Genetic analysis of prophage effects on heteroimmune superin fection in Serratia marcescens
✍ Scribed by Prof. Dr. H. Steiger
- Publisher
- John Wiley and Sons
- Year
- 2007
- Tongue
- English
- Weight
- 744 KB
- Volume
- 21
- Category
- Article
- ISSN
- 0233-111X
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✦ Synopsis
Abstract
Plaque formation of phage χ on Serratia marcescens strain HY normally depends on the presence of either a ψ or y prophage in the indicator bacteria. Bacterial ink mutants allowing χ growth in the absence of either prophage were isolated from the doubly cured strain HY (ψ, y)^−^. By means of a χ mutant, named gdy, an active participation of χ in antagonizing inhibition of its own growth on HY (ψ, y)^−^) was demonstrated. The gdy mutation is closely linked to gene c~III~ coding for the χ repressor. The prophages ψ and y enable χ to grow undisturbed probably by modifying the χ DNA during replication in such a way that it is not susceptible to the ink^+^ effect. Whereas χ grown on HY (ψ, y)^−^ink^−^ gave only rare productive infections of HY (ψ, y)^−^, ψ and y grown on the same strain were fully infective.
The interference exerted by a χ prophage on vegetative propagation of y is based upon a multicomponent mechanism, the interference being removed, or diminished by mutations residing either inside or outside of the χ prophage. The responsible phage gene iny^+^ is dominant over its mutant allele iny^−^; hence it codes for a diffusible product. Both on the vegetative and the prophage genome iny is located near gene l~I~ responsible for lysogenic conversion of bacteria to non‐adsorption of χ.
The restriction‐modification system of HY is not involved in the growth inhibition of χ by HY (ψ, y)^−^. Contrary to the other phages used in this work y is refractory to restriction.