Gosset G, Yong-Xiao J, Berry A
Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Morelos, México.
J Ind Microbiol. 1996 Jul;17(1):47-52. doi: 10.1007/BF01570148.
Different approaches to increasing carbon commitment to aromatic amino acid biosynthesis were compared in isogenic strains of Escherichia coli. In a strain having a wild-type PEP:glucose phosphotransferase (PTS) system, inactivation of the genes encoding pyruvate kinase (pykA and pykF) resulted in a 3.4 fold increase in carbon flow to aromatic biosynthesis. In a strain already having increased carbon flow to aromatics by virtue of overexpression of the tktA gene (encoding transketolase), the pykA and/or pykf mutations had no effect. A PTS- glucose+ mutant showed a 1.6-fold increase in carbon flow to aromatics compared to the PTS+ control strain. In the PTS- glucose+ host background, overexpression of tktA caused a further 3.7-fold increase in carbon flow, while inactivation of pykA and pykF caused a 5.8-fold increase. When all of the variables tested (PTS-glucose+, pykA, pykF, and overexpressed tktA) were combined in a single strain, a 19.9-fold increase in carbon commitment to aromatic biosynthesis was achieved.
在大肠杆菌的同基因菌株中，比较了增加碳对芳香族氨基酸生物合成贡献的不同方法。在具有野生型磷酸烯醇式丙酮酸：葡萄糖磷酸转移酶（PTS）系统的菌株中，编码丙酮酸激酶（pykA和pykF）的基因失活导致流向芳香族生物合成的碳流量增加了3.4倍。在一个由于tktA基因（编码转酮醇酶）过表达而已经增加了流向芳香族化合物碳流量的菌株中，pykA和/或pykF突变没有影响。与PTS +对照菌株相比，PTS -葡萄糖+突变体流向芳香族化合物的碳流量增加了1.6倍。在PTS -葡萄糖+宿主背景下，tktA的过表达使碳流量进一步增加了3.7倍，而pykA和pykF的失活使碳流量增加了5.8倍。当所有测试变量（PTS -葡萄糖+、pykA、pykF和过表达的tktA）组合在一个菌株中时，碳对芳香族生物合成的贡献增加了19.9倍。
