MuB protein allosterically activates strand transfer by the transposase of phage Mu

Area of Science:

• Molecular Biology
• Virology
• Genetics

Background:

• Bacteriophage Mu is a well-studied model for DNA transposition.
• The MuA (transposase) and MuB proteins are essential for Mu genome integration.
• Understanding the interaction between MuA and MuB is key to elucidating transposition mechanisms.

Purpose of the Study:

• To investigate the role of the MuB protein in stimulating MuA-mediated DNA transposition.
• To determine the specific requirements for MuA-MuB interaction and its effect on strand transfer.
• To analyze the impact of MuB's DNA-binding status on target site selection during transposition.

Main Methods:

• Biochemical assays to study protein-protein interactions between MuA and MuB.
• In vitro transposition assays to measure strand transfer efficiency.
• Analysis of DNA target site utilization under varying conditions of MuA and MuB concentrations and MuB modification.

Main Results:

• MuB protein directly interacts with the C-terminal domain of MuA transposase, activating strand transfer.
• MuB stimulates transposition even when not bound to DNA, indicating activation is independent of target DNA binding.
• Under conditions where MuB cannot bind DNA, transposition exclusively utilizes intramolecular target sites due to proximity.

Conclusions:

• The MuA-MuB interaction is crucial for efficient phage Mu DNA transposition.
• MuB's ability to activate MuA is separable from its DNA-binding function.
• Proximity-driven target site selection, particularly intramolecular sites, is favored when MuB's DNA-binding is impaired.