A new carbon catabolite repression mutation of Escherichia coli, mlc, and its use for producing isobutanol
A new carbon catabolite repression mutation of Escherichia coli, mlc, and its use for producing isobutanol
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DOI：
10.1016/j.jbiosc.2012.02.029
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发表时间：
2012-07-01
影响因子：
2.8
通讯作者：
Tamura, Tomohiro
中科院分区：
文献类型：
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作者：
Nakashima, Nobutaka;Tamura, Tomohiro
从生物质中提取的糖通常是葡萄糖和其他糖的混合物。当混合糖被喂给大肠杆菌时，葡萄糖被优先利用，而其他糖则不被利用。这种现象被称为碳分解代谢抑制（CCR）。为了有效地利用混合糖，我们分离了一个新的大肠杆菌突变体，该突变体对CCR呈阴性。突变菌株在编码碳水化合物代谢全局转录抑制因子的mlc启动子区域有核苷酸替代。所鉴定的突变被命名为mlc*，是一个启动子型，mlc*启动子的活性比野生型mlc启动子高17倍。因此，mlc*突变导致mlc过表达和PtsG缺乏，后者是一种被mlc抑制的葡萄糖特异性渗透酶。已知ptsG （Delta ptsG）的破坏可诱导ccr阴性表型；mlc*菌株也通过相同的机制表现出相同的表型。作为mlc*菌株的一个样本应用，我们从混合糖中生产异丁醇。使用葡萄糖、木糖混合糖，菌株产生的异丁醇比亲本野生型菌株多1.4倍。此外，与其他ccr阴性菌株、Delta ptsG和crp*（编码cAMP受体蛋白构成活性突变体的crp*）相比，mlc*菌株产生了相似或更多的异丁醇。总之，mlc*菌株是一种新的ccr阴性菌株，可用于从混合糖中生产有价值的化合物。(C) 2012，生物技术学会，日本。版权所有。
Sugar derived from biomass is usually a mixture of glucose and other sugars. When mixed sugars are fed to Escherichia coli, glucose is preferentially utilized while other sugars remain unutilized. This phenomenon is known as carbon catabolite repression (CCR). To utilize mixed sugars effectively, we isolated a new E. coli mutant that is negative for CCR. The mutant strain was revealed to have a nucleotide substitution at the promoter region of mlc encoding a global transcriptional repressor for carbohydrate metabolism. The identified mutation, named mlc*, was a promoter-up type, and the mlc* promoter exhibited 17-fold higher activity than the wild-type mlc promoter. Therefore, the mlc* mutation causes Mlc overexpression and a shortage of PtsG, which is a glucose-specific permease that is repressed by Mlc. The disruption of ptsG (Delta ptsG) is known to induce a CCR-negative phenotype; the mlc* strain also exhibits the same phenotype via the same mechanism. As a sample application of the mlc* strain, we produced isobutanol from mixed sugars. Using glucose xylose mixed sugar, the mlc* strain produced 1.4-fold more isobutanol than the parental wild-type strain. Also, the mlc* strain produced similar or greater amounts of isobutanol than other CCR-negative strains, Delta ptsG and crp* (crp*, encoding the constitutive-active mutant of cAMP receptor protein). In conclusion, the mlc* strain is a new CCR-negative strain that is useful for producing valuable compounds from mixed sugars. (C) 2012, The Society for Biotechnology, Japan. All rights reserved.