Metabolic engineering using iterative self-cloning to improve lipid productivity in Coccomyxa

Abstract We previously developed a self-cloning system that introduces cDNA of the uridine monophosphate synthase gene (cUMPS) of Coccomyxa sp. strain Obi as a selectable marker into uracil-auxotrophic mutants (Ura−) of the same alga. Here, we developed a Cre/loxP-based system for the removal of cUM...

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Autores principales: Yuki Kasai, Takuya Tsukahara, Fukiko Ikeda, Yoko Ide, Shigeaki Harayama
Formato: article
Lenguaje:EN
Publicado: Nature Portfolio 2018
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Acceso en línea:https://doaj.org/article/8ba167cf36e2418999530200e8cb775f
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Sumario:Abstract We previously developed a self-cloning system that introduces cDNA of the uridine monophosphate synthase gene (cUMPS) of Coccomyxa sp. strain Obi as a selectable marker into uracil-auxotrophic mutants (Ura−) of the same alga. Here, we developed a Cre/loxP-based system for the removal of cUMPS flanked by directly repeated loxP sites from the Coccomyxa genome using the intracellular delivery of purified Cre recombinase to generate an Ura− strain that was used as a host for second-round transformation using cUMPS as the selection marker. Employing this marker–gene-recycling system, Coccomyxa strains devoid of foreign DNA except the 34-bp loxP sequence, which overexpressed an acyl-(acyl-carrier-protein) thioesterase gene, and a type-2 diacylglycerol acyltransferase gene, were constructed by the sequential introduction of two expression cassettes for the respective genes. One of the resulting strains showed 1.4-fold higher lipid productivity than the wild-type strain. This method will be applicable to other eukaryotic microalgae to create marker-free transgenic strains.