Role of the acidic tail of high mobility group protein B1 (HMGB1) in protein stability and DNA bending

High mobility group box (HMGB) proteins are abundant nonhistone proteins found in all eukaryotic nuclei and are capable of binding/bending DNA. The human HMGB1 is composed of two binding motifs, known as Boxes A and B, are L-shaped alpha-helix structures, followed by a random-coil acidic tail that c...

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Bibliographic Details
Published in:PloS one 2013-11, Vol.8 (11), p.e79572-e79572
Main Authors: Belgrano, Fabricio S, de Abreu da Silva, Isabel C, Bastos de Oliveira, Francisco M, Fantappié, Marcelo R, Mohana-Borges, Ronaldo
Format: Article
Language:English
Subjects:
Binding
Biochemistry
Chironomus
Chromatin remodeling
Chromosomal proteins
Circular dichroism
Crystal structure
Deoxyribonucleic acid
Dichroism
DNA
DNA - chemistry
DNA - metabolism
DNA binding proteins
Drosophila
E coli
Energy consumption
Energy measurement
Energy transfer
Fluorescence
Fluorescence resonance energy transfer
Fluorescence spectroscopy
Guanidine
Guanidine hydrochloride
High mobility group proteins
High temperature
Histones
HMGB1 protein
HMGB1 Protein - chemistry
HMGB1 Protein - metabolism
Humans
In vivo methods and tests
Insects
Intermediates
Mobility
Nonhistone proteins
Nuclei
Nucleic Acid Conformation
pH effects
Protein binding
Protein Stability
Protein structure
Proteins
Saccharomyces cerevisiae
Spectroscopy
Spectrum analysis
Stability
Thermodynamics
Tryptophan
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Summary:High mobility group box (HMGB) proteins are abundant nonhistone proteins found in all eukaryotic nuclei and are capable of binding/bending DNA. The human HMGB1 is composed of two binding motifs, known as Boxes A and B, are L-shaped alpha-helix structures, followed by a random-coil acidic tail that consists of 30 Asp and Glu residues. This work aimed at evaluating the role of the acidic tail of human HMGB1 in protein stability and DNA interactions. For this purpose, we cloned, expressed and purified HMGB1 and its tailless form, HMGB1ΔC, in E. coli strain. Tryptophan fluorescence spectroscopy and circular dichroism (CD) experiments clearly showed an increase in protein stability promoted by the acidic tail under different conditions, such as the presence of the chemical denaturant guanidine hydrochloride (Gdn.HCl), high temperature and low pH. Folding intermediates found at low pH for both proteins were denatured only in the presence of chemical denaturant, thus showing a relatively high stability. The acidic tail did not alter the DNA-binding properties of the protein, although it enhanced the DNA bending capability from 76° (HMGB1ΔC) to 91° (HMGB1), as measured using the fluorescence resonance energy transfer technique. A model of DNA bending in vivo was proposed, which might help to explain the interaction of HMGB1 with DNA and other proteins, i.e., histones, and the role of that protein in chromatin remodeling.
ISSN:1932-6203
1932-6203
DOI:10.1371/journal.pone.0079572