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DNA mobility in crystals of a nonspecific lambda cro/DNA complex
D E Klimenko1, B K Chernov, L V Malinina
1Engelhardt Institute of Molecular Biology, Russian Academy of Sciences, Moscow.
Journal of Biomolecular Structure & Dynamics
|December 1, 1995
Summary
This study reveals that DNA in nonspecific lambda cro/DNA complexes can occupy two overlapping positions within the crystal structure. This DNA mobility may be a common characteristic of such repressor/DNA complexes.
Area of Science:
- Structural Biology
- Crystallography
- Molecular Biology
Background:
- Nonspecific DNA binding is crucial for gene regulation.
- Understanding the structural basis of DNA-protein interactions is key.
Purpose of the Study:
- To determine the precise location and orientation of DNA within crystals of the lambda cro/(GT)4.(AC)4 complex.
- To investigate potential DNA mobility in repressor-DNA complexes.
Main Methods:
- Isomorphous replacement method using heavy atom derivatives (iodinated and brominated oligonucleotides).
- Analysis of heavy atom positions.
- Integration with existing molecular replacement data.
Main Results:
- The DNA octamer was found to occupy two overlapping positions in the crystal.
- Each DNA duplex forms part of an imaginary longer double helix, shifted by two base pairs.
- Different orientations of the DNA octamer were observed in heavy atom derivative crystals.
Conclusions:
- The DNA octamer exhibits mobility within the crystal lattice.
- This observed DNA mobility is likely a general feature of nonspecific repressor/DNA complexes.