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Arc repressor-operator DNA interactions and contribution of Phe10 to binding specificity
Lubomír Dostál1, Rolf Misselwitz, Heinz Welfle
1AG Biopolymerspektroskopie, Max-Delbrück-Centrum für Molekulare Medizin Berlin-Buch, Robert-Rössle-Strasse 10, D-13092 Berlin, Germany.
Biochemistry
|June 9, 2005
Summary
This study reveals how Salmonella bacteriophage P22 Arc repressors bind operator DNA. Variants like Arc-F10H show distinct Trp14 and His10 conformations, impacting DNA binding and protein structure.
Area of Science:
- Molecular Biology
- Biophysics
- Structural Biology
Background:
- Arc repressor is a transcriptional regulator from bacteriophage P22.
- Understanding repressor-DNA interactions is crucial for gene regulation studies.
Purpose of the Study:
- To characterize the solution properties of wild-type and F10H mutant Arc repressors and their DNA complexes.
- To compare these properties with known crystal structures and elucidate binding mechanisms.
Main Methods:
- Circular dichroism spectroscopy
- Fluorescence spectroscopy
- Raman difference spectroscopy
- Comparison with existing crystal structures
Main Results:
- Both Arc-wt and Arc-F10H significantly alter operator DNA Raman spectra upon binding.
- Raman data indicate major groove binding, direct base contacts, and DNA bending.
- Trp14 shows altered rotation in free Arc-F10H but similar angles in DNA complexes.
- His10 in Arc-F10H adopts a hydrophobic core conformation when free and a looped-out conformation when bound to DNA.
Conclusions:
- Arc repressor binding involves major groove interactions and DNA structural changes.
- The F10H mutation influences the conformation of key residues (Trp14, His10) affecting DNA binding.
- Spectroscopic methods provide insights into repressor-DNA complex dynamics and structure.