C-terminal domain of nonhistone protein HMGB1 as a modulator of HMGB1–DNA structural interactions

E Chikhirzhina,A Polyanichko,V Vorob'Ev,H Wieser,Z Leonenko

doi:10.1155/2010/268452

E Chikhirzhina, A Polyanichko + Show 3 more

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https://doi.org/10.1155/2010/268452

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Abstract

The HMGB1 protein (High Mobility Group protein 1) participates in the formation of functionally significant DNA-protein complexes. HMGB1 protein contains two DNA-binding domains and negatively charged C-terminal region. The latter consists of continuous sequence of dicarboxylic amino acids residues. Structural changes in DNA-protein complexes were studied by circular dichroism spectroscopy (CD) and atomic force microscopy (AFM). Natural HMGB1 and recombinant protein HMGB1(A + B) lacked negatively charged C-terminal region were used. The DNA–HMGB1(A + B) complexes demonstrate an unusually high optical activity in 150 mM NaCl solutions. AFM of the latter complexes shows, that at the low concentration of HMGB1 in the complex the protein is distributed along DNA in a random way. Increase of HMGB1 content leads to cooperative interaction and a redistribution of the bound protein molecules on DNA is observed. Based on the data obtained we conclude that protein–protein interactions play a key role in the formation of highly ordered DNA–HMGB1 complexes. It was shown that C-terminal domain modulate the interactions of DNA with HMGB1 protein. We suggest that the C-terminal domain of HMGB1 also modulates the “packing” of HMGB1 molecules on the DNA.

Highlights

Structural-functional relationships in chromatin have been studied for many years
In our previous studies [3] we have shown that depending on HMGB1 to DNA ratio r one can identify several stages of interaction between HMGB1 and DNA characterized by unique structural reorganization of the complexes
Based on the previous results, we expect that the mode of interaction between HMGB-domains and DNA is affected by the negatively charged C-terminal region of HMGB1

Summary

Introduction

Structural-functional relationships in chromatin have been studied for many years. Among numerous DNA-protein complexes determining chromatin functioning [4] the most intriguing ones in many respects are those between DNA and HMGB-domain proteins. In this study we compared the interaction of two proteins HMGB1 itself and a recombinant protein HMGB1(A + B), containing both DNA-binding HMGB-domains, but lacking the C-terminal charged sequence.

Results

Conclusion