Lu Xiaoyun, Zhang Jinyu, Wu Qiong, Chen Guo-Qiang
Department of Biological Science and Biotechnology, Tsinghua University, Beijing 100084, PR China.
FEMS Microbiol Lett. 2003 Apr 11;221(1):97-101. doi: 10.1016/S0378-1097(03)00173-3.
Acyl-CoA dehydrogenase gene (yafH) of Escherichia coli was expressed together with polyhydroxyalkanoate synthase gene (phaC(Ac)) and (R)-enoyl-CoA hydratase gene (phaJ(Ac)) from Aeromonas caviae. The expression plasmids were introduced into E. coli JM109, DH5 alpha and XL1-blue, respectively. Compared with the strains harboring only phaC(Ac) and phaJ(Ac), all recombinant E. coli strains harboring yafH, phaC(Ac) and phaJ(Ac) accumulated at least four times more poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx). Cell dry weights produced by all recombinants containing yafH were also considerably higher than that without yafH. The addition of acrylic acid which serves as inhibitor for beta-oxidation and may lead to more precursor supply for PHA synthesis did not result in improved PHBHHx production compared with that of the overexpression of yafH. It appeared that the overexpression of acyl-CoA dehydrogenase gene (yafH) enhanced the supply of enoyl-CoA which is the substrate of (R)-enoyl-CoA hydratase. With the enhanced precursor supply, the recombinants accumulated more PHBHHx.
将大肠杆菌的酰基辅酶A脱氢酶基因(yafH)与豚鼠气单胞菌的聚羟基链烷酸酯合酶基因(phaC(Ac))和(R)-烯酰基辅酶A水合酶基因(phaJ(Ac))一起表达。分别将表达质粒导入大肠杆菌JM109、DH5α和XL1-blue。与仅携带phaC(Ac)和phaJ(Ac)的菌株相比,所有携带yafH、phaC(Ac)和phaJ(Ac)的重组大肠杆菌菌株积累的聚(3-羟基丁酸酯-co-3-羟基己酸酯)(PHBHHx)至少多四倍。所有含有yafH的重组体产生的细胞干重也明显高于不含yafH的重组体。与yafH过表达相比,添加用作β-氧化抑制剂且可能导致更多PHA合成前体供应的丙烯酸并没有提高PHBHHx的产量。似乎酰基辅酶A脱氢酶基因(yafH)的过表达增强了作为(R)-烯酰基辅酶A水合酶底物的烯酰基辅酶A的供应。随着前体供应的增加,重组体积累了更多的PHBHHx。