Temperature-Sensitive Mutants of Escherichia coli Requiring Saturated and Unsaturated Fatty Acids for Growth: Isolation and Properties

  1. Mark E. Harder*,
  2. Ifor R. Beacham*,
  3. John E. Cronan, Jr.,
  4. Kathryn Beacham*,
  5. Joy L. Honegger*, and
  6. David F. Silbert*,
  1. *Department of Biological Chemistry, Washington University School of Medicine, St. Louis, Missouri 63110
  2. Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut 06510

Abstract

A procedure is described for selection of temperature-sensitive mutants affecting fatty-acid synthesis based upon radiation suicide of wild-type organisms by tritiated acetate selectively incorporated into fatty acids. At 37°, two of the mutants extensively incorporate fatty-acid supplements provided in the medium, and grow for extended periods only when a trans-unsaturated or a combination of saturated and cis-unsaturated fatty acids is available. In vivo fatty-acid synthesis, measured by [14C]acetate incorporation, is temperature-sensitive in these strains relative to protein synthesis and other non-lipid macromolecular syntheses using acetate. The biochemical nature of these mutations has not been identified.

Footnotes

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