Journal of Industrial Microbiology & Biotechnology

, Volume 42, Issue 11, pp 1547–1556

Control of carbon flux to glutamate excretion in Klebsiella pneumoniae: the role of the indigenous plasmid and its encoded isocitrate dehydrogenase

  • Mansi El-Mansi
  • Francois Trappey
  • Ewan Clark
  • Malcolm Campbell
Metabolic Engineering and Synthetic Biology

DOI: 10.1007/s10295-015-1689-3

Cite this article as:
El-Mansi, M., Trappey, F., Clark, E. et al. J Ind Microbiol Biotechnol (2015) 42: 1547. doi:10.1007/s10295-015-1689-3

Abstract

Klebsiella pneumoniae (NCTC, CL687/80) harbors a large indigenous plasmid (pC3), which in addition to encoding for citrate utilization, proline synthesis and glutamate excretion, it uniquely carries the structural gene (icd); encoding isocitrate dehydrogenase (ICDH). Flux analysis revealed that ICDH, despite its role in the generation of NADPH required for glutamate dehydrogenase, is not rate-limiting (controlling) in central metabolism as evidenced by a negative flux control coefficient and an adverse effect of overexpression (14-fold) on glutamate excretion. More significantly, however, this paper presents, for the first time, clear evidence that the accumulation of glutamate and its subsequent excretion is associated with the C3 plasmid-encoded regulatory elements, which trigger a shift-down in the activity of α-ketoglutarate dehydrogenase, both in the K. pneumoniae parental strain as well as in the E. coli exconjugants strains. This finding opens the door for the exploitation of regulatory elements as a tool for manipulating flux in microbial cell factories.

Keywords

Klebsiella pneumoniae Glutamate excretion Isocitrate dehydrogenase Glutamate dehydrogenase α-Ketoglutarate dehydrogenase 

Copyright information

© Society for Industrial Microbiology and Biotechnology 2015

Authors and Affiliations

  • Mansi El-Mansi
    • 1
  • Francois Trappey
    • 2
  • Ewan Clark
    • 3
  • Malcolm Campbell
    • 2
    • 4
  1. 1.Centre for Research and Innovation, Faculty of ScienceElizade UniversityAkureNigeria
  2. 2.Department of BiologyDavidson CollegeDavidsonUSA
  3. 3.Institute of Cell BiologyUniversity of EdinburghEdinburghScotland, UK
  4. 4.Genome Consortium for Active TeachingDavidsonUSA