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Updated: Jun 26, 2026
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Analyzing and Building Nucleic Acid Structures with 3DNA
Published on: April 26, 2013
A strained DNA binding helix is conserved for site recognition, folding nucleation, and conformational modulation
Diana E Wetzler1, Mariana Gallo, Riccardo Melis
1Fundación Instituto Leloir and IIBBA-CONICET, Patricias Argentinas 435 (C1405BWE), Buenos Aires, Argentina.
Biopolymers
|January 22, 2009
Summary
The HPV16 E2 DNA binding helix adopts a noncanonical alpha-helix structure, differing from typical alpha-helices. This unique conformation is crucial for precise DNA binding and discrimination.
Area of Science:
- Biochemistry
- Structural Biology
- Molecular Biophysics
Background:
- Nucleic acid recognition frequently involves alpha-helices or disordered regions.
- The DNA binding helix of Human Papillomavirus type 16 E2 (HPV16 E2) is a key protein domain for DNA interaction.
Purpose of the Study:
- To investigate the secondary structure and conformational dynamics of the HPV16 E2 DNA binding helix peptide.
- To understand the structural basis for HPV16 E2's DNA binding specificity and affinity.
Main Methods:
- Circular Dichroism (CD) spectroscopy to assess structural changes with pH, temperature, and solvent.
- Nuclear Magnetic Resonance (NMR) experiments to determine peptide structure and dynamics.
- Analysis of existing crystal structure data and NMR chemical shift indexes.
Main Results:
- The peptide exhibited a Type II Polyproline (PII) structure, with an alpha-helix at the N-terminus and PII at the C-terminus.
- Structural analysis revealed a canonical alpha-helix at the N-terminus and a strained 3(10) helix at the C-terminus.
- The peptide displayed significantly reduced DNA binding affinity (10^4-fold lower) and discrimination capacity (500-fold lower) compared to the full domain.
Conclusions:
- The DNA binding helix of HPV16 E2 adopts a noncanonical, strained alpha-helix conformation.
- This unique structure, stabilized by local folding nuclei, is essential for high-affinity and specific DNA binding.
- The findings highlight the importance of specific protein architecture in modulating DNA recognition.
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