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Rearrangements between the operators in the bacteriophage lambda
Molecular & General Genetics : MGG
|January 1, 1985
Summary
Lambda phage operator mutations impact infection efficiency. A specific inversion in the lambda iri mutant restores left operon control, enabling proper infection through altered repressor binding.
Area of Science:
- Molecular Biology
- Bacteriology
- Genetics
Background:
- The left operator mutant lambda v2s exhibits impaired development during infection due to uncontrolled left operon expression.
- Bacteriophage lambda's regulatory regions, including operators OL and OR, are crucial for controlling gene expression and infection cycles.
Purpose of the Study:
- To investigate the genetic basis of a revertant mutant (lambda iri) that overcomes the developmental defect of lambda v2s.
- To elucidate the mechanism by which the lambda iri mutation restores proper regulation of the left operon.
Main Methods:
- Genetic analysis of lambda v2s and its revertant lambda iri.
- Characterization of operator mutations and sequence rearrangements using molecular techniques.
- Assessment of phage development and gene expression during infection.
Main Results:
- The lambda iri revertant contains an inversion within the cI region, spanning the lambda operators OL and OR.
- Formation of this inversion is linked to a translocation of right operator (OR) mutant sequence to the left operator (OL) in the lambda v2s mutant.
- The inverted OR sequence at the OL position in lambda iri restores functional repression of the left operon by the lambda cro repressor.
Conclusions:
- The specific inversion in lambda iri corrects the constitutive left operon expression seen in lambda v2s.
- This genetic rearrangement highlights the critical role of operator sequences and their positioning in bacteriophage lambda gene regulation and infection viability.