Post-traslational incorporation of L-Phenylalanine into the COOH-terminus of alfa-tubulin in living cells

DITAMO Y, DENTESANO Y, ARCE C, BISIG CG

Mar del Plata

Congreso; XXX Congreso anual de la Sociedad Argentina de Neurosciencias; 2015

SAN

The tyrosination/detyrosination cycle occurring at the C-terminus of α-tubulin is one of the most studied post-translational modifications of proteins. Previous in vitro studies showed that L-phenylalanine (Phe) can be incorporated into tubulin in place of tyrosine. Here, we demonstrate that Phe can be incorporated into the COOH-terminus of tubulin in a reversible fashion in cultured cells and that this incorporation is not due to ?de novo? biosynthesis. Phenylalaninated tubulin is able to form microtubules. Phe incorporation occurs in different cell types and it does not interfere with cell viability. We are interested in the incorporation of this amino acid because in patients suffering phenylketonuria, the level of Phe in blood is increased 20-40-fold and the molecular events that lead to the abnormal functioning of the patient brain are not known. Elongation and retraction of neurites in cells of nervous origin (CAD cells) are altered by treatment with high Phe concentration. The rate of elongation and serum induced retraction of neurites seems to be diminished in the presence of Phe suggesting that the dynamics of microtubules and/or the actomyosin system responsible of retraction is involved in the effects induced by Phe treatment. These results allow us to speculate with the hypothesis that the incorporation of Phe into the C-terminus of α-tubulin is responsible or, at least, contributes to the development of the clinical signs of phenylketonuria.