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Following Cell-fate in E. coli After Infection by Phage Lambda
Published on: October 14, 2011
Infectivity of lambda heteroduplex deoxyribonucleic acid molecules
Abstract:
Heteroduplex deoxyribonucleic acid (DNA) molecules were formed in vitro by denaturing and renaturing a mixture of DNAs from a variety of lambda strains. The infectivity of these heteroduplexes was studied by using host-controlled modification and restriction to prevent infection by contaminating parental homoduplexes. Either strand was able to protect against degradation by restriction nucleases in vivo. A large proportion of progeny phage, which had been produced after infection with heteroduplexes containing noncomplementary base pairs at multiple loci, retained the genotype of one of the parental homoduplexes. The results indicate that conversion of heteroduplexes to homoduplexes in vivo by a DNA repair mechanism does not occur frequently. Molecules heterozygous for the c17 or vir operator mutations were not infectious; it is suggested that these mutations involve multiple base pairs.
Insights
This study shows that DNA repair does not frequently convert heteroduplex DNA to homoduplex DNA in vivo. Most progeny phage retained parental genotypes after infection with mixed DNA molecules.
Area of Science:
- Molecular Biology
- Genetics
- Virology
Background:
- Heteroduplex deoxyribonucleic acid (DNA) molecules are formed by combining DNA strands from different sources.
- Understanding DNA repair mechanisms is crucial for comprehending genetic stability and evolution.
Purpose of the Study:
- To investigate the infectivity of in vitro formed heteroduplex DNA molecules.
- To determine the frequency of DNA repair converting heteroduplexes to homoduplexes in vivo.
Main Methods:
- Formation of heteroduplex DNA from various lambda phage strains.
- Utilizing host-controlled modification and restriction to isolate heteroduplex infectivity.
- Analyzing progeny phage genotypes after infection with heteroduplex DNA.
Main Results:
- Both DNA strands of heteroduplexes provided protection against restriction nucleases in vivo.
- A significant proportion of progeny phage inherited parental genotypes from heteroduplex infections.
- Molecules with operator mutations (c17, vir) were non-infectious, suggesting they involve multiple base pairs.
Conclusions:
- DNA repair mechanisms do not frequently convert heteroduplexes to homoduplexes in vivo.
- The infectivity of heteroduplex DNA is influenced by the presence of non-complementary base pairs and specific mutations.
