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Mechanism of phage-induced lysis in pneumococci
Abstract:
Earlier studies have suggested the possible role of host autolytic enzyme in the release of progeny phage from Dp-1 infected pneumococci. Several new experiments described here reinforce this notion. Specifically, the resistance of an autolysis-defective mutant to infection at low phage to cell ratios could be eliminated by prior 'coating' of the host bacteria with pneumococcal autolysin isolated from wild-type cells. Similar, productive infection was also possible by lowering the temperature of incubation to 30 degrees C, a condition that leads to a partial activation of the thermosensitive residual autolysin in the mutant cells. Other experiments, however, clearly indicate the role of the newly discovered phage-associated lysin (PAL), reported in the accompanying communication, in bacteriophage release and culture lysis; specifically, lysis was stimulated by reducing agents and inhibited by cardiolipin. It seems that both the host-related and the PAL activities are involved with Dp-1 induced lysis of pneumococci.
Insights
Host autolytic enzymes and phage-associated lysin (PAL) both contribute to Dp-1 phage release from pneumococci. Modifying host autolysin activity impacts phage infection efficiency, highlighting a dual mechanism in bacterial lysis.
Area of Science:
- Microbiology
- Bacteriology
- Molecular Biology
Background:
- Previous research suggested host autolytic enzymes facilitate progeny phage release in Dp-1 infected pneumococci.
- Autolysis is a critical process in the bacterial life cycle and phage-host interactions.
Purpose of the Study:
- To investigate the role of host autolytic enzymes in Dp-1 phage release.
- To elucidate the contribution of a newly discovered phage-associated lysin (PAL) in pneumococcal lysis.
- To understand the interplay between host and phage factors in Dp-1 infection.
Main Methods:
- Experiments using autolysis-defective pneumococcal mutants and wild-type cells.
- Manipulation of infection conditions, including phage-to-cell ratios and incubation temperatures.
- Assessing the effect of purified pneumococcal autolysin on mutant resistance.
- Investigating the impact of reducing agents and cardiolipin on lysis stimulated by phage-associated lysin (PAL).
Main Results:
- Resistance of autolysis-defective mutants to Dp-1 infection at low phage ratios was overcome by pre-coating with wild-type pneumococcal autolysin.
- Productive infection was restored in mutants at 30 degrees C due to partial activation of thermosensitive autolysin.
- Phage-associated lysin (PAL) significantly stimulated lysis, with activity modulated by reducing agents and cardiolipin.
Conclusions:
- Both host autolytic enzymes and phage-associated lysin (PAL) are integral to Dp-1 induced lysis of pneumococci.
- Host autolysin activity plays a significant role in susceptibility to Dp-1 infection.
- Phage-associated lysin (PAL) is a key factor in bacteriophage release and overall culture lysis.