Dataset Information

Optimization of the heme biosynthesis pathway for the production of 5-aminolevulinic acid in Escherichia coli.

ABSTRACT: 5-Aminolevulinic acid (ALA), the committed intermediate of the heme biosynthesis pathway, shows significant promise for cancer treatment. Here, we identified that in addition to hemA and hemL, hemB, hemD, hemF, hemG and hemH are also the major regulatory targets of the heme biosynthesis pathway. Interestingly, up-regulation of hemD and hemF benefited ALA accumulation whereas overexpression of hemB, hemG and hemH diminished ALA accumulation. Accordingly, by combinatorial overexpression of the hemA, hemL, hemD and hemF with different copy-number plasmids, the titer of ALA was improved to 3.25 g l(-1). Furthermore, in combination with transcriptional and enzymatic analysis, we demonstrated that ALA dehydratase (HemB) encoded by hemB is feedback inhibited by the downstream intermediate protoporphyrinogen IX. This work has great potential to be scaled-up for microbial production of ALA and provides new important insights into the regulatory mechanism of the heme biosynthesis pathway.

SUBMITTER: Zhang J

PROVIDER: S-EPMC4341193 | biostudies-literature | 2015 Feb

REPOSITORIES: biostudies-literature

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Optimization of the heme biosynthesis pathway for the production of 5-aminolevulinic acid in Escherichia coli.

Zhang Junli J Kang Zhen Z Chen Jian J Du Guocheng G

Scientific reports 20150226

5-Aminolevulinic acid (ALA), the committed intermediate of the heme biosynthesis pathway, shows significant promise for cancer treatment. Here, we identified that in addition to hemA and hemL, hemB, hemD, hemF, hemG and hemH are also the major regulatory targets of the heme biosynthesis pathway. Interestingly, up-regulation of hemD and hemF benefited ALA accumulation whereas overexpression of hemB, hemG and hemH diminished ALA accumulation. Accordingly, by combinatorial overexpression of the hem ...[more]

PMID: 25716896

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Project description:BACKGROUND: With the increasing stress from oil price and environmental pollution, aroused attention has been paid to the microbial production of chemicals from renewable sources. The C12/14 and C16/18 alcohols are important feedstocks for the production of surfactants and detergents, which are widely used in the most respected consumer detergents, cleaning products and personal care products worldwide. Though bioproduction of fatty alcohols has been carried out in engineered E. coli, several key problems have not been solved in earlier studies, such as the quite low production of C16/18 alcohol, the lack of optimization of the fatty alcohol biosynthesis pathway, and the uncharacterized performance of the engineered strains in scaled-up system. RESULTS: We improved the fatty alcohol production by systematically optimizing the fatty alcohol biosynthesis pathway, mainly targeting three key steps from fatty acyl-acyl carrier proteins (ACPs) to fatty alcohols, which are sequentially catalyzed by thioesterase, acyl-coenzyme A (CoA) synthase and fatty acyl-CoA reductase. By coexpression of thioesterase gene BTE, acyl-CoA synthase gene fadD and fatty acyl-CoA reductase gene acr1, 210.1?mg/L?C12/14 alcohol was obtained. A further optimization of expression level of BTE, fadD and acr1 increased the C12/14 alcohol production to 449.2?mg/L, accounting for 75.0% of the total fatty alcohol production (598.6?mg/L). In addition, by coexpression of thioesterase gene 'tesA, acyl-CoA synthase gene fadD and fatty acyl-CoA reductase gene FAR, 101.5?mg/L?C16/18 alcohol was obtained, with C16/18 alcohol accounting for 89.2% of the total fatty alcohol production. CONCLUSIONS: To our knowledge, this is the first report on selective production of C12/14 and C16/18 alcohols by microbial fermentation. This work achieved high-specificity production of both C12/14 and C16/18 alcohols. The encouraging 598.6?mg/L of fatty alcohols represents the highest titer reported so far. In addition, the 101.5?mg/L 89.2%?C16/18 alcohol suggests an important breakthrough in C16/18 alcohol production. A more detailed optimization of the expression level of fatty alcohol biosynthesis pathway may contribute to a further improvement of fatty alcohol production.

Dataset Information

Optimization of the heme biosynthesis pathway for the production of 5-aminolevulinic acid in Escherichia coli.

Publications

Optimization of the heme biosynthesis pathway for the production of 5-aminolevulinic acid in Escherichia coli.

Similar Datasets

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