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Disassembly of the bacteriophage Mu transposase for the initiation of Mu DNA replication

H Nakai1, R Kruklitis

  • 1Department of Biochemistry and Molecular Biology, Georgetown University Medical Center, Washington, D.C. 20007, USA.

The Journal of Biological Chemistry
|August 18, 1995
PubMed

Insights

Host factors are crucial for disassembling the Mu transposase (MuA) complex and initiating Mu DNA replication. These factors enable the formation of a Mu replication fork by removing MuA from the strand transfer complex.

Area of Science:

  • Molecular Biology
  • Genetics
  • Virology

Background:

  • The Mu transposase (MuA) enzyme binds the strand transfer complex (STC) after catalyzing DNA strand transfer, hindering host replication machinery.
  • Host factors are necessary to resolve the MuA-STC complex and initiate DNA replication.

Purpose of the Study:

  • To investigate the roles of host factors in disassembling the MuA-STC complex and initiating Mu DNA synthesis.
  • To elucidate the mechanism by which MuA's interaction with the STC regulates replication initiation.

Main Methods:

  • Biochemical assays to analyze the interaction between MuA, STC, and host factors.
  • Use of proteolysis and mutant proteins (MuA211) to probe the functional requirements for DNA synthesis initiation.

Main Results:

  • Two host factor fractions, Mu Replication Factor alpha (MRF alpha) and MRF beta, were identified.
  • MRF alpha modifies the STC, leading to MuA removal, while MRF beta promotes Mu DNA synthesis initiation.
  • STC integrity is essential; proteolysis or the MuA211 mutation prevents MuA removal and blocks DNA synthesis.

Conclusions:

  • MuA's stable binding to the STC is a critical regulatory step in initiating Mu replication.
  • Host factors MRF alpha and MRF beta orchestrate the disassembly of the MuA-STC complex and the subsequent establishment of a Mu replication fork.

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