L-asparagine uptake in Escherichia coli

J Bacteriol. 1975 Sep;123(3):937-45. doi: 10.1128/jb.123.3.937-945.1975.


The uptake of L-asparagine by Escherichia coli K-12 is characterized by two kinetic components with apparent Km values of 3.5 muM and 80 muM. The 3.5 muM Km system displays a maximum velocity of 1.1 nmol/min per mg of protein, which is a low value when compared with derepressed levels of other amino acid transport systems but is relatively specific for L-asparagine. Compounds providing effective competition for L-asparagine uptake were 4-carbon analogues of the L-isomer with alterations at the beta-amide position, i.e., 5-diazo-4-oxo-L-norvaline (Ki = 4.6 muM), beta-hydroxyamyl-L-aspartic acid (Ki = 10 muM), and L-aspartic acid (Ki = 50 muM). Asparagine uptake is energy dependent and is inhibited by a number of metabolic inhibitors. In a derived strain of E. coli deficient in cytoplasmic asparaginase activity asparagine can be accumulated several-fold above the apparent biosynthetic pool of the amino acid and 100-fold above the external medium. The high affinity system is repressed by culture of cells with L-asparagine supplements in excess of 1 mM and is suggested to be necessary for growth of E. coli asparagine auxotrophs with lower supplement concentrations.

Publication types

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

MeSH terms

  • Asparagine / analogs & derivatives
  • Asparagine / metabolism*
  • Binding, Competitive
  • Biological Transport, Active / drug effects
  • Dose-Response Relationship, Drug
  • Escherichia coli / metabolism*
  • Glucose / metabolism
  • Hydrogen-Ion Concentration
  • Kinetics
  • Lactates / metabolism
  • Malonates / pharmacology
  • Oxalates / pharmacology
  • Oxamic Acid / pharmacology
  • Sodium / pharmacology
  • Structure-Activity Relationship
  • Succinates / metabolism
  • Temperature


  • Lactates
  • Malonates
  • Oxalates
  • Succinates
  • Asparagine
  • Sodium
  • Glucose
  • Oxamic Acid