Structural basis and mechanism of SAM-utilizing PLP-dependent enzymes

s -腺苷甲硫氨酸(SAM)-利用磷酸吡哆醛（PLP）依赖酶（SAM-PLP酶）是一个新兴的生物催化剂家族，其突出的化学多功能性植根于碳稳定辅助因子PLP的组合和增强的反应活性以及含硫SAM的多功能性质。报道的酶介导的转化范围从分子内环丙基化到分子间clisen样反应，形成C-N键的aza- michael型加成，或通过(3+2)-环加成形成串联C-C键。可获得的基因组和宏基因组数据数量的稳步增长为通过目标数据挖掘发现新型生物催化剂提供了巨大的资源。然而，由于目前对SAM-PLP酶缺乏深入的结构和机理知识，没有基于序列数据的功能注释方法。该项目的目标是阐明SAM- plp酶结合和转化SAM的关键结构和机制决定因素，以及随后通过基因组数据挖掘开发用于靶向酶发现方法的生物信息学工具。该研究结果将为深入了解SAM的酶学和进化功能提供帮助，并为探索和开发多功能SAM- plp生物催化剂奠定基础。

S-adenosylmethionine (SAM)-utilizing pyridoxal phosphate (PLP)-dependent enzymes (SAM-PLP enzymes) are an emerging family of biocatalysts that stand out in terms of their remarkable chemical versatility rooted in the combined and potentiated reactivities of the carbanion-stabilizing cofactor PLP and the multifunctional nature of the sulfonium-bearing SAM. Reported enzyme-mediated transformations range from intramolecular cyclopropylations, to intermolecular Claisen-like reactions, C-N bond-forming aza-Michael-type additions, or tandem C-C bond formations via (3+2)-cycloaddition. The steadily increasing number of available genomic and metagenomic data represents a vast resource for the discovery of novel biocatalysts by targeted data mining. However, due to the current lack of in-depth structural and mechanistic knowledge for SAM-PLP enzymes, no methods are available for functional annotation based on sequence data. The goal of the project is to elucidate key structural and mechanistic determinants for SAM binding and conversion by SAM-PLP enzymes and the subsequent development of bioinformatic tools for targeted enzyme discovery approaches by genomic data mining. The results will provide a deeper understanding of the enzymological and evolutionary functions of SAM and will lay the basis to explore and exploit the versatile group of SAM-PLP biocatalysts.