title: Co-expression of five genes in E coli for L-phenylalanine in Brevibacterium flavum.
abstract: OBJECTIVE
  To study the effect of co-expression of ppsA, pckA, aroG, pheA and tyrB genes on the production of L-phenylalanine, and to construct a genetic engineering strain for L-phenylalanine.
  
  
  METHODS
  ppsA and pckA genes were amplified from genomic DNA of E. coli by polymerase chain reaction, and then introduced into shuttle vectors between E coli and Brevibacterium flavum to generate constructs pJN2 and pJN5. pJN2 was generated by inserting ppsA and pckA genes into vector pCZ; whereas pJN5 was obtained by introducing ppsA and pckA genes into pCZ-GAB, which was originally constructed for co-expression of aroG, pheA and tyrB genes. The recombinant plasmids were then introduced into B. flavum by electroporation and the transformants were used for L-phenylalanine fermentation.
  
  
  RESULTS
  Compared with the original B. flavum cells, all the transformants were showed to have increased five enzyme activities specifically, and have enhanced L-phenylalanine biosynthesis ability variably. pJN5 transformant was observed to have the highest elevation of L-phenylalanine production by a 3.4-fold. Co-expression of ppsA and pckA increased activity of DAHP synthetase significantly.
  
  
  CONCLUSIONS
  Co-expression of ppsA and pckA genes in B. flavum could remarkably increase the expression of DAHP synthetase; Co-expression of ppsA, pckA, aroG, pheA and tyrB of E. coli in B. flavum was a feasible approach to construct a strain for phenylalanine production.
authors.affiliation: Department of Microbiology, School of Life Science, Fudan University, 220 Han Dan Road, Shanghai 200433, China.
authors.forename: Yong-Qing
authors.initials: YQ
authors.lastname: Wu
authors.forename: Pei-Hong
authors.initials: PH
authors.lastname: Jiang
authors.forename: Chang-Sheng
authors.initials: CS
authors.lastname: Fan
authors.forename: Jian-Gang
authors.initials: JG
authors.lastname: Wang
authors.forename: Liang
authors.initials: L
authors.lastname: Shang
authors.forename: Wei-Da
authors.initials: WD
authors.lastname: Huang
mesh_terms: D001951:Brevibacterium / Q000235:genetics* / Q000378:metabolism; D004926:Escherichia coli / Q000235:genetics*; D015870:Gene Expression / Q000502:physiology*; D010649:Phenylalanine / Q000096:biosynthesis / Q000235:genetics*
chemical_list: D010649:Phenylalanine