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Biochemical characterization of a murein hydrolase induced by bacteriophage Dp-1 in Streptococcus pneumoniae:
Abstract:
A phage-associated lysin recently isolated and purified from Streptococcus pneumoniae infected with bacteriophage Dp-1 has been biochemically characterized as an endo-N-acetyl-muramyl-L-alanine amidase. The purified peptides obtained after treatment of the cell wall with phage-associated lysin are composed of glutamic acid, alanine, lysine, glycine, serine, and aspartic acid in the molar ratios of 1.0:1.6:1.0:1.0:0.8:0.6. The N-terminal amino acid of this peptide has been characterized as alanine. This amidase and the inactive form of the amidase (E form) previously purified (J.V. Höltje and A. Tomasz, J. Biol. Chem. 251:4199-4207, 1976) from S. pneumoniae differ in their molecular weights, as well as in their capacity to be stimulated by reducing agents, and do not cross-react immunologically, although anti-phage-associated lysin serum was able to recognize and inhibit both phage-associated lysin and the active form (C form) of the host amidase.
Insights
A novel phage-associated lysin from Streptococcus pneumoniae was identified as an endo-N-acetyl-muramyl-L-alanine amidase. This enzyme differs from the host amidase in molecular weight and immunological properties.
Area of Science:
- Microbiology
- Biochemistry
- Enzymology
Background:
- Bacteriophage lysins are enzymes that degrade bacterial cell walls.
- Streptococcus pneumoniae is a significant human pathogen.
- Bacteriophage Dp-1 infects Streptococcus pneumoniae.
Purpose of the Study:
- To biochemically characterize a phage-associated lysin isolated from Streptococcus pneumoniae infected with bacteriophage Dp-1.
- To compare the properties of this phage-associated lysin with the host amidase.
Main Methods:
- Isolation and purification of phage-associated lysin from Streptococcus pneumoniae.
- Biochemical characterization of the lysin, including peptide composition analysis.
- Comparison of molecular weights, reducing agent stimulation, and immunological cross-reactivity with host amidase.
Main Results:
- The phage-associated lysin was identified as an endo-N-acetyl-muramyl-L-alanine amidase.
- Peptide analysis revealed specific molar ratios of glutamic acid, alanine, lysine, glycine, serine, and aspartic acid.
- The N-terminal amino acid was identified as alanine.
- The phage-associated lysin and the host amidase (E form) exhibited different molecular weights and did not cross-react immunologically.
Conclusions:
- The characterized phage-associated lysin is a distinct enzyme from the host amidase.
- Anti-phage-associated lysin serum recognized and inhibited both the phage-associated lysin and the active form (C form) of the host amidase.
- These findings contribute to understanding phage-host interactions and bacterial cell wall metabolism.