IQUIFIB   02644
INSTITUTO DE QUIMICA Y FISICOQUIMICA BIOLOGICAS "PROF. ALEJANDRO C. PALADINI"
Unidad Ejecutora - UE
artículos
Título:
The Alteration of the C-terminal Region of Human Frataxin Distorts its Structural Dynamics and Function
Autor/es:
SANTIAGO E. FARAJ; ERNESTO A. ROMAN; MARTÍN ARÁN; MARIANA GALLO; JAVIER SANTOS
Revista:
FEBS JOURNAL
Editorial:
WILEY-BLACKWELL PUBLISHING, INC
Referencias:
Lugar: Londres; Año: 2014 vol. 281 p. 3397 - 3419
ISSN:
1742-464X
Resumen:
Friedreich´s Ataxia (FRDA) is linked to a deficiency of frataxin (FXN), a mitochondrial protein involved in iron-sulfur cluster synthesis. FXN is a small protein with an α/β fold followed by the C-terminal region (CTR) with a non periodic structure that packs against the protein core. Here, we explore the impact of the alteration of the CTR on the stability and dynamics of FXN. We analyzed several pathological and rationally designed CTR mutants using complementary spectroscopic and biophysical approaches. The pathological mutation L198R yields a global destabilization of the structure correlating with a significant and highly localized alteration of dynamics, mainly involving residues that are in contact with L198 in wild-type FXN. Variant FXN90-195--closely related to the FRDA-associated mutant FXN81-193--conserves a globular shape with a native-like structure. However, the truncation of the CTR results in an extreme alteration of global stability and protein dynamics over a vast range of timescales and encompassing regions far from the CTR, as shown by proton-water exchange rates and 15N-relaxation measurements. Increased sensitivity to proteolysis, observed in vitro for both mutants, suggests a faster degradation rate in vivo whereas the enhanced tendency to aggregate exhibited by the truncated variant may account for the loss of functional FXN, both phenomena providing an explanation as to why the alteration of the CTR causes FRDA. These results contribute to understanding how stability and activity are linked to protein motions and they might be useful for the design of target-specific ligands to control local protein motions for stability enhancement.