Proteinase sensitivity of bacteriophage lambda tail proteins gpJ and pH in complexes with the lambda receptor

Area of Science:

• Molecular Biology
• Virology
• Biophysics

Background:

• Bacteriophage lambda binding to liposomes involves distinct stages.
• DNA injection occurs from a late-stage complex (type 2).

Purpose of the Study:

• Investigate conformational changes in bacteriophage lambda proteins during DNA injection.
• Elucidate the role of specific proteins in membrane interaction and DNA translocation.

Main Methods:

• Proteolytic degradation assays to assess protein structure.
• Liposome-based binding assays with bacteriophage lambda.
• Analysis of protein-membrane interactions.

Main Results:

• The tail fiber protein (gpJ) becomes more susceptible to degradation in type 2 complexes, suggesting conformational changes and no internal passage.
• The pH protein is protected from proteolysis only when type 2 complexes form with liposomes, indicating membrane association.

Conclusions:

• gpJ undergoes conformational changes, not internal translocation, during DNA injection.
• pH protein association with the membrane is crucial for forming a transmembrane pore for DNA entry.