Ionic switch controls the DNA state in phage λ
- Carnegie Mellon Univ., Pittsburgh, PA (United States). Physics Dept.
- Argonne National Lab., Argonne, IL (United States). Advanced Photon Source, X-ray Science Div.
- George Washington Univ., Washington, DC (United States). Dept. of Physics.
- Carnegie Mellon Univ., Pittsburgh, PA (United States). Physics Dept.; Lund Univ., Lund (Sweden). Dept. of Biochemistry and Structural Biology.
We have recently found that DNA packaged in phage λ undergoes a disordering transition triggered by temperature, which results in increased genome mobility. This solid-to-fluid like DNA transition markedly increases the number of infectious λ particles facilitating infection. However, the structural transition strongly depends on temperature and ionic conditions in the surrounding medium. Using titration microcalorimetry combined with solution X-ray scattering, we mapped both energetic and structural changes associated with transition of the encapsidated λ-DNA. Packaged DNA needs to reach a critical stress level in order for transition to occur. We varied the stress on DNA in the capsid by changing the temperature, packaged DNA length and ionic conditions. We found striking evidence that the intracapsid DNA transition is ‘switched on’ at the ionic conditions mimicking those in vivo and also at the physiologic temperature of infection at 37°C. This ion regulated on-off switch of packaged DNA mobility in turn affects viral replication. The results suggest a remarkable adaptation of phage λ to the environment of its host bacteria in the human gut. The metastable DNA state in the capsid provides a new paradigm for the physical evolution of viruses.
- Research Organization:
- Argonne National Laboratory (ANL), Argonne, IL (United States)
- Sponsoring Organization:
- USDOE
- Grant/Contract Number:
- AC02-06CH11357
- OSTI ID:
- 1221840
- Journal Information:
- Nucleic Acids Research, Journal Name: Nucleic Acids Research Journal Issue: 13 Vol. 43; ISSN 0305-1048
- Publisher:
- Oxford University PressCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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