Jp. Eiserich et al., Microtubule dysfunction by posttranslational nitrotyrosination of alpha-tubulin: A nitric oxide-dependent mechanism of cellular injury, P NAS US, 96(11), 1999, pp. 6365-6370
Citations number
55
Categorie Soggetti
Multidisciplinary
Journal title
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
NO(2)Tyr (3-Nitrotyrosine) is a modified amino acid that is formed by nitri
c oxide-derived species and has been implicated in the pathology of diverse
human diseases. Nitration of active-site tyrosine residues is known to com
promise protein structure and function, Although free NO(2)Tyr is produced
in abundant concentrations under pathological conditions, its capacity to a
lter protein structure and function at the translational or posttranslation
al level is unknown. Here, we report that free NO(2)Tyr is transported into
mammalian cells and selectively incorporated into the extreme carboxyl ter
minus of cu-tubulin via a posttranslational mechanism catalyzed by the enzy
me tubulin-tyrosine ligase, In contrast to the enzymatically regulated carb
oxyl-terminal tyrosination/detyrosination cycle of alpha-tubulin, incorpora
tion of NO(2)Tyr shows apparent irreversibility, Nitro-tyrosination of alph
a-tubulin induces alterations in cell morphology, changes in microtubule or
ganization, loss of epithelial-barrier function, and intracellular redistri
bution of the motor protein cytoplasmic dynein, These observations imply th
at posttranslational nitrotyrosination of Lu-tubulin invokes conformational
changes, either directly or via allosteric interactions, in the surface ex
posed carboxyl terminus of cu-tubulin that compromises the function of this
critical domain in regulating microtubule organization and binding of moto
r-and microtubule-associated proteins. Collectively, these observations ill
ustrate a mechanism whereby free NO(2)Tyr can impact deleteriously on cell
function under pathological conditions encompassing reactive nitrogen speci
es production. The data also yield further insight into the role that the a
lpha-tubulin tyrosination/detyrosination cycle plays in microtubule functio
n.