Reduced transaminase B (IlvE) activity caused by the lack of yjgF is dependent on the status of threonine deaminase (IlvA) in Salmonella enterica serovar Typhimurium

J Bacteriol. 2004 Feb;186(3):803-10. doi: 10.1128/JB.186.3.803-810.2004.


The YjgF/YER057c/UK114 family is a highly conserved class of proteins that is represented in the three domains of life. Thus far, a biochemical function demonstrated for these proteins in vivo or in vitro has yet to be defined. In several organisms, strains lacking a YjgF homolog have a defect in branched-chain amino acid biosynthesis. This study probes the connection between yjgF and isoleucine biosynthesis in Salmonella enterica. In strains lacking yjgF the specific activity of transaminase B, catalyzing the last step in the synthesis of isoleucine, was reduced. In the absence of yjgF, transaminase B activity could be restored by inhibiting threonine deaminase, the first enzymatic step in isoleucine biosynthesis. Strains lacking yjgF showed an increased sensitivity to sulfometruron methyl, a potent inhibitor of acetolactate synthase. Based on work described here and structural reports in the literature, we suggest a working model in which YjgF has a role in protecting the cell from toxic effects of imbalanced ketoacid pools.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Bacterial Proteins / physiology*
  • Butyrates / pharmacology
  • Isoleucine / pharmacology
  • Operon
  • Salmonella typhimurium / enzymology*
  • Sulfonylurea Compounds / pharmacology
  • Threonine Dehydratase / physiology*
  • Transaminases / metabolism*


  • Bacterial Proteins
  • Butyrates
  • Sulfonylurea Compounds
  • YjgF protein, Bacteria
  • YjgF protein, Salmonella typhimurium
  • Isoleucine
  • alpha-ketobutyric acid
  • Transaminases
  • branched-chain-amino-acid transaminase
  • Threonine Dehydratase
  • sulfometuron methyl