Mechanism of Activation of Catabolite-Sensitive Genes: A Positive Control System*

  1. Geoffrey Zubay†,
  2. Daniele Schwartz‡, and
  3. Jon Beckwith‡
  1. COLUMBIA UNIVERSITY, NEW YORK, NEW YORK
  2. HARVARD MEDICAL SCHOOL, BOSTON, MASSACHUSETTS

Abstract

Catabolite repression is defined as the inhibition of enzyme induction by glucose or related substances. In the bacterium E. coli, the effect of glucose appears to be due to a lowering of the cyclic AMP level. A DNA-directed cell-free system for β-galactosidase synthesis has served as a model system for studying the mechanism of action of cyclic AMP. Previously, it was reported that in this system cyclic AMP is required for normal initiation of mRNA synthesis. A protein factor which acts in conjunction with the cyclic AMP has been partially purified. This protein factor has a high affinity for cyclic AMP. These and other results presented herein lead us to the conclusion that cyclic AMP and a protein factor called the catabolite gene activator protein are part of a positive control system for activating catabolite-sensitive genes.

Footnotes

  • ↵ † Department of Biological Sciences, Columbia University, New York, N.Y.

  • ↵ ‡ Department of Bacteriology and Immunology, Harvard Medical School, Boston, Mass.

  • ↵ * This work was supported by grants from the National Institute of Health, 5-RO1-GM-16648-02, and the American Cancer Society, E-545.

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  1. PNAS 1970-05 vol. 66 no. 1 104-110
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