Molecular and General Genetics MGG

, Volume 148, Issue 3, pp 271–279

Conditional lethal phosphatidylserine decarboxylase mutants of Escherichia coli

Mapping of the structural gene for phosphatidylserine decarboxylase
  • Edward Hawrot
  • Eugene P. Kennedy

DOI: 10.1007/BF00332901

Cite this article as:
Hawrot, E. & Kennedy, E.P. Molec. Gen. Genet. (1976) 148: 271. doi:10.1007/BF00332901


The final step in the biosynthesis of phosphatidylethanolamine, the major membrane lipid of Escherichia coli, is catalyzed by the membrane-bound enzyme, phosphatidylserine decarboxylase. A variation of a procedure for localized mutagenesis (Hong and Ames, 1971) was employed to generate conditional lethal mutants in phosphatidylserine decarboxylase. In our modification, an episome carrying the psd gene closely linked to purA+ was heavily mutagenized in vivo in a strain also lysogenic for phage P1 CMclr100. After induction of a phage lytic cycle, the purA+ marker was transduced to a purA- recipient. A majority of the Pur+ transductants thus contained a psd gene originating from the heavily mutagenized episomal strain. Three mutants were isolated in which temperature-sensitive growth is caused by thermosensitive phosphatidylserine decarboxylase activity that is defective in vivo at the non-permissive temperature. All 3 mutations were mapped at the same location as psd1, being cotransduced with melA, purA, and ampA. The gene order in this region, as determined by a phage P1-mediated, three-factor cross is ampA-psd-purA. psd+ is dominant to the psd mutant alleles.

Copyright information

© Springer-Verlag 1976

Authors and Affiliations

  • Edward Hawrot
    • 1
  • Eugene P. Kennedy
    • 1
  1. 1.Department of Biological ChemistryHarvard Medical SchoolBostonUSA

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