BACTERIOPHAGE-MU - A TRANSPOSING PHAGE THAT INTEGRATES LIKE RETROVIRUSES

Bacteriophage Mu uses a specialized type of genetic recombination called transposition to both integrate its DNA into that of the host and to amplify its DNA during lytic growth. Studies with Mu have defined the basic mechanisms of the DNA cleavage and joining reactions needed for transposition. These mechanisms appear to be used by many transposable elements that populate prokaryotic and eukaryotic hosts. Mu transposition is also very similar to retroviral integration. This conservation in the reaction mechanism is reflected in the transposition proteins. Mu transposase carries an acidic amino acid motif which is required for catalysis that is found in many other transposases and the retroviral integrases. Regulation of Mu transposition by the controlled assembly of the active transposase tetramer and by interactions between the transposase and MuB protein are also discussed.