Presence of pKa Perturbations Among Homeodomain Residues Facilitates DNA Binding

TL;DR

This paper investigates how pKa perturbations in homeodomain proteins' basic residues enhance DNA binding by maintaining positive charges, highlighting electrostatic contributions to protein-DNA interactions.

Contribution

It reveals the conserved presence of upward shifted pKa values in lysine and arginine residues, elucidating their role in facilitating DNA binding.

Findings

Upward shifted pKa values are conserved in homeodomain residues.

pKa perturbations help maintain positive charge for DNA binding.

Electrostatic interactions are critical for homeodomain-DNA affinity.

Abstract

Homeodomain containing proteins are a broad class of DNA binding proteins that are believed to primarily function as transcription factors. Electrostatics interactions have been demonstrated to be critical for the binding of the homeodomain to DNA. An examination of the electrostatic state of homeodomain residues involved in DNA phosphate binding has demonstrated the conserved presence of upward shifted pKa values among the basic residue of lysine and arginine. It is believed that these pKa perturbations work to facilitate binding to DNA since they ensure that the basic residues always retain a positive charge.