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Effects of DNA heterologies on bacteriophage lambda recombination
1Department of Biology, Massachusetts Institute of Technology, Cambridge, 02139, USA.
Genetics
|January 1, 1988
Summary
Bacteriophage lambda recombination can accommodate small DNA sequence differences up to 19 base pairs. Larger heterologies (≥26 bp) result in viable phage particles that fail to encapsulate, hindering heterozygous progeny observation.
Area of Science:
- Molecular Biology
- Genetics
- Virology
Background:
- Previous studies suggested bacteriophage lambda recombination can involve heteroduplex DNA with sequence nonhomologies.
- Direct observation of heterozygous progeny phage containing these heterologies has been lacking.
Purpose of the Study:
- To investigate the direct accommodation of small insertion and deletion mutations in bacteriophage lambda recombination.
- To determine the maximum size of sequence nonhomology that can be present in heterozygous progeny phage.
Main Methods:
- Constructed small insertion and deletion mutations within the cI gene of bacteriophage lambda.
- Performed genetic crosses between lambda cI- Oam29 and lambda cI+ Pam80 under replication-restricted conditions.
- Selected and tested recombinant progeny for cI heterozygosity.
Main Results:
- Heterozygous bacteriophage lambda recombinants were readily observed with insertions of 4 to 19 base pairs (bp) in the cI gene.
- Nonhomologies of at least 19 bp were successfully accommodated in heteroduplex DNA during lambda recombination.
- Few selected recombinants were heterozygous for cI when mutations of 26 bp or larger were present.
Conclusions:
- Bacteriophage lambda recombination can accommodate sequence nonhomologies up to 19 bp within heteroduplex DNA.
- Larger heterologies (≥26 bp) lead to a failure in encapsulating DNA into viable phage particles, not a failure in recombination itself.