Excision of the lambda prophage: effects on linkage relationships of Escherichia coli chromosome.
As a result of earlier work with K12 lysogens carrying defective prophages, it was proposed that the lethal event in induction was due to interruption of the host chromosome and that the different levels of survival after induction with ultraviolet light of DNA defective mutants, in the x region, and the N, O, and P cistrons, was due to different extents of repair. To test this model, the effects of zygotic induction on the linkage between two bacterial markers, gal and bio, on either side of the lambda prophage, was examined. This linkage was destroyed after zygotic induction of mutants in the N cistron. Zygotic induction of mutants in cistron O resulted in a 5-fold depression of the linkage, while induction of mutants in cistron P and in the x region resulted in complete restoration of the linkage. The results are discussed in relation to the model of excision, and possible different extents of repair.
Eisen
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Department of Medical Biophysics and Zoology, University of Toronto, Toronto, Canada.
Tallan
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Siminovitch
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