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The lactose system in Klebsiella aerogenes V9A: 3. Specific repression of the lac operon by melibiose and raffinose

Published online by Cambridge University Press:  14 April 2009

E. C. R. Reeve
Affiliation:
Institute of Animal Genetics, West Mains Road, Edinburgh EH9 3JN, Scotland
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Summary

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In Klebsiella aerogenes strain V9A melibiose and raffinose fail to induce the lac operon and strongly repress its induction by isopropyl-β-d-thiogalactopyranoside (IPTG). This repression is specific to the lac system and is not released by cAMP, which releases the catabolite repression exerted by glucose and sucrose. It is concluded that melibiose and raffinose bind to the lac repressor molecule in Klebsiella V9A, competitively displacing IPTG, and that the resulting complex is able to repress the lac operon. Other Klebsiella strains tested show the same repression phenomenon.

Type
Short Papers
Copyright
Copyright © Cambridge University Press 1973

References

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