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Inhibition of transformation in Streptococcus pneumoniae by lysogeny
Abstract:
Streptococcus pneumoniae R6X was lysogenized with bacteriophage 304 isolated after mitomycin induction of an ungrouped alpha-hemolytic streptococcus. Lysogenized pneumococci lost their capacity to undergo genetic transformation: transformability was restored after cells were spontaneously cured of their prophage. Both lysogens and nonlysogens produced activator substance (competence factor), and both bound deoxyribonucleic acid in a deoxyribonuclease-resistant form. However, nonlysogens retained deoxyribonucleic acid after washing, whereas lysogens did not. The latter did not liberate phage nor (unlike nonlysogens) degrade transforming deoxyribonucleic acid and contained normal levels of endonuclease.
Insights
Bacteriophage lysogenization of Streptococcus pneumoniae R6X inhibits genetic transformation. This transformation ability is restored upon prophage curing, indicating bacteriophage interference with DNA uptake or retention.
Area of Science:
- Microbiology
- Genetics
- Molecular Biology
Background:
- Streptococcus pneumoniae is a significant human pathogen.
- Genetic transformation is a key mechanism for DNA exchange in bacteria.
- Bacteriophage lysogenization can impact bacterial physiology.
Purpose of the Study:
- To investigate the effect of bacteriophage 304 lysogenization on Streptococcus pneumoniae R6X genetic transformation.
- To understand the mechanism by which lysogenization affects transformability.
Main Methods:
- Lysogenization of Streptococcus pneumoniae R6X with bacteriophage 304.
- Assessing genetic transformation efficiency before and after lysogenization and curing.
- Measuring deoxyribonucleic acid binding and retention in lysogenic and non-lysogenic cells.
- Analyzing endonuclease activity in lysogenic and non-lysogenic strains.
Main Results:
- Lysogenized pneumococci lost their genetic transformation capacity.
- Transformability was regained after spontaneous prophage curing.
- Both lysogens and non-lysogens bound deoxyribonucleic acid, but only non-lysogens retained it after washing.
- Lysogens did not degrade transforming deoxyribonucleic acid and had normal endonuclease levels.
Conclusions:
- Bacteriophage lysogenization by phage 304 inhibits Streptococcus pneumoniae genetic transformation.
- The inhibition is linked to the inability of lysogens to retain, rather than bind, exogenous deoxyribonucleic acid.
- Prophage curing restores both transformation ability and deoxyribonucleic acid retention capacity.