Monitoring fibril formation of the N-terminal domain of PABPN1 carrying an alanine repeat by tryptophan fluorescence and real-time NMR

Rohrberg, Julia; Sachs, Rolf; Lodderstedt, Grit; Sackewitz, Mirko; Balbach, Jochen; Schwarz, Elisabeth

doi:10.1016/j.febslet.2008.04.002

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Volume 582, Issue 11 , Pages 1587-1592, 14 May 2008

Monitoring fibril formation of the N-terminal domain of PABPN1 carrying an alanine repeat by tryptophan fluorescence and real-time NMR

Edited by Jesus Avila

Julia Rohrberg
- Institute for Biochemistry and Biotechnology of the Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Strasse 3, 06120 Halle, Germany
- Present address: Technical University Munich, Institute for Organic Chemistry and Biochemistry, Lichtenbergstrasse 4, 85747 Garching, Germany.
Rolf Sachs
- Institute of Physics, Biophysics Group and “Mitteldeutsches Zentrum für Struktur und Dynamik der Proteine, MZP” of the Martin-Luther-University Halle-Wittenberg, Hoher Weg 8, 06120 Halle, Germany
Grit Lodderstedt
- Institute for Biochemistry and Biotechnology of the Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Strasse 3, 06120 Halle, Germany
- Present address: Scil Proteins GmbH, Heinrich-Damerow-Strasse 1, 06120 Halle, Germany.
Mirko Sackewitz
- Institute for Biochemistry and Biotechnology of the Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Strasse 3, 06120 Halle, Germany
Jochen Balbach
- Institute of Physics, Biophysics Group and “Mitteldeutsches Zentrum für Struktur und Dynamik der Proteine, MZP” of the Martin-Luther-University Halle-Wittenberg, Hoher Weg 8, 06120 Halle, Germany
Elisabeth Schwarz
- Institute for Biochemistry and Biotechnology of the Martin-Luther-University Halle-Wittenberg, Kurt-Mothes-Strasse 3, 06120 Halle, Germany
- Corresponding author. Fax: +49 345 55 27 013.

Received 20 February 2008; received in revised form 2 April 2008; accepted 2 April 2008. published online 10 April 2008.

Abstract

Intranuclear fibrils due to poly-alanine expansions in the N-terminal domain of the poly(A) binding protein PABPN1 correlate with the disease oculopharyngeal muscular dystrophy (OPMD). For monitoring fibril formation by fluorescence and real-time NMR spectroscopy, tryptophans were introduced either into the middle or C-terminal of the poly-alanine segment. The kinetics of fibril formation which were monitored by fluorescence spectroscopy were matched by real-time NMR kinetics. Our results show that fibril formation is concomitant with the burial of the tryptophans in the fibrillar core. Since no soluble pre-fibrillar intermediate(s) was detected, fibril formation of this domain may be regarded as a two state conversion from an unfolded soluble into folded insoluble species.

Keywords: Poly-alanine, PABPN1, Fibril formation, Real-time NMR, Tryptophan fluorescence, Trinucleotide expansion