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Role of autolysin in generating the pneumococcal purpura-producing principle
Abstract:
The results of four studies described in this paper support the idea that pneumococcal autolysin (N-acetylmuramyl-L-alanine amidase) plays a key role in generating the pneumococcal purpura-producing principle (PPP) from the bacterial cell wall. This conclusion is based on the observation that (i) concentrates of pneumococcal cell-free extracts prepared at a pH which is inhibitory to autolysin activity contained significantly less PPP activity than extract concentrates prepared at a pH which is optimal for autolysin activity; (ii) PPP activity was not detectable in concentrates of cell-free extracts prepared from cells which contained ethanolamine in the cell wall, but a normal amount of activity was found in extract concentrates derived from cells containing choline in the cell wall; (iii) PPP activity was not detectable in concentrates of cell-free extracts prepared from an autolysin-defective mutant, but a normal amount of activity was found in extract concentrates derived from the wild-type strains; and (iv) incubation of purified wild-type strain cell walls with pneumococcal autolysin resulted in a significant increase in the amount of purpurogenic activity in the supernatant fluids of the incubation mixtures.
Insights
Pneumococcal autolysin is crucial for producing the purpura-producing principle (PPP) from bacterial cell walls. Studies show autolysin activity directly correlates with PPP generation, highlighting its key role.
Area of Science:
- Microbiology
- Biochemistry
Background:
- The pneumococcal purpura-producing principle (PPP) is a factor derived from Streptococcus pneumoniae.
- Understanding the mechanism of PPP generation is important for studying bacterial pathogenesis.
Purpose of the Study:
- To investigate the role of pneumococcal autolysin (N-acetylmuramyl-L-alanine amidase) in the generation of PPP from the bacterial cell wall.
Main Methods:
- Comparing PPP activity in cell-free extracts prepared under varying pH conditions affecting autolysin activity.
- Analyzing PPP activity in extracts from bacteria with different cell wall compositions (ethanolamine vs. choline).
- Assessing PPP activity in extracts from autolysin-defective mutants versus wild-type strains.
- Incubating purified cell walls with pneumococcal autolysin and measuring purpurogenic activity.
Main Results:
- Lower PPP activity was observed in extracts prepared at pH inhibitory to autolysin.
- PPP was undetectable in extracts from cells with ethanolamine in the cell wall, but present with choline.
- Autolysin-defective mutants yielded no detectable PPP activity, unlike wild-type strains.
- Incubation of cell walls with autolysin increased purpurogenic activity in supernatants.
Conclusions:
- Pneumococcal autolysin is essential for generating PPP from the bacterial cell wall.
- Autolysin activity directly influences the production of purpurogenic substances.