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DnaJ (Hsp40 protein) binding to folded substrate impacts KplE1 prophage excision efficiency
Tania M Puvirajesinghe1, Latifa Elantak, Sabrina Lignon
1Laboratoire de Chimie Bactérienne, CNRS UMR7283, Institut de Microbiologie de la Méditerranée, Aix-Marseille University, 31 Chemin Joseph Aiguier, 13402 Marseille Cedex 20, France.
The Journal of Biological Chemistry
|March 2, 2012
Summary
Bacterial DnaJ protein directly interacts with TorI, a factor essential for KplE1 prophage excision. This interaction stabilizes TorI, enhancing its DNA binding and promoting efficient prophage removal from the host genome.
Area of Science:
- Microbiology
- Molecular Biology
- Genetics
Background:
- Temperate phages transfer genes and alter host properties via lysogeny.
- The KplE1 prophage in Escherichia coli is defective for lysis but competent for recombination.
- Prophage excision from the host genome requires the TorI recombination directionality factor.
Purpose of the Study:
- To investigate the direct interaction between TorI and DnaJ.
- To elucidate the mechanism by which DnaJ promotes KplE1 prophage excision.
Main Methods:
- In vitro cross-linking assays
- Limited proteolysis experiments
- Nuclear Magnetic Resonance (NMR) titration experiments
Main Results:
- Direct association between TorI and DnaJ was demonstrated.
- The TorI-DnaJ interaction transiently protected both proteins from trypsin digestion.
- NMR data revealed DnaJ binds specific alpha-helical regions on TorI, opposite its DNA-binding site.
- DnaJ enhances KplE1 excision by stabilizing TorI conformation for DNA binding, independent of DnaK/GrpE.
Conclusions:
- DnaJ directly interacts with TorI, a key factor in KplE1 prophage excision.
- This interaction stabilizes TorI, improving its DNA binding affinity and promoting efficient prophage removal.
- The mechanism involves conformational stabilization of TorI by DnaJ, facilitating site-specific recombination.
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