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Interference in bacteriophage growth by a resident plasmid lambda dv. II. Role of the promoter-operator
Abstract:
The susceptibilities to interference by lambdadv of a set of lambda phages differing in the genetic structure of their right promoter-operator (pRoR) were compared. For this purpose mutant phages were added to lambdadv-carrier cells at various multiplicities, and abilities to escape from interference, as represented by percentages of infected complexes to produce progeny phages, were compared. It was observed that phages that carry strongly constitutive pRoR were able to escape from interference at a low multiplicity of infection, whereas phages with weakly constitutive pRoR were able to escape only when a large number of these genomes entered into a cell. Several mutations in the pRoR were arranged in order of their constitutivity, or ability to escape from interference. Next, the abilities of a set of lambdadv plasmids differing in their pRoR to cause interference were compared. The results showed that interference increased with increase in constitutivity of the pRoR in the plasmid genome. These observations are thought to reflect a regulatory system of the plasmid replicon, and a possible mechanism for the system is discussed.
Insights
Bacteriophage lambda (λ) promoter-operator (pRoR) mutations affect interference. Constitutive pRoR mutations in lambda phages and plasmids influence their ability to escape or cause interference, revealing insights into plasmid replicon regulation.
Area of Science:
- Molecular Biology
- Virology
- Genetics
Background:
- Bacteriophage lambda (λ) utilizes a promoter-operator region (pRoR) for gene regulation.
- Understanding interference mechanisms is crucial for phage-host interactions and genetic manipulation.
Purpose of the Study:
- To compare the interference susceptibility of lambda phages with varying right promoter-operator (pRoR) genetic structures.
- To investigate the relationship between pRoR constitutivity and interference in lambda phage and plasmid systems.
Main Methods:
- Comparative analysis of lambda phage mutant susceptibility to lambdadv interference.
- Assessment of phage escape from interference based on progeny production at different multiplicities of infection.
- Evaluation of lambdadv plasmid interference capabilities correlated with pRoR constitutivity.
Main Results:
- Lambda phages with highly constitutive pRoR escaped lambdadv interference more readily at low multiplicities.
- Phages with weakly constitutive pRoR required higher multiplicities to escape interference.
- Increased pRoR constitutivity in lambdadv plasmids correlated with enhanced interference.
Conclusions:
- pRoR genetic structure significantly impacts lambda phage and plasmid interference dynamics.
- The findings suggest a regulatory system for the plasmid replicon influenced by pRoR activity.
- A potential mechanism for this regulatory system is proposed and discussed.