INVESTIGADORES
GONZALEZ LEBRERO Rodolfo Martin
congresos y reuniones científicas
Título:
Stability and folding kinetics of frataxin from Psychromonas ingrahamii are highly modulated by pH
Autor/es:
EA. ROMAN; RM. GONZÁLEZ LEBRERO; J. SANTOS
Lugar:
Villa Carlos Paz
Reunión:
Congreso; XLII reunión anual de la Sociedad Argentina de Biofísica; 2013
Institución organizadora:
Sociedad Argentina de Biofísica
Resumen:
Frataxin is a highly conserved protein among biology kingdoms. In humans its absence yields Friedreich´s ataxia. In our laboratory we study iron binding and its effect on stability and dynamics of different frataxin variants. In this work, we explored folding kinetics of frataxin from Psychromonas ingrahamii (pFXN) at different pHs. Previous results from our laboratory revealed that pFXN stability is highly modulated by pH in the 6 to 8 range1. Molecular dynamics simulations also suggested that histidine residues could be participating in this effect. Here we introduce stopped-flow experiments studying pFXN folding and unfolding reaction by monitoring Trp-fluorescence and circular dichroism at different pHs. Results show that both signals reproduce well our previous equilibrium measurements by means of equilibrium constant and total signal change. Moreover, observed rate constants obtained by both kinetic measurements yield similar results. Our experiments indicate that as the pH becomes more acid, the rate constant of folding becomes higher and unfolding rate constant lower. Future experiments with histidine point mutations would shed light in the role of these residues and pH in general in the folding reaction. Acknowledgements. We thank Diego Ferreiro and Ignacio Sanchez for fruitful discussions. References Roman, E., A. Biochimica et Biophysica Acta. 2013 (1834):1168-80.