Alleviation of metabolic bottleneck by combinatorial engineering enhanced astaxanthin synthesis in Saccharomyces cerevisiae

Publication date: Available online 14 February 2017 Source:Enzyme and Microbial Technology Author(s): Pingping Zhou, Wenping Xie, Aipeng Li, Fan Wang, Zhen Yao, Qi Bian, Yongqiang Zhu, Hongwei Yu, Lidan Ye Highly efficient biosynthesis of the commercially valuable carotenoid astaxanthin by microbial cells is an attractive alternative to chemical synthesis and microalgae extraction. With the goal of enhancing heterologous astaxanthin production in Saccharomyces cerevisiae, metabolic engineering and protein engineering were integrated to improve both the expression and activity of rate-limiting enzymes. Firstly, to increase the supply of β-carotene as a key precursor for astaxanthin, a positive mutant of GGPP synthase (CrtE03M) was overexpressed together with three other rate-limiting enzymes tHMG1, CrtI and CrtYB. Subsequently, to accelerate the conversion of β-carotene to astaxanthin, a color screening system was developed and adopted for directed evolution of β-carotene ketolase (OBKT), generating a triple mutant OBKTM (H165R/V264D/F298Y) with 2.4-fold improved activity. After adjusting copy numbers of the above-mentioned rate-limiting enzymes to further balance the metabolic flux, a diploid strain YastD-01 was generated by mating two astaxanthin-producing haploid strains carrying the same carotenogenic pathway. Finally, further overexpression of OCrtZ and OBKTM in YastD-01 resulted in accumulation of 8.10mg/g DCW (47.18mg/l) of (3S, 3′S)-astaxanthin in shake...

Source: Enzyme and Microbial Technology - February 14, 2017 Category: Biotechnology Source Type: research