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The lactose system in Klebsiella aerogenes V9A: 4. A comparison of the lac operons of Klebsiella and Escherichia coli

Published online by Cambridge University Press:  14 April 2009

E. C. R. Reeve  and
J. A. Braithwaite
E. C. R. Reeve
Affiliation:
Institute of Animal Genetics, West Mains Road, Edinburgh, EH9 3JN, Scotland
J. A. Braithwaite
Affiliation:
Institute of Animal Genetics, West Mains Road, Edinburgh, EH9 3JN, Scotland
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Klebsiella aerogenes V9A contains two lac operons, one chromosomal and one borne by the Lac plasmid, FKlac. It is shown that the plasmid Lac repressor resembles that of Esherichia coli in that it represses the E. coli operon but is inactivated by melibiose. In contrast, the chromosomal Lac repressor of V9A is unable to repress the E. coli operon or the FKlac operon, but is converted into an active repressor of both these operons on becoming bound to melibiose. The chromosomal Lac repressor is able to repress its own operon whether or not it is bound to melibiose, but is inactivated by isopropyl-β-D-thiogalactoside. These results support the hypothesis that the Klebsiella Lac plasmid was derived from an ancestral E. coli chromosome.

Type
Research Article
Information
Genetics Research , Volume 24 , Issue 3 , December 1974 , pp. 323 - 331
Copyright
Copyright © Cambridge University Press 1974

References

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