Functional analysis of a class I holin, P2 Y

Area of Science:

• Bacteriophage biology
• Molecular genetics
• Membrane protein function

Background:

• The Y protein of coliphage P2 is a putative holin, analogous to the lambda phage S105 protein.
• Holins are essential phage proteins that trigger lysis by forming pores in the bacterial membrane.
• Understanding holin function is crucial for deciphering phage-bacterial interactions and programmed cell death.

Purpose of the Study:

• To characterize the functional properties of the P2 phage Y protein as a holin.
• To compare the functional requirements of Y holin with canonical class I holins like lambda S105.
• To identify the antiholin interacting with P2 Y holin.

Main Methods:

• Physiological and genetic approaches were employed.
• Analysis of allele-specific delayed-onset lethality.
• Assessment of membrane energization sensitivity.

Main Results:

• P2 Y protein exhibits essential holin criteria, including programmed lysis timing and membrane energization dependence.
• Y holin function is dependent on the integrity of its C-terminal cytoplasmic domain.
• LysA, a predicted membrane protein, functions as a Y-specific antiholin.

Conclusions:

• Class I holins share conserved features for precise control of phage lysis.
• The P2 Y holin presents unique requirements for its C-terminal domain compared to lambda S105.
• The P2 lysis cassette utilizes LysA as a specific antiholin, distinct from the lambda S107 system.