Function and stability: design and characterization of human frataxin variants

NOGUERA, MARTÍN EZEQUIEL; CASTRO, IGNACIO HUGO; SANTOS, JAVIER; BRINGAS, MAURO

Congreso; Primeras Jornadas Virtuales SAB 2020; 2020

Frataxin (FXN) is a mitochondrial protein involved in iron-sulfur cluster biosynthesis, it isan activator of the protein complex (NFS1/ACP-ISD11/ISCU/FXN)2. A deficiency of FXNexpression and/or function results in a neurodegenerative disease, Friedreich's ataxia.This deficient expression is caused by a decrease in the fxn gene transcription or by thepresence of mutations leading to FXN variants with stability and/or functionalimpairment, with more aggregation tendency or with altered internal mobility. Here, weshow results concerning the design and study of a set of human FXN variants. Our goalwas to find FXN variants with increased thermodynamic stability compared to the wildtype protein and decreased degradation tendency in the cell. We used stability predictorsFOLDX and Dynamut to choose seven mutations. The recombinant variants weresuccessfully expressed in E. coli and purified and characterized from the functional andstructural viewpoints. Temperature- and urea-induced unfolding experiments analyzedside by side with cysteine desulfurase activity measurements allow us to select thosevariants that are more stable and functional.