An intramolecular cross-talk in D29 mycobacteriophage endolysin governs the lytic cycle and phage-host population...

Area of Science:

• Microbiology and Virology
• Bacteriophage Biology
• Molecular Mechanisms of Viral Replication

Background:

• Mycobacteriophage D29 utilizes the LysA endolysin for host cell lysis, targeting the peptidoglycan layer.
• LysA shows potential as a therapeutic agent against mycobacterial infections.
• The precise regulatory mechanisms governing LysA activity during the phage lytic cycle are not fully understood.

Purpose of the Study:

• To elucidate the structural and functional regulation of LysA during the D29 phage lytic cycle.
• To investigate how LysA activity influences phage-host population dynamics and the lytic cycle phases.
• To determine the conformational states of LysA and the triggers for its activation and inactivation.

Main Methods:

• Investigating LysA protein conformations and activity.
• Analyzing LysA's interaction with host peptidoglycan.
• Studying the timing of LysA activation and inactivation relative to phage progeny assembly and host lysis.
• Assessing the impact of LysA regulation on phage propagation in environmental settings.

Main Results:

• LysA exists in two conformations; only one is enzymatically active.
• LysA activation is dependent on a conformational switch triggered by host peptidoglycan.
• D29 phage maintains an inactive LysA pool, enabling complete phage assembly before host lysis.
• LysA activity is reversible post-lysis, preventing targeting of surrounding bacterial populations.

Conclusions:

• Structural and functional regulation of LysA is crucial for orchestrating host cell lysis and maintaining phage-host population dynamics.
• Peptidoglycan-dependent conformational switching allows for controlled lysis, balancing phage reproduction and propagation.
• Reversible inactivation of LysA post-lysis protects bystander bacteria, enhancing phage survival and spread in the environment.