作为一种低毒性的广谱抗生素，磷霉素在临床上得到广泛应用。其原料药由化学合成获得，但由于终产物需要手性拆分获得，造成了一定程度的资源浪费和环境污染。所以利用完善解析的合成途径发展合成生物学的方法获得生物来源的磷霉素将是未来的研究方向。基于最新的遗传数据结果，本申请课题以解析此途径中唯一一步未获清晰机理认识的Fom3所催化的甲基化反应机制为研究内容。综合利用生物化学和生物有机等研究方法，全面表征Fom3的生化性质、揭示影响反应活性的关键因素和自由基的反应机制，从而达到提高酶活性和完善反应机理的研究目标。现阶段研究进展包括Fom3蛋白在链霉菌宿主中成功纯化，关键辅基铁硫簇的厌氧重构和部分催化活性的获得。生物信息学分析表明Fom3属于含有近五万个家族成员的S-腺苷甲硫氨酸自由基超家族蛋白，其催化的sp3碳氢键活化和碳碳键的立体选择性形成在现有化学方法上也很难实现，此催化机制的研究具有重要科学意义。

As one kind of low toxicity and broad spectrum antibiotic, fosfomycin was widely used in clinic. The raw materials of fosfomycin were chemical synthesized, due to the necessary of chiral sepration to acquire the final products, chemical synthsis of fosfomycin caused resource waste and environmental pollution to some extent. Hence take advantage of synthetic biology strategies base on the fully resolved biosynthetic pathway to generate microbe originated fosfomycin would be a prospective research direction. Upon the latest genetic research data, this project would focused on the study of the only unresolved methylation mechanism catalyzed by Fom3 involved in fosfomycin biosynthesis pathway. By the method of biochemical and bioorganic chemistry, our goal is to fully characterize the biochemical properties of Fom3, reveal the key influencing factor of the reactivity and the mechanism of radical reactions. Current research progress includes: successfully purified Fom3 protein from Streptomyces expression host, recomposed the key [Fe4-S4] cluster under anaerobic condition and subsequently acquired partial catalytic activity of Fom3. Bioinformatics analysis shows Fom3 belongs to Radical SAM super family proteins which contain about fifty thousand members, by which catalyzed the C-H activation and C-C stereo selectively formation also hardly to achieve by chemical strategies, this kind of catalytic mechanistic study has important scientific significance.