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@ARTICLE{Marienhagen:950,
      author       = {Marienhagen, J. and Eggeling, L.},
      title        = {{M}etabolic {F}unction of {C}orynebacterium glutamicum
                      {A}minotransferases {A}la{T} and {A}vt{A} and {I}mpact on
                      {L}-{V}aline {P}roduction},
      journal      = {Applied and environmental microbiology},
      volume       = {74},
      issn         = {0099-2240},
      address      = {Washington, DC [u.a.]},
      publisher    = {Soc.},
      reportid     = {PreJuSER-950},
      pages        = {7457 - 7462},
      year         = {2008},
      note         = {We thank H. Sahm and M. Bott for continuous support, K.
                      Krumbach for strain construction, and T. Bartek and C.
                      Rudolf (IBT 2, Forschungszentrum Julich, Germany) for
                      assistance with the SIXFORS fermentations.This work was
                      supported by Deutsche Bundestiftung Umwelt Projekt 13158.},
      abstract     = {Aminotransferases (ATs) interacting with L-alanine are the
                      least studied bacterial ATs. Whereas AlaT converts pyruvate
                      to L-alanine in a glutamate-dependent reaction, AvtA is able
                      to convert pyruvate to L-alanine in an L-valine-dependent
                      manner. We show here that the wild type of Corynebacterium
                      glutamicum with a deletion of either of the corresponding
                      genes does not exhibit an explicit growth deficiency.
                      However, a double mutant was auxotrophic for L-alanine,
                      showing that both ATs can provide L-alanine and that they
                      are the only ATs involved. Kinetic studies with isolated
                      enzymes demonstrate that the catalytic efficiency,
                      k(cat)/K(m), of AlaT is higher than 1 order of magnitude in
                      the direction of L-alanine formation (3.5 x 10(4) M(-1)
                      s(-1)), but no preference was apparent for AvtA, suggesting
                      that AlaT is the principal L-alanine-supplying enzyme. This
                      is in line with the cytosolic L-alanine concentration, which
                      is reduced in the exponential growth phase from 95 mM to 18
                      mM by a deletion of alaT, whereas avtA deletion decreases
                      the L-alanine concentration only to 76 mM. The combined data
                      show that the presence of both ATs has subtle but obvious
                      consequences on balancing intracellular amino acid pools in
                      the wild type. The consequences are more obvious in an
                      L-valine production strain where a high intracellular
                      drain-off of the L-alanine precursor pyruvate prevails. We
                      therefore used deletion of alaT to successfully reduce the
                      contaminating L-alanine in extracellular accumulated
                      L-valine by $80\%.$},
      keywords     = {Alanine: metabolism / Corynebacterium glutamicum:
                      enzymology / Corynebacterium glutamicum: genetics /
                      Corynebacterium glutamicum: growth $\&$ development /
                      Cytosol: chemistry / Gene Deletion / Kinetics / Pyruvic
                      Acid: metabolism / Substrate Specificity / Transaminases:
                      genetics / Transaminases: isolation $\&$ purification /
                      Transaminases: metabolism / Valine: biosynthesis / Pyruvic
                      Acid (NLM Chemicals) / Alanine (NLM Chemicals) / Valine (NLM
                      Chemicals) / Transaminases (NLM Chemicals) / J (WoSType)},
      cin          = {IBT-1},
      ddc          = {570},
      cid          = {I:(DE-Juel1)VDB55},
      pnm          = {Biotechnologie},
      pid          = {G:(DE-Juel1)FUEK410},
      shelfmark    = {Biotechnology $\&$ Applied Microbiology / Microbiology},
      typ          = {PUB:(DE-HGF)16},
      pubmed       = {pmid:18931286},
      pmc          = {pmc:PMC2607172},
      UT           = {WOS:000261513700001},
      doi          = {10.1128/AEM.01025-08},
      url          = {https://juser.fz-juelich.de/record/950},
}