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A(2) expression and assembly regulates lysis in Qβ infections
Catrina A Reed1, Carrie Langlais1, Ing-Nang Wang1
1Department of Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843-2128, USA.
Microbiology (Reading, England)
|January 19, 2013
Summary
Phage maturation protein A(2) inhibits bacterial murein synthesis protein MurA to cause cell lysis. Lysis timing depends on the balance between assembled and unassembled A(2) levels, challenging previous models.
Area of Science:
- Bacteriology
- Virology
- Molecular Biology
Background:
- Bacteriophage Qβ maturation protein A(2) is essential for viral infection and lysis.
- A(2) inhibits MurA, a key enzyme in bacterial cell wall biosynthesis, to induce lysis.
- Previous models suggested A(2) requires assembly into virions for MurA inhibition, controlling lysis timing.
Purpose of the Study:
- To investigate the mechanism and timing of lysis induced by bacteriophage Qβ maturation protein A(2).
- To re-evaluate the role of A(2) assembly in MurA inhibition and lysis timing.
- To understand the regulatory balance between assembled and unassembled A(2) and its impact on infection.
Main Methods:
- Investigated MurA inactivation of purified Qβ particles.
- Quantified A(2) protein levels during induced expression from a plasmid.
- Analyzed Qβ por mutants with altered A(2) translation and characterized their infection dynamics.
Main Results:
- MurA was found to inactivate purified Qβ particles, contradicting the requirement for A(2) assembly prior to inhibition.
- Lysis was observed to occur when A(2) levels are equimolar to cellular MurA.
- Qβ por mutants exhibited increased A(2) translation, leading to attenuated infections and reduced burst sizes.
Conclusions:
- The timing of lysis is regulated by the concentration of both assembled and unassembled A(2) protein, not solely by its assembly into virions.
- A delicate balance of A(2) levels is crucial for optimal phage infection cycle and progeny yield.
- Findings challenge existing models of phage-induced lysis timing and highlight the complex regulation of A(2) activity.
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