抑制剂对Pichia生产S-腺苷甲硫氨酸的作用及机制

Influences of Inhibitors on S-adenosyl-L-methionine Production Employing Pichia and the Mechanisms

摘要:

S-腺苷甲硫氨酸(S-adenosyl-L-methionine,SAM)是市场前景广阔的高价值氨基酸。为通过削弱胞内SAM消耗而进一步提高其积累量,作者在诱导型和组成型P.pastoris发酵后期添加3种抑制剂。首先考察其作用并比较其差异,然后分析其机制。结果显示,添加S-腺苷高半胱氨酸水解酶抑制剂Aristeromycin有助于SAM积累,但比较而言,其在诱导型酵母中最适添加质量浓度更低,很可能因为甲醇代谢导致的氧化胁迫使细胞对甲基化作用依赖性增强。添加多胺合成抑制剂DFMA有利于SAM积累,但添加过多对细胞生长和抗氧化不利。组成型酵母中添加7.5 g/L乙酸可通过抑制多胺生成而增强SAM积累。3种抑制剂均可有效提高P.pastoris中SAM产量。

Abstract:

S-adenosyl-L-methionine(SAM) was high-value amino acid that had great market potential.To enhance SAM accumulation by inhibiting its consumption,three inhibitors were added during the late fermentation stage of inducible Pichia and constitutive Pichia.Firstly,their influences were investigated,and the differences were compared,and finally,the mechanisms were analyzed.The results showed that addition of Aristeromycin,an inhibitor of S-adenosyl-L-homocysteine hydrolase,contributed to SAM accumulation,but comparatively speaking,the optimum addition level for inducible Pichia was lower,likely because the oxidative stress resulting from methanol metabolism strengthened the dependence of Pichia cell on transmethylation reaction.Supplement of DFMA,an inhibitor of polyamine synthesis,improved SAM accumulation,while the excessive amount of DFMA led to reduction of cell growth and anti-oxidation ability.Addition of acetic acid at 7.5 g/L improved SAM accumulation,through reducing polyamine formation.The three inhibitors mentioned above were proved effective for improvement of SAM production.