Cloning and characterization of the Escherichia coli K-12 alanine-valine transaminase (avtA) gene

J Bacteriol. 1987 Sep;169(9):4228-34. doi: 10.1128/jb.169.9.4228-4234.1987.


avtA, which encodes the alanine-valine transaminase, transaminase C, was cloned in vivo with high- and low-copy-number mini-Mu cloning vectors. The phenotype conferred by the cloned avtA+ gene usually depended upon the plasmid copy number; most high-copy-number avtA+ plasmids permitted isoleucine-requiring ilvE strains to grow in the absence of isoleucine (multicopy suppression), while low-copy-number avtA+ plasmids did not. avtA was mapped to a 1.25-kilobase segment by comparison of the restriction maps of 24 independent mini-Mu plasmids and then by gamma-delta (Tn1000) mutagenesis of a pBR322-avtA+ plasmid. The direction of transcription of avtA on the cloned fragment was determined with fusions to a promoterless lac gene.

Publication types

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

MeSH terms

  • Chromosome Mapping
  • Cloning, Molecular
  • DNA Restriction Enzymes
  • DNA Transposable Elements
  • Escherichia coli / enzymology
  • Escherichia coli / genetics*
  • Gene Expression Regulation
  • Genes, Bacterial*
  • Mutation
  • Phenotype
  • Plasmids
  • Transaminases / biosynthesis
  • Transaminases / genetics*
  • Transcription, Genetic
  • Transduction, Genetic


  • DNA Transposable Elements
  • Transaminases
  • valine-pyruvate transaminase
  • DNA Restriction Enzymes