Escherichia coli capsule bacteriophages. V. Lysozyme 29

Area of Science:

• Microbiology
• Enzymology
• Bacteriophage Research

Background:

• Escherichia coli bacteriophage 29 infection induces host capsule depolymerase.
• A large bacteriolytic enzyme is also synthesized during infection.

Purpose of the Study:

• To purify and characterize the bacteriolytic enzyme induced by bacteriophage 29.
• To determine if this enzyme is associated with the bacteriophage particle.

Main Methods:

• Enzyme purification to homogeneity.
• Biochemical analysis of murein sacculi degradation products.
• Electron microscopy for particle visualization.
• Sedimentation equilibrium and gel chromatography for molecular weight estimation.
• Sodium dodecyl sulfate-polyacrylamide gel electrophoresis for subunit analysis.

Main Results:

• The enzyme was identified as a lysozyme (mucopeptide N-acetylmuramylhydrolase).
• Purified lysozyme is a large particle (approx. 270,000 Da) composed of ~46,000 Da subunits.
• Less than 1% of lytic activity was associated with phage particles, and no 46,000 Da polypeptide was detected in virions.

Conclusions:

• Lysozyme 29 is a distinct, large enzyme induced by phage 29 infection.
• Despite its size, lysozyme 29 is not an integral component of the bacteriophage 29 particle.