重组Rhodobacter sphaeroides hemA表达的调控  

Regulation on Expression of Recombinant Rhodobacter sphaeroides hemA

作　　者：王俊卿[1] 张肇铭[1] 

机构地区：[1]山西大学生命科学与技术学院,太原030006

出　　处：《中国生物化学与分子生物学报》2005年第4期488-492,共5页Chinese Journal of Biochemistry and Molecular Biology

基　　金：国家科技部攻关项目(No.2001BA540C)~~

摘　　要：RhodobactersphaeroideshemA编码5氨基乙酰丙酸合酶(ALAS),催化磷酸吡哆醛依赖性琥珀酰CoA和甘氨酸缩合成ALA.将R.spaeroideshemA导入E.coli进行表达,当hemA具有与lac启动子相同的转录方向时,ALAS有活性.lac启动子与hemA之间的距离会影响ALAS在不同培养基上的表达.E.coli宿主菌对ALAS表达、ALA产量有显著影响,在实验所用6种菌株中,E.coliDH1是最佳宿主菌(P<0.05).ALAS表达还与碳源有关,琥珀酸为碳源时,重组ALAS活性最高(P<0.05),以乳酸为碳源时,ALAS活性很低.重组ALAS活性也受培养基pH值影响,pH6.5时,活性最高(P<0.05).Rhodobacter sphaeroides hemA gene encoding for 5-aminolevulinic acid synthase （ALAS）, which catalyzes pyridoxal phosphate-dependent condensation of succinyl coenzyme A and glycine forming ALA. R. sphaeroides hemA gene in pALA vector system was transformed into E. coli. ALA synthase activity level was maximal when hemA had the same transcription direction as the lac promoter. The distance between the lac promoter and hemA affected the expression of ALA synthase on different growth substrates. And E. coli host strain had an significant effect on recombinant ALA synthase activity level and ALA production, with E. coli DH1 being best suited among six host strains studied （P〈0.05）. ALA synthase activity was also dependent on the carbon sources. Succinate gave the highest level of ALA synthase activity （P〈0.05 ）, while lactose resulted in a repression of ALA synthase. ALA synthase activity level was also dependent on medium pH, with maximal activity occurring at pH 6.5 （P〈0.05）.

关 键 词：5-氨基乙酰丙酸合酶 同工酶hemA 基因表达调控 宿主菌 培养基 

分 类 号：Q786[生物学—分子生物学] Q756