The incorporation of 3-nitrotyrosine into the cooh-termius of alpha-tubule is reversible and not detrimental for dividing cells.

BISIG, C.G.; PURRO, S.A; CONTIN, M.A.; BARRA, H.S. Y ARCE, C.A

Villa Carlos Paz. Cordoba- Argentina

Congreso; Sociedad Argentina de Investigaciones Bioquímicas y Biología Molecular (SAIB); 2001

The alpha-chain of tubulin is biosynthesized with a tyrosine resi- due at its COOH-terminus. Tubulin carboxypeptidase can remove this tyrosine exposing glutamic acid. Tubulin tyrosine ligase reincorporates tyrosine at that position. 3-Nitrotyrosine (NO2-Tyr) is produced during cell signaling via NO. Recently, its incorporation into the alpha-tubulin COOH-terminus in substitution of tyrosine has been postulated as a causing agent in pathological processes (Eiscrich et al., PNAS 1999, 96:6365). In the present work, we found that NO2-Tyr can be incorporated into tubulin in place of tyrosine and that tubulin carboxypeptidase can remove it in vitro and in living cells. In addition, we found that NO2-Tyr can substitute for tyrosine at the COOH-terminus of alpha-tubulin without noticeable detrimental consequence for the cell. We studied the effect of treatment of cells with NO2-Tyr on cell morphology and viability, proliferation rate, association of the carboxypeptidase with microtubules, microtubular network status and in vitro assembly capability. In no case we found differences with control cells. C6 cells subjected to 2-day cycles of nitrotyrosination, de-nitrotyrosination and re-nitrotyrosination showed normal growth (proliferalion rate, morphology and viability). C6 and A549 cells were maintained during 45 days in F12K medium containing 500 uM of NO2-Tyr without noticeable deleterious effects.