Related Experiment Videos
Characteristics of bacteriophage N1 and its attachment to cells of Micrococcus lysodeikticus
Abstract:
Bacteriophage N1 was purified by differential and equilibrium gradient centrifugation and characterized with respect to bouyant density in CsCl, one-step growth properties, host range, and morphology by electron microscopy. In a tris (hydroxymethyl) aminomethane-magnesium buffer (pH 7.15), the irreversible adsorption of N1 to cells of Micrococcus lysodeikticus strain 1 (ML-1) followed first-order reaction kinetics with an adsorption-velocity constant of 1.6 x 10(-9)/min at 32 C. The rate of phage attachment was not significantly altered when adsorption mixtures contained 0.01 m KCN or 1% casein hydrolysate, 0.01 m CaCl(2), and 0.001 m tryptophan. The activation energy for the irreversible adsorption reaction was 8.6 kcal. Treatment of ML-1 cells by any of the following procedures reduced the irreversible phage receptor activity over 90%: (i) mechanical disruption, (ii) lysozyme digestion, (iii) incubation in 1% cetyltrimethylammonium bromide, or (iv) incubation of heated cells (100 C, 15 min) with trypsin, Pronase, or lysozyme. The sensitivity of the phage receptor activity of ML-1 cells to lysozyme suggests that the bacterial cell wall is involved in the receptor site for the virus. Destruction of receptor activity by the other treatments cited above implies that, in addition to the cell wall, other cellular components may participate in the irreversible attachment of N1 phage to cells.
Insights
Bacteriophage N1 irreversibly attaches to Micrococcus lysodeikticus cells. Receptor activity is reduced by treatments affecting the cell wall and other cellular components, suggesting a complex interaction site for phage N1 attachment.
Area of Science:
- Microbiology
- Virology
- Biochemistry
Background:
- Bacteriophages are viruses that infect bacteria.
- Understanding phage-host interactions is crucial for phage therapy and molecular biology.
- The specific mechanisms of phage attachment are not fully elucidated for all phage-host systems.
Purpose of the Study:
- To characterize bacteriophage N1 and its interaction with Micrococcus lysodeikticus (ML-1).
- To investigate the kinetics and factors influencing the irreversible adsorption of phage N1 to ML-1 cells.
- To identify the cellular components involved in phage N1 receptor activity.
Main Methods:
- Purification of bacteriophage N1 using differential and equilibrium gradient centrifugation.
- Characterization of phage N1 properties including buoyant density, growth, host range, and morphology via electron microscopy.
- Kinetic analysis of phage N1 irreversible adsorption to ML-1 cells under various conditions.
- Treatment of ML-1 cells to assess the impact on phage receptor activity.
Main Results:
- Phage N1 adsorption to ML-1 cells followed first-order kinetics with a specific adsorption-velocity constant.
- Adsorption rate was unaffected by KCN, casein hydrolysate, CaCl(2), or tryptophan.
- Activation energy for irreversible adsorption was determined to be 8.6 kcal.
- Treatments like mechanical disruption, lysozyme digestion, cetyltrimethylammonium bromide, and heat-denaturation followed by enzyme treatment significantly reduced receptor activity.
Conclusions:
- The bacterial cell wall is likely involved in the receptor site for bacteriophage N1, suggested by lysozyme sensitivity.
- Other cellular components, beyond the cell wall, may also participate in the irreversible attachment of phage N1.
- These findings contribute to understanding the molecular basis of phage-bacterial interactions.