the formates is originally derived from the C-1 position of the fatty acids. Consistent with a Baeyer-Villiger oxidation reaction, labeling studies support the insertion of an oxygen atom between the carbonyl group and carbon chain. Empirical data support the existence of a Baeyer-Villiger monooxygenase responsible for the catalyzation of the Baeyer-Villiger oxidation. The predicted existence of a Baeyer-Villiger monooxygenase capable of converting aliphatic aldehydes to formates represents an exciting opportunity to expand the enzymatic toolbox available for controlled biochemical synthesis.
粉螨依靠生物活性腺体分泌物、信息素和防御因子来介导种内和种间相互作用。脂肪族甲酸酯，如（±）-8,11-十七碳二烯基甲酸酯（8,11-F17）和（-）-8-十七碳烯基甲酸酯（8-F17），是在佐川螨（蜱螨亚纲：粉螨科）螨分泌物中大量存在的罕见天然产物。亚油酸和油酸被预测为密切相关的脂肪族甲酸酯合成中的关键中间体。为了深入了解这条生物合成途径，使用碳标记前体进行了粉螨饲养实验，以精确追踪掺入情况。利用碳核磁共振光谱进行的分析表明，前体的碳标记模式在外分泌分泌物中的甲酸酯上以及总脂质池中的脂肪酸上都可检测到。奇怪的是，结果表明甲酸酯的生物合成过程中相应脂肪酸没有发生碳链延长。对标记实验的质谱仔细检查发现，甲酸酯的羰基碳最初源自脂肪酸的C-1位。与拜耳-维利格氧化反应一致，标记研究支持在羰基和碳链之间插入一个氧原子。实验数据支持存在一种负责催化拜耳-维利格氧化的拜耳-维利格单加氧酶。预测存在一种能够将脂肪族醛转化为甲酸酯的拜耳-维利格单加氧酶，这为扩展可用于可控生化合成的酶工具箱提供了一个令人兴奋的机会。
