Department of Chemical & Biological Engineering, Korea University, Seoul 136-763, Korea.
Samyang Corp. 295 Pangyo-ro, Bundang-gu, Seongnam-si, Gyeonggi-do 13488, Republic of Korea.
J Ind Microbiol Biotechnol. 2023 Feb 17;50(1). doi: 10.1093/jimb/kuad026.
S-methyl-methionine (SMM), also known as vitamin U, is an important food supplement produced by various plants. In this study, we attempted to produce it in an engineered microorganism, Saccharomyces cerevisiae, by introducing an MMT gene encoding a methionine S-methyltransferase from Arabidopsis thaliana. The S. cerevisiae sake K6 strain, which is a Generally Recognized as Safe (GRAS) strain, was chosen as the host because it produces a significant amount of S-adenosylmethionine (SAM), a precursor of SMM. To increase SMM production in the host, MHT1 and SAM4 genes encoding homocysteine S-methyltransferase were knocked out to prevent SMM degradation. Additionally, MMP1, which encodes S-methyl-methionine permease, was deleted to prevent SMM from being imported into the cell. Finally, ACS2 gene encoding acetyl-CoA synthase was overexpressed, and MLS1 gene encoding malate synthase was deleted to increase SAM availability. Using the engineered strain, 1.92 g/L of SMM was produced by fed-batch fermentation.
ONE-SENTENCE SUMMARY: Introducing a plant-derived MMT gene encoding methionine S-methyltransferase into engineered Saccharomyces cerevisiae sake K6 allowed microbial production of S-methyl-methionine (SMM).
S-甲基甲硫氨酸（SMM），也称为维生素 U，是一种由各种植物产生的重要食品补充剂。在本研究中，我们试图通过引入来自拟南芥的蛋氨酸 S-甲基转移酶的 MMT 基因，在工程微生物酿酒酵母中生产它。酿酒酵母清酒 K6 菌株是一种被普遍认为安全（GRAS）的菌株，被选为宿主，因为它产生大量 S-腺苷甲硫氨酸（SAM），这是 SMM 的前体。为了增加宿主中 SMM 的产量，敲除编码同型半胱氨酸 S-甲基转移酶的 MHT1 和 SAM4 基因，以防止 SMM 降解。此外，删除编码 S-甲基甲硫氨酸通透酶的 MMP1，以防止 SMM 被导入细胞。最后，过表达编码乙酰辅酶 A 合酶的 ACS2 基因，并删除编码苹果酸合酶的 MLS1 基因，以增加 SAM 的可用性。使用工程菌株，通过分批补料发酵生产了 1.92g/L 的 SMM。
将源自植物的 MMT 基因，该基因编码蛋氨酸 S-甲基转移酶，导入工程酿酒酵母清酒 K6 中，使得微生物能够生产 S-甲基甲硫氨酸（SMM）。
