NEW APPROACH TO TRYPTOPHAN PRODUCTION BY ESCHERICHIA-COLI - GENETIC MANIPULATION OF COMPOSITE PLASMIDS INVITRO
NEW APPROACH TO TRYPTOPHAN PRODUCTION BY ESCHERICHIA-COLI - GENETIC MANIPULATION OF COMPOSITE PLASMIDS INVITRO
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DOI：
10.1128/aem.43.2.289-297.1982
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发表时间：
1982-01-01
影响因子：
4.4
通讯作者：
IMANAKA, T
中科院分区：
文献类型：
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作者：
AIBA, S;TSUNEKAWA, H;IMANAKA, T
为了研究大肠杆菌合成L色氨酸的能力，将色氨酸合成酶和邻氨基苯甲酸磷酸核糖转移酶(邻氨基苯甲酸聚合体)的色氨酸操纵子(trp操纵子)的缺失突变体分别转化到对色氨酸抑制不敏感的突变体中。除了从pSC101trp.cntdo.I15等质粒所需的反馈抑制中释放邻氨基苯甲酸酯聚集体外，色氨酸抑制(Trpr)和色氨酸酶缺乏症(TNAA)这两种特性对宿主菌株都是必不可少的，如TNA(TrpAE1 Trpr Tna A)。评估了基因剂量对色氨酸合成酶活性和色氨酸产量的影响。适中的质粒拷贝数.apprx。5/染色体，色氨酸产量最高。适当地从反馈抑制中释放邻氨基苯甲酸酯聚集体也是防止代谢异常的必要步骤。如果进一步诱变pSC101trp.cntdot.I15(pSC101trp.cntdot.I15.cntdot.14)，并将其转入TNA细胞，则可有效地提高色氨酸的产量。虽然在用这种方法实现色氨酸的商业化生产之前，还需要进一步改进宿主-质粒系统，但朝着这个目标迈出了有希望的一步。
To study the production of L-tryptophan by E. coli, the deletion mutants of the trp operon (trpAE1) were transformed with mutant plasmids carrying the trp operon whose anthranilate synthase and phosphoribosyl anthranilate transferase (anthranilate aggregate), respectively, had been desensitized to tryptophan inhibition. In addition to release of the anthranilate aggregate from the feedback inhibition required for plasmids such as pSC101 trp.cntdot.I15, the properties of trp repression (trpR) and tryptophanase deficiency (tnaA) were both indispensable for host strains such as strain Tna (trpAE1 trpR tnaA). The gene dosage effects on tryptophan synthase activities and on production of tryptophan were assessed. A moderate plasmid copy number, .apprx. 5/chromosome, was optimal for tryptophan production. An appropriate release of the anthranilate aggregate from feedback inhibition was also a necessary step to ward off the metabolic anomaly. If the mutant plasmid pSC101 trp.cntdot.I15 was further mutagenized (pSC101 trp.cntdot.I15.cntdot.14) and then transferred to Tna cells, an effective enhancement of tryptophan production was achieved. Although further improvement of the host-plasmid system is needed before commercial production of tryptophan can be realized by this means, a promising step toward this goal has been established.