Natural variants of human apolipoprotein A-I: structural perturbations associated with protein misfolding

CORTEZ, M. FERNANDA; RAMELLA, N. A; FINARELLI, GABRIELA S.; ROSU, S. A; GADDI, G; GISONNO, ROMINA; TRICERRI, M. A.

Ciudad de México

Encuentro; VI Latin American Protein Society Meeting and VII Congreso de la Rama de Fisicoquímica, Estructura y Diseño de Proteínas; 2019

Latin American Protein Society

Since the early description of different human apolipoprotein A-I variants associated to amyloidosis, the reason that determines its deposition inducing organ failure has been under research. To shed light into the events associated to protein aggregation, we studied the effect of the structural perturbations induced by the replacement of a Leucine in position 60 by an Arginine as it occurs in the natural amyloidogenic variant (L60R). Circular dichroism, intrinsic fluorescence measurements and proteolysis analysis indicate that L60R is more unstable, more sensitive to cleavage and the N terminus more disorganized than the protein with the native sequence (Wt). A higher tendency to aggregate is also detected when incubated L60R at physiological pH. In addition, the small structural rearrangement observed leads to the release of tumor necrosis factor a and interleukin-1b from a model of macrophages. In spite of that, the conformational stability of the dimer and the binding to lipids is preserved. Our results strongly suggest that the chronic disease may be a consequence of the loss in the native conformation which elicits the release of protein conformations that could be either cytotoxic or precursors of amyloid conformations