Genetic manipulations restored the growth fitness of reduced-genome Escherichia coli

详细信息    查看全文

• 作者：Yasutaka Hirokawa¹ ; ^§ ; ; Hiroaki Kawano¹ ; ^§ ; § ; ; Kimie Tanaka-Masuda¹ ; Noriko Nakamura¹ ; ^§ ; § ; § ; ; Akira Nakagawa¹ ; ^§ ; § ; § ; § ; ; Mikito Ito¹ ; ^§ ; § ; § ; § ; § ; ; Hideo Mori¹ ; ^{h2mori@jst.go.jp} ; ^{hideo.mori@live.jp} ; ^{hideo.mori@kyowa-kirin.co.jp} ; Taku Oshima² ; Naotake Ogasawara²
• 关键词：Escherichia coli ; Genome reduction ; Metabolic engineering ; Synthetic biology ; Molecular breeding
• 刊名：Journal of Bioscience and Bioengineering
• 出版年：2013
• 出版时间：July, 2013
• 年：2013
• 卷：116
• 期：1
• 页码：52-58
• 全文大小：513 K

文摘

Microbes with smaller genomes would be better chassis for analysis, design, and improvement in the fields of metabolic engineering, synthetic biology, and molecular breeding. To create an Escherichia coli strain with a smaller genome, we used a stepwise genome reduction approach. Beginning with strain MGF-01, which has a genome of 3.62 megabase pairs (Mbp), we generated two E. coli K-12 strains without any insertion sequence (IS), DGF-327 and DGF-298, with reduced genome sizes of 3.27 and 2.98?Mbp, respectively. During the strain construction, intrinsic mutations of ilvG and rph were functionally restored to accelerate initial growth after inoculation. The genomes of the two strains were sequenced, and their structures were confirmed. Both strains showed no auxotrophy, and had better growth fitness, especially in the initial phase, and better cell yield in a rich medium than the wild type K-12 strain. Transcriptome analysis revealed that ibpAB and lon, which encode a heat-shock chaperone and a protease for abnormal proteins, respectively, are down-regulated in DGF strains, compared to the ancestral strains with larger genomes. We concluded that down-regulation of the genes encoding chaperones and proteases is one of the factors that improve the fitness of DGF strains. The DGF strains with fewer genes and better cell yield will be good hosts for applications.