Mining Of Novel Lanthipeptide In Myxobacteria And Elucidation Of Its Biosynthetic Pathways

In recent decades,the problem of microbial resistance has become increasingly serious,and fewer effective drugs have been sold on the market.Microbial secondary metabolites are important sources of finding bioactive natural products with medicinal potential.Among them,RiPPs have received extensive attention from academic circles and industry due to their remarkable structural and functional diversity.Lanthipeptides are the largest family of RiPPs with characteristic thioether ring structure in the molecule.These compounds have various biological activities including antibacterial,antiviral,antitumor,etc.Genomic data analysis shows that currently known lanthipeptides are only the tip of the iceberg which exists in nature,and there are a large number of unknown natural resources to be discovered and elucidated.As one of the most abundant sources of natural products,myxobacteria can produce a series of secondary metabolites with different structures and biological activities,such as Epothilone D and Ixabepilone,which have been used in clinical cancer treatment.Genome sequencing revealed that the myxobacteria genome encodes rich biosynthetic genes clusters for microbial natural products.However,for many years,there are few reports on lanthipeptides from myxobacteria,which are still underexplored resources.Therefore,in the post-genome era,it is promising to use genome mining strategy to explore the potential lanthipeptides biosynthetic gene clusters in myxobacteria.This study aims to mine the genome of the Hyalangium minutum MCY4189.Bioinformatics analysis identified a novel class Ⅱ lanthipeptide biosynthetic gene cluster hmi.The hmi gene cluster encodes a lanthionine synthase,HmiM,and two precursor peptides,HmiA1 and HmiA2.By using the strategy of co-expression of the precursor peptide and related post-modification enzymes in E.coli,combined with in vitro cleavage experiments of the leader peptide,the structure of the heterologously expressed product of hmi gene cluster was resolved,and the activities of dehydration and cyclization modification were characterized.It was found that both the two precursor peptides could be modified by HmiM.HmiA1 was catalyzed by HmiM to produce a novel thioether ring structure with a large ring nested with a small ring,while HmiA2 was modified by HmiM to form a thioether ring and eleven dehydrated amino acids.In addition,hmi gene cluster also encodes a short-chain reductase HmiSDR.This study preliminarily explored its physiological function through in vivo and in vitro experiments.In conclusion,this study found a novel class Ⅱ two-component lanthipeptide from myxobacteria using a biosynthesis strategy based on genome mining,which has expanded the structural diversity of lanthipeptides.Through the analysis of biosynthetic pathways,the enzyme elements with novel biological functions are optimized,it provides a basis for the artificial design,synthesis and engineering of these compounds.In addition,this study also provides new insights into the biosynthesis of RiPPs and lanthipeptides in myxobacteria.