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Pf1 Inovirus. Electron density distribution calculated by a maximum entropy algorithm from native fibre diffraction
Journal of Molecular Biology
|January 20, 1987
Summary
Researchers determined the electron density of the Pf1 bacteriophage using X-ray fiber diffraction and a maximum entropy method. The structure reveals its protein subunits are curved alpha-helices arranged in an unexpected configuration.
Area of Science:
- Structural biology
- Biophysics
- X-ray crystallography
Background:
- Filamentous bacteriophages are important viral models.
- Understanding their structure provides insights into viral assembly and function.
Purpose of the Study:
- To calculate the electron density distribution of the Pf1 bacteriophage.
- To elucidate the secondary structure and arrangement of its protein subunits.
Main Methods:
- Maximum entropy method applied to X-ray fiber diffraction data.
- Inclusion of native and isomorphous derivative data up to 3 Å resolution.
Main Results:
- The 46-residue protein subunit is a single, curved alpha-helix.
- Alpha-helix subunits decrease in radius from N to C terminus.
- Subunits exhibit an unexpected negative angle relative to their neighbors.
Conclusions:
- The Pf1 bacteriophage protein subunit is a curved alpha-helix.
- The arrangement of these helices is unique and provides a refined structural model.