Biosynthesis of Sodorifen, Chlororaphen and Related Compounds

点击翻译按钮获取中文摘要

Sodorifen and chlororaphen are non-canonical methylated terpenes of bacterial origin. Their biosynthesis will be studied by cloning and heterologous expression of the genes encoded in biosynthetic gene clusters in Serratia plymuthica and Pseudomonas chlororaphis, respectively. Two related biosynthetic gene clusters containing homologous genes to those observed in the biosynthetic gene clusters of sodorifen and chlororaphen are found in Variovorax boronicumulans and Pseudomonas grimontii, but the products of these gene clusters are unknown. Also for these clusters enzyme expression constructs will be made available to enzymatically generate the unknown products for isolation and structure elucidation. Incubation experiments with isotopically labelled precursors will be performed to elucidate the complex cyclisation mechanisms and to determine the absolute configurations of the methylated terpenoids. This work will be supported by DFT calculations. The structures of the methyltransferases and the non-canonical terpene synthases involved in sodorifen and chlororaphen biosynthesis are unknown. These enzymes will be crystallised together with non-reactive analogs of their native substrates that will be synthesised. Based on the obtained crystal structures site-directed mutagenesis experiments will be performed to gain deeper insights into the enzyme mechanisms. Substrate analogs with additional methylations will be synthesised and enzymatically converted with the terpene synthases for sodorifen and chlororaphen biosynthesis. The obtained products will be purified and their structures will be elucidated. Taken together, this project aims at a deep mechanistic understanding of the unusual enzymes involved in the biosynthesis of sodorifen, chlororaphen and related molecules.