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Two alternative mechanisms of cell separation in staphylococci: one lytic and one mechanical
P Giesbrecht1, T Kersten, H Maidhof
1Robert Koch-Institut, Nordufer 20, D-13353 Berlin, Germany.
Abstract:
Electron microscopy studies revealed two different mechanisms of cell separation in Staphylococcus aureus. Both mechanisms were initiated by the centrifugal lytic action (directed outward from the center) of murosomes, which perforated the peripheral cell wall. Thereafter, during the first type of cell separation, murosomes also lysed large parts of the cross wall proper in the opposite, i.e., centripetal direction, forming spokelike lytic lesions ("separation scars") next to the most prominent structure of the cross wall, the splitting system. This bidirectional lytic action of murosomes revealed that the staphylococcal cross wall is composed of permanent and transitory parts; transitory parts constituted about one-third of the volume of the total cross wall and seemed to be digested during cell separation. The second mechanism of cell separation was encountered within the splitting system, which has been regarded as the main control unit for lytic cell separation for more than 25 years. The splitting system, however, represents mainly a mechanical aid for cell separation and becomes effective when cell-wall autolytic activities are insufficient.
Insights
Staphylococcus aureus cell separation involves murosomes perforating the cell wall. A second mechanism utilizes the splitting system as a mechanical aid when autolytic activity is low.
Area of Science:
- Microbiology
- Cell Biology
- Biochemistry
Background:
- Bacterial cell division and separation are crucial for growth and proliferation.
- Staphylococcus aureus is a significant human pathogen requiring effective cell separation for colonization.
- The precise mechanisms of cell wall lysis and separation in Staphylococcus aureus remain incompletely understood.
Purpose of the Study:
- To elucidate the distinct mechanisms of cell separation in Staphylococcus aureus.
- To investigate the role of murosomes and the splitting system in bacterial cell division.
- To characterize the composition and dynamics of the staphylococcal cross wall during separation.
Main Methods:
- High-resolution electron microscopy was employed to visualize cell separation processes.
- Detailed analysis of lytic lesions and structural components of the cell wall was performed.
- Comparative analysis of different cell separation events was conducted.
Main Results:
- Two distinct cell separation mechanisms were identified in Staphylococcus aureus.
- Murosomes initiate cell separation via centrifugal lysis of the peripheral cell wall.
- A bidirectional lytic action of murosomes reveals permanent and transitory cross wall components, with transitory parts digested during separation.
Conclusions:
- Staphylococcus aureus employs at least two distinct mechanisms for cell separation.
- Murosomes play a central role in initiating cell wall lysis during separation.
- The splitting system functions primarily as a mechanical support during cell separation, particularly when autolytic activity is insufficient.