title: [Effect of phosphoenolpyruvate carboxylase gene knock-out on metabolism in Corynebacterium pekinense PD-67].
abstract: OBJECTIVE
  In order to optimize precursor supply for L-tryptophan biosynthesis, a Corynebacterium pekinense PD-67 mutant with phosphoenolpyruvate carboxylase gene (ppc) in-frame deletion was constructed. The effect of ppc knock-out on physiological characteristics of the mutant was investigated.
  
  
  METHODS
  The upstream and downstream fragments of ppc were cloned from C. pekinense PD-67 chromosome and ligated to integration vector. The mutant C. pekinense PD-67-deltappc was screened by homologous recombination. The physiological characteristics of the mutant were investigated by fermentation experiments and measurement of pyruvate carboxylase (PCx) and pyruvate kinase (PK).
  
  
  RESULTS
  The mutant with ppc gene in-frame deletion was screened and confirmed by PCR check and phosphoenolpyruvate carboxylase determination. The mutant exhibited slow growth and less cell mass, 80% as much as the parent strain. The ppc knock-out resulted in decrease of L-tryptophan accumulation and overproduction of pyruvate-related amino acids, which accompanied by increase of PK activity and the decrease of PCx activity, in C. pekinense PD-67.
  
  
  CONCLUSIONS
  The knock-out of ppc gene affected the metabolism of the strain to some extent. Only by blocking the anaplerotic pathway PEPCx participated was insufficient to increase the accumulation of L-tryptophan in C. pekinense PD-67.
authors.affiliation: Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China. lumintao@126.com
authors.forename: Mintao
authors.initials: M
authors.lastname: Lu
authors.forename: Zhi
authors.initials: Z
authors.lastname: Zhao
authors.forename: Yingzi
authors.initials: Y
authors.lastname: Zhang
authors.forename: Yu
authors.initials: Y
authors.lastname: Wang
authors.forename: Jiuyuan
authors.initials: J
authors.lastname: Ding
mesh_terms: D003352:Corynebacterium / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D005285:Fermentation / Q000502:physiology; D055786:Gene Knockout Techniques; D005798:Genes, Bacterial / Q000502:physiology*; D008969:Molecular Sequence Data; D010730:Phosphoenolpyruvate Carboxylase / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011766:Pyruvate Carboxylase / Q000235:genetics* / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism*
chemical_list: D014364:Tryptophan; D010730:Phosphoenolpyruvate Carboxylase; D011766:Pyruvate Carboxylase