INVESTIGADORES
ROMAN Ernesto Andres
congresos y reuniones científicas
Título:
Stability and folding kinetics of frataxin from Psychromonas ingrahamii are highly modulated by pH
Autor/es:
ERNESTO A. ROMAN; RODOLFO M. GONZALEZ LEBRERO; JAVIER SANTOS
Lugar:
Carlos Paz
Reunión:
Congreso; Reunion Anual del la Sociedad Argentina de Biofísica; 2013
Institución organizadora:
Sociedad Argentina de Biofísica
Resumen:
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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
