Mutants of Streptococcus pneumoniae that contain a temperature-sensitive autolysin
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Abstract:
Two mutants of Streptococcus pneumoniae deficient in autolysin activity produced a protein that showed immunological identity with the N-acetyl-muramyl-L-alanyl-amidase present in the wild-type strain, when tested with antiserum obtained against this enzyme. The protein was produced by the mutant cultures grown either at 37 degrees C or at 30 degrees C, although only the cell extracts obtained at 30 degrees C showed significant cell wall hydrolysing activity. In contrast to the lysis resistance of these bacteria grown at 37 degrees C, mutant cultures grown at 30 degrees C exhibited significant degrees of autolysis when treated with detergent or cell wall inhibitors. Extracts of the mutant cultures contained a cell wall hydrolysing activity that was rapidly inactivated during incubation at 37 degrees C.
Insights
Two Streptococcus pneumoniae mutants produced an autolysin protein immunologically identical to the wild-type enzyme. This protein exhibited cell wall hydrolyzing activity, though it was unstable at 37°C.
Area of Science:
- Microbiology
- Bacterial Cell Wall Metabolism
- Enzymology
Background:
- Streptococcus pneumoniae autolysins are crucial for cell wall hydrolysis and bacterial growth.
- Understanding autolysin activity is key to deciphering bacterial cell division and lysis mechanisms.
Purpose of the Study:
- To investigate the autolysin production and activity in Streptococcus pneumoniae mutants deficient in autolytic activity.
- To characterize the properties of the protein produced by these mutants.
Main Methods:
- Immunological testing using antiserum against wild-type N-acetyl-muramyl-L-alanyl-amidase.
- Growth of mutant cultures at different temperatures (30°C and 37°C).
- Assay of cell wall hydrolyzing activity in cell extracts.
- Assessment of autolysis upon treatment with detergent or cell wall inhibitors.
Main Results:
- Mutants produced a protein immunologically identical to the wild-type N-acetyl-muramyl-L-alanyl-amidase.
- Cell extracts from mutants grown at 30°C showed significant cell wall hydrolyzing activity, unlike those at 37°C.
- Mutant cultures grown at 30°C exhibited autolysis when treated, contrasting with lysis resistance at 37°C.
- The cell wall hydrolyzing activity in mutant extracts was rapidly inactivated at 37°C.
Conclusions:
- Streptococcus pneumoniae mutants deficient in autolysin activity can still produce an immunologically similar protein.
- The observed autolytic activity and stability of this protein are temperature-dependent, being more active and less stable at 30°C compared to 37°C.
- This suggests a complex regulation of autolysin activity and stability in Streptococcus pneumoniae.