Studies On Synthesis Of S-adenosy-L-methionine From DL-methionine In An Metabolically Engineered Saccharomyces Cerevisiae

S-adenosyl-L-methionine(SAM)plays important roles in trans-methylation,trans-sulphuration and polyamine synthesis in all living cells,and it’s also an effective cure for liver disease,depressive syndromes and osteoarthritis.D-methionine can not be directly utilized by organisms,so L-methinonine plays important roles in synthesizing SAM in all living cells.There is a pressing need to transform D-methinonine into L-methinonine to avoid the waste in producing industrial methionine.In this study,genetic and metabolic engineering technology was used to transform D-methinonine into SAM in a model strain BY4741.hpa3 was disrupted by using Mark-rescure gene disruption technology to increase D-methionine accumulation in BY4741.Besides,D-amino acid oxidase and L-Phenylalanine dehydrogenase were overexpressed by introducing the mutiple-copy recombinant plasmid pR426 into BY4741(△hpa3),and the crude enzyme activities of D-amino acid oxidase and L-Phenylalanine dehydrogenase were measured in this study.SAM productivitis in 100mL flask were further measured among genetic engineering strains.In flask medium,experiment data showed that SAM production and SAM content of BY4741(△hpa3 + pR426)increased 18.3%and 31.2%respectively,comparing to its parent strain B Y4741.CRISPR/Cas9 system,as a simple tool for targeted and marker free genome engineering,was used in this study to edit hpa3 and erg6,and provide a method basis of regulating the metabolic pathway of SAM in BY4741.