Study of frataxin interaction with other proteins and metal ions by capillary electrophoresis

COLLAZO, D; HERRERA, GEORGINA; SANTOS, J; VIZIOLI, NM

Santiago de Chile

Simposio; 22nd Latin-American Symposium on Biotechnology, Biomedical, Biopharmaceutical, and Industrial Applications of Capillary Electrophoresis and Microchip Technology; 2016

Human frataxin (FXN) has a vital role in the biosynthesis of iron-sulfur clusters (Fe-S), inmitochondria and its deficiency leads to a progressive neuromuscular degenerative diseaseknown as Friedreich´s ataxia. FXN is a member of the Fe-S biosynthetic complex, since itphysically and functionally interacts with other proteins of that complex.As an efficient and versatile technique for biomolecule analysis, capillary electrophoresis(CE) can help to elucidate protein-protein and metal-protein interactions. In this work, theinteraction of FXN with iron and cobalt ions, and other proteins, such as ISCU and ISD11was studied by CE under several conditions. Experiments were conducted using bare- andneutral coated-fused silica capillaries. Different background electrolyte composition (HEPES,TRIS, phosphate, and citrate solutions), pH, and additives were tested. CE analyses performedwith 20 mmol/L TRIS solution at pH 7.4 as background electrolyte demonstrated that anincrease of Fe (III) concentration in the FXN sample produced a decrease of free FXNfraction. Additionally, results from titration and nuclear magnetic resonance (NMR) indicatedthat FXN fixes iron and cobalt. The interaction of FXN with other proteins has been inferredfrom changes observed in the protein electrophoretic profile.As might be expected, the use of CE to characterize protein interaction with other proteinsand metal ions in the context of the FXN characterization studies was of great value.