title: Clonostachys rosea demethiolase STR3 controls the conversion of methionine into methanethiol.
abstract: Eukaryote-derived methioninase, catalyzing the one-step degradation of methionine (Met) to methanethiol (MTL), has received much attention for its low immunogenic potential and use as a therapeutic agent against Met-dependent tumors. Although biological and chemical degradation pathways for Met-MTL conversion are proposed, the concrete molecular mechanism for Met-MTL conversion in eukaryotes is still unclear. Previous studies demonstrated that α-keto-methylthiobutyric acid (KMBA), the intermediate for Met-MTL conversion, was located extracellularly and the demethiolase STR3 possessed no activities towards Met, which rule out the possibility of intracellular Met-MTL conversion pathway inside eukaryotes. We report here that degradation of Met resulted in intracellular accumulation of KMBA in Clonostachys rosea. Addition of Met to culture media led to the production of MTL and downregulation of STR3, while incubation of Met with surrogate substrate α-ketoglutaric acid enhanced the synthesis of MTL and triggered the upregulation of STR3. Subsequent biochemical analysis with recombinant STR3 showed that STR3 directly converted both Met and its transamination product KMBA to MTL. These results indicated that STR3 as rate-limiting enzyme degrades Met and KMBA into MTL. Our findings suggest STR3 is a potential target for therapeutic agents against Met-dependent tumors and aging.
authors.affiliation: Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology, Wuhan 430068 China.
authors.forename: Kai-Zhi
authors.initials: KZ
authors.lastname: Jia
authors.affiliation: Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology, Wuhan 430068 China.
authors.forename: Quan
authors.initials: Q
authors.lastname: Zhang
authors.affiliation: Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology, Wuhan 430068 China.
authors.forename: Lin-Yang
authors.initials: LY
authors.lastname: Sun
authors.affiliation: Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology, Wuhan 430068 China.
authors.forename: Yang-Hua
authors.initials: YH
authors.lastname: Xu
authors.affiliation: Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology, Wuhan 430068 China.
authors.forename: Hong-Mei
authors.initials: HM
authors.lastname: Li
authors.affiliation: Key Laboratory of Fermentation Engineering (Ministry of Education), Hubei Provincial Key Laboratory of Industrial Microbiology, Hubei Provincial Cooperative Innovation Center of Industrial Fermentation, Hubei University of Technology, Wuhan 430068 China.
authors.forename: Ya-Jie
authors.initials: YJ
authors.lastname: Tang
mesh_terms: D000595:Amino Acid Sequence; D013437:Carbon-Sulfur Lyases / Q000235:genetics / Q000378:metabolism*; D002853:Chromatography, Liquid; D003470:Culture Media / Q000737:chemistry; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D007656:Ketoglutaric Acids / Q000494:pharmacology; D013058:Mass Spectrometry; D008715:Methionine / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D004718:Saccharomycetales / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D016415:Sequence Alignment; D013379:Substrate Specificity; D013438:Sulfhydryl Compounds / Q000378:metabolism*
chemical_list: D003470:Culture Media; D005656:Fungal Proteins; D007656:Ketoglutaric Acids; D011994:Recombinant Proteins; D013438:Sulfhydryl Compounds; C005231:methylmercaptan; C014632:2-keto-4-methylthiobutyric acid; D008715:Methionine; D013437:Carbon-Sulfur Lyases; C021558:L-methionine gamma-lyase