多胺对毕赤酵母合成S-腺苷甲硫氨酸的影响

Influence and Mechanism of Polyamines Addition on S-adenosyl-L-methionine Synthesis by Pichia pastoris

摘要:

S-腺苷甲硫氨酸（S-adenosyl-L-methionine，SAM）是一种需求量巨大的活性氨基酸。SAM生产主要是利用过表达甲硫氨酸腺苷转移酶（methionine adenosyltransferase，MAT）的毕赤酵母（Pichia pastoris）进行胞内合成，但较高密度培养条件下甲醇诱导会造成一定程度的细胞死亡。本研究首先揭示甲醇对P. pastoris造成过氧化损伤，然后分析了添加多胺（腐胺和亚精胺）对SAM合成影响及机制。结果揭示多胺可提高H2O2酶活力，从而缓解细胞氧化损伤，此外还改善了MAT酶活力和细胞生长，最终SAM的积累水平提高19.2%。

Abstract:

S-adenosyl-L-methionine (SAM) was a type of active amino acid required largely. SAM was mainly produced through the biosynthesis reaction within Pichia pastoris cell that overexpressed methionine adenosyltransferase (MAT), while the inducer methanol led to cell death at some extent during cultivation process with high cell density. Thus this study firstly revealed that methanol exerted oxidative stress on P. pastoris cell, and then investigated the influences of adding polyamines (putrescine and spermidine) on SAM biosynthesis and reaction mechanism. The results revealed that polyamines can lessen oxidative damage through elevating catalase activity, and additionally, improving MAT activity and cell growth. As a result, 19.2% higher level of SAM deposit was achieved.