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The R gene product of bacteriophage lambda is the murein transglycosylase
Abstract:
The radioactively labeled proteins synthesised in Escherichia coli minicells infected by bacteriophage lambda R and lambda R+ were compared by polyacrylamide gel electrophoresis. lambda R mutants, which have lost the ability to lyse host cells, lack a polypeptide of molecular weight 17.5 KD corresponding to the molecular weight of murein transglycosylase - a bacteriolytic enzyme from lambda lysates which we have described previously. It has been shown by direct comparison using radio-labeled enzyme that transglycosylase comigrates with the R gene product. The enzyme was undetectable in induced cultures of E. coli W3350 su degrees (lambda cI857 Ram 5) and C600 (lambda cI857 acR301), while it was present in a lambda Rz mutant lysate. We conclude that the transglycosylase is the R gene product.
Insights
Bacteriophage lambda R mutants lacking host cell lysis ability also lack murein transglycosylase. This bacteriolytic enzyme comigrates with the R gene product, identifying it as the enzyme responsible for lysis.
Area of Science:
- Molecular Biology
- Virology
- Microbiology
Background:
- Bacteriophage lambda is a virus that infects Escherichia coli.
- Lambda R mutants are defective in host cell lysis.
- Murein transglycosylase is a bacteriolytic enzyme found in lambda lysates.
Purpose of the Study:
- To identify the R gene product of bacteriophage lambda.
- To determine if murein transglycosylase is the R gene product.
Main Methods:
- Radioactive labeling of proteins synthesized in Escherichia coli minicells infected with bacteriophage lambda.
- Polyacrylamide gel electrophoresis for protein separation and comparison.
- Direct comparison of radio-labeled murein transglycosylase with bacteriophage lambda R gene product.
Main Results:
- Lambda R mutants, unable to lyse host cells, lacked a 17.5 kD polypeptide.
- This 17.5 kD polypeptide comigrated with radio-labeled murein transglycosylase.
- Murein transglycosylase was undetectable in specific induced E. coli cultures but present in a lambda Rz mutant lysate.
Conclusions:
- The murein transglycosylase is the R gene product of bacteriophage lambda.
- The R gene product is essential for the bacteriolytic activity of bacteriophage lambda.