毕赤酵母含硫氨基酸生物合成途径

Sulfur Amino Acids Biosynthetic Pathway in Pichia pastoris

含硫氨基酸是所有生物生长繁殖不可缺少的氨基酸。尽管毕赤酵母在工业发酵中作为重要的表达菌株,但是其含硫氨基酸的生物合成途径尚未明了。作者采用生物信息学及表型分析的方法,阐明了毕赤酵母含硫氨基酸的生物合成途径。结果表明,毕赤酵母可通过O-乙酰同丝氨酸及O-乙酰丝氨酸与无机硫元素合成含硫氨基酸,甲硫氨酸与半胱氨酸也可通过转硫途径实现相互转化。另外毕赤酵母cys3Δ突变菌株在未添加半胱氨酸的合成培养基中对硒代甲硫氨酸表现出显著的抗性。综上所述,未来有望应用毕赤酵母表达硒蛋白用于蛋白质三级结构的分析。

Sulfur amino acids are essential for all living organisms.Pichia pastoris is a very important expression host in industrial fermentation,while its sulfur amino acids biosynthetic pathway is still unclear.To establish the pathway,bioinformatics approach and phenotypic analysis of mutants were employed in this study.Results indicated that Pichia pastoris synthesizes sulfur amino acids from inorganic sulfate via O-Acetyl-L-Homoserine and O-Acetyl-L-serine pathways.And methionine and cysteine can be inter-conversion by trans-sulfuration pathway.In addition,cys3Δmutant showed selenomethionine resistance without supplementation of cysteine.Taken together,these results suggest a potential use of the cys3Δstrain for the production of selenomethionyl proteins.