Isolation, characterization, and mapping of Escherichia coli mutants blocked in the synthesis of ornithine decarboxylase Academic Article uri icon


MeSH Major

  • Carboxy-Lyases
  • Escherichia coli
  • Mutation
  • Ornithine Decarboxylase


  • Several Escherichia coli K-12 mutants blocked in the synthesis of ornithine decarboxylase (OD) were isolated after transduction for serA+ in a strain (MA197) blocked in agmatine ureohydrolase (AUH) with a mutagenized phage lysate of P1. The new double-polyamine mutants were characterized by an unconditional polyamine dependence; either putrescine or spermidine was required for normal growth. The mutational block was varified by the demonstration of a virtual absence of OD activity in cellular extracts. The mutation, designated speC, was mapped by P1 transduction in several strains and was shown to have a cotransduction frequency of 17.2% with serA. Map order was established as serA speB speC metK. A derivative of one of the OD mutants having wild-type levels of AUH and blocked in OD was utilized along with an OD AUH mutant and an OD+ AUH strain to explore the phenomenon of "pathway selection" using growth rate as a parameter. Polyamine pool studies were carried out simultaneously. The results presented here support the hypothesis of pathway selection, implying a preferential utilization of exogenous arginine rather than endogenously produced arginine in polyamine biosynthesis.

publication date

  • December 1975



  • Academic Article



  • eng

PubMed Central ID

  • PMC235969

PubMed ID

  • 1102531

Additional Document Info

start page

  • 791

end page

  • 9


  • 124


  • 2