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Nonsequence-specific arginine interactions in the nucleosome core particle
Maria García-Pérez1, Marta Pinto, Juan A Subirana
1Departament d'Enginyeria Química, E. T. S. Enginyeria Industrial de Barcelona, Universitat Politécnica de Catalunya, Av. Diagonal 647, E08028 Barcelona, Spain.
Biopolymers
|July 25, 2003
Summary
Basic amino acid side chains, like arginine, interact directionally with DNA in nucleosomes. Phosphate groups exhibit non-directional interactions, influencing protein conformation and charge density effects on DNA binding.
Area of Science:
- Structural Biology
- Biochemistry
- Molecular Biophysics
Background:
- Nucleosomes are fundamental units of DNA packaging in eukaryotes.
- Interactions between DNA and histone proteins are critical for genome regulation.
Purpose of the Study:
- To analyze the orientation of basic amino acid side chains relative to DNA within the nucleosome core particle.
- To understand the directional nature of interactions between arginine residues, DNA phosphates, and histone fragments.
Main Methods:
- Analysis of atomic-level structural data from nucleosome core particles.
- Computational examination of electric fields and intermolecular contacts.
Main Results:
- Arginine side chains show no preferred orientation relative to the DNA electric field.
- Phosphate oxygens bonded to arginine are consistently oriented relative to the guanidinium group, indicating directional arginine interactions.
- A histone H2B fragment displays variable conformations, correlating with increased protein positive charge density.
Conclusions:
- Arginine-DNA interactions are strongly directional, while phosphate-arginine interactions are not.
- High positive charge density in proteins leads to non-specific conformations when interacting with DNA.