Cavities in protein-DNA and protein-RNA interfaces

Area of Science:

• Structural biology
• Biophysics
• Computational biology

Background:

• Protein-DNA and protein-RNA complexes are crucial for cellular processes.
• Understanding interface characteristics, including cavities, is key to deciphering molecular recognition.
• Transient protein-protein interactions offer a comparative model for interface analysis.

Purpose of the Study:

• To analyze and characterize cavities at protein-nucleic acid interfaces.
• To compare cavity properties in protein-DNA and protein-RNA complexes with protein-protein complexes.
• To investigate the structural and chemical factors influencing cavity formation and properties.

Main Methods:

• Computational analysis of existing structural data for protein-DNA and protein-RNA complexes.
• Quantification of cavity number, volume, and shape.
• Calculation of a cavity index to assess surface complementarity.
• Analysis of residue composition and water molecule presence within cavities.

Main Results:

• Protein-nucleic acid interfaces share similarities in cavity characteristics (number, volume) with transient protein-protein heterocomplexes.
• Homodimeric protein-DNA interfaces show significantly larger cavities, especially those involving both subunits and DNA.
• Cavity index indicates similar atomic packing efficiency in protein-protein/DNA/RNA interfaces compared to homodimer interfaces, which are less efficient.
• Beta-sheet residues line protein-DNA interfaces, and DNA minor grooves are often involved in cavities.
• Larger cavities are less spherical, more solvated, and can contain water molecules mediating interactions.

Conclusions:

• Cavities in protein-nucleic acid complexes are a significant feature, comparable to those in transient protein-protein interactions.
• Interface architecture in homodimeric protein-DNA complexes leads to larger void spaces.
• Surface complementarity and residue composition influence cavity formation, with water playing a role in filling these spaces.