以磷连氮霉素Fosfazinomycin为模型的天然产物联氨基团的生物合成机制研究

含有氮氮键的天然产物，如腙、酰肼、氧化偶氮、重氮和含氮杂环化合物等，大都表现出良好的生物活性。磷连氮霉素是链霉菌产生的寡肽类小分子化合物，能够有效抑制真菌，含有奇特的“碳-氮-氮-磷-碳”（C-N-N-P-C）杂原子骨架单元。N-N单键连接的部分是联氨基团，分子从氨基端往羧基端形成精氨酰肼，从羧基端往氨基端形成膦酰肼。现有的研究已经证实磷连氮霉素的精氨酰肼部分和膦酸部分（含有P-C键）先分别合成，然后再通过N-P键连接起来，但是磷连氮霉素联氨基团的合成途径却从未被揭示。本研究将通过基因敲除、化合物喂养和中间体鉴定，确定与联氨基团合成直接相关的基因。然后，我们将通过体外生化反应重构联氨基团的形成过程，借助有机化学手段捕捉和确证酶学反应中间体，从而揭示一例全新的天然产物联氨基团生物合成机制。这既能完善我们对磷连氮霉素生物合成的理解，也能丰富我们对涉氮生物化学反应的认识。

The nitrogen-nitrogen bond-containing natural products, including hydrazone, hydrazide, azoxy, diazo and heterocyclic compound, show fascinating biological activities. Fosfazinomycin, an oligopeptide natural product produced by Streptomyces, exhibits notable anti-fungi activity. It harbors a unique C-N-N-P-C heteroatom moiety, which forms an argininyl hydrazide from the amino-terminal to carboxyl terminal, and a phosphonic hydrazide in the reverse direction. All of the documented research results demonstrated that the biosynthesis of fosfazinomycin is a convergent process, in which the argininyl hydrazide part and the phosphonate part (harbors P-C bond) was synthesized independently and then conjugated by a N-P bond. However, enzymatic formation of the N-N bond remains obscure until now. In this study, gene knock-out, feeding experiments and biosynthetic intermediates identification will be employed to narrow down the genes directly related to the formation of N-N bond in fosfazinomycin biosynthesis. To reveal the biosynthetic pathway of hydrazine functional group, we will reconstitute the N-N bond in vitro by biochemical reactions and characterize the enzymatic intermediates by organic chemical approaches. It will deepen our understanding about the fosfazinomycin biosynthesis and expand our knowledge about nitrogen-involved biochemical reactions.