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Lambda cin-1, a new mutation which enhances lysogenization by bacteriophage lambda, and the genetic structure of the
Genetics
|March 25, 1976
Summary
New mutations in bacteriophage lambda (cy) were mapped near the cII gene. A novel mutation, cin-1, was identified and shown to affect lysogenization, suggesting cy mutants on the right side of the map inactivate a cII/cIII binding site.
Area of Science:
- Molecular Biology
- Genetics
- Virology
Background:
- Bacteriophage lambda is a model organism for studying gene regulation and lysogeny.
- The imm434 region and cII gene are critical for lambda phage's life cycle.
- Understanding mutations affecting lysogenization is key to deciphering phage-host interactions.
Purpose of the Study:
- To map and characterize new lambda cy mutants.
- To investigate the function of the cin-1 mutation in relation to lysogenization.
- To elucidate the role of specific cy mutations in binding sites for cII/cIII proteins.
Main Methods:
- Genetic mapping using recombination frequencies to determine the location of seven lambda cy mutants.
- Fine structure mapping to precisely locate mutations within a small DNA region.
- Analysis of lysogenization efficiency in mixed infections with various mutant combinations.
Main Results:
- Seven lambda cy mutants were mapped to four sites within a 12-nucleotide pair region.
- Six mutants were localized to a 3-5 nucleotide pair segment on the right side of the cy map.
- A new mutation, cin-1, was identified and found to be cis-dominant, allowing partial lysogenization with cy, cII, or cIII mutants.
Conclusions:
- The cin-1 mutation is located 11-21 nucleotide pairs upstream of the leftmost cy mutant.
- Cy mutants on the right side of the fine structure map likely inactivate a binding site for cII/cIII proteins.
- The cy2001 mutant, located on the left side, does not appear to inactivate this binding site, indicating functional differences within the mapped region.