Conformational stability of the RNP domain controls fibril formation of PABPN1

Jens Liebold; Reno Winter; Ralph Golbik; Gerd Hause; Christoph Parthier; Elisabeth Schwarz

doi:10.1002/pro.2769

Conformational stability of the RNP domain controls fibril formation of PABPN1

Protein Sci. 2015 Nov;24(11):1789-99. doi: 10.1002/pro.2769. Epub 2015 Aug 27.

Authors

Jens Liebold¹, Reno Winter¹, Ralph Golbik², Gerd Hause³, Christoph Parthier⁴, Elisabeth Schwarz¹

Affiliations

¹ Department of Protein Biochemistry, Institute of Biochemistry and Biotechnology, Martin Luther University, Halle Wittenberg, 06120, Halle, Germany.
² Department of Virology, Institute of Biochemistry and Biotechnology, Martin Luther University, Halle Wittenberg, 06120, Halle, Germany.
³ Biocenter, Martin Luther University, Halle Wittenberg, 06120, Halle, Germany.
⁴ Department of Physical Biotechnology, Institute of Biochemistry and Biotechnology, Martin Luther University, Halle Wittenberg, 06120, Halle, Germany.

Abstract

The disease oculopharyngeal muscular dystrophy is caused by alanine codon trinucleotide expansions in the N-terminal segment of the nuclear poly(A) binding protein PABPN1. As histochemical features of the disease, intranuclear inclusions of PABPN1 have been reported. Whereas the purified N-terminal domain of PABPN1 forms fibrils in an alanine-dependent way, fibril formation of the full-length protein occurs also in the absence of alanines. Here, we addressed the question whether the stability of the RNP domain or domain swapping within the RNP domain may add to fibril formation. A variant of full-length PABPN1 with a stabilizing disulfide bond at position 185/201 in the RNP domain fibrillized in a redox-sensitive manner suggesting that the integrity of the RNP domain may contribute to fibril formation. Thermodynamic analysis of the isolated wild-type and the disulfide-linked RNP domain showed two state unfolding/refolding characteristics without detectable intermediates. Quantification of the thermodynamic stability of the mutant RNP domain pointed to an inverse correlation between fibril formation of full-length PABPN1 and the stability of the RNP domain.

Keywords: PABPN1; conformational stability; domain swapping; fibril formation; protein misfolding; thermodynamics.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Amyloid / chemistry*
Amyloid / metabolism*
Disulfides / chemistry
Disulfides / metabolism
Humans
Kinetics
Poly(A)-Binding Protein I / chemistry*
Poly(A)-Binding Protein I / metabolism*
Protein Conformation
Protein Structure, Tertiary
Temperature

Substances

Amyloid
Disulfides
PABPN1 protein, human
Poly(A)-Binding Protein I

Associated data

PDB/3B4D