Structure and synthesis of a lipid-containing bacteriophage. An endolysin activity associated with bacteriophage PM2

Area of Science:

• Microbiology
• Virology
• Enzymology

Background:

• Bacteriophages are viruses that infect bacteria, playing crucial roles in microbial ecosystems and potential therapeutic agents.
• Endolysins are phage-encoded peptidoglycan hydrolases typically released upon phage lysis, though some are associated with the virion.
• Pseudomonas BAL-31 is a bacterial host susceptible to bacteriophage infection.

Purpose of the Study:

• To investigate the presence and localization of endolysin activity within bacteriophage PM2.
• To characterize the enzymatic properties of the endolysin associated with bacteriophage PM2.
• To identify which structural component of bacteriophage PM2 possesses endolysin activity.

Main Methods:

• Induction of endolysin in Pseudomonas BAL-31 infected with bacteriophage PM2.
• Association of endolysin with purified bacteriophage PM2 virions.
• Assay of endolysin activity in the presence of various divalent cations.
• Disruption of purified virions to assess changes in endolysin activity.
• Purification of bacteriophage PM2 structural proteins and subsequent endolysin activity assay.

Main Results:

• Endolysin activity was detected in Pseudomonas BAL-31 infected with bacteriophage PM2 and associated with purified virions.
• The enzyme's activity was dependent on divalent cations, with Ca2+ being the most effective.
• Endolysin activity increased up to threefold upon virion disruption and was localized to the viral nucleocapsid.
• Purified nucleocapsid protein (III) of bacteriophage PM2 exhibited endolysin activity.

Conclusions:

• Bacteriophage PM2 harbors an endolysin enzyme localized within its virion, specifically associated with the nucleocapsid.
• The endolysin requires divalent cations, particularly Ca2+, for optimal activity.
• This finding contributes to understanding bacteriophage structure and the lytic mechanism.