Tubulin must be acetylated in order to form a complex with membrane Na(+),K (+)-ATPase and to inhibit its enzyme activity.
In cells of neural and non-neural origin, tubulin forms a complex with plasma membrane Na(+),K(+)-ATPase, resulting in inhibition of the enzyme activity. When cells are treated with 1 mM L-glutamate, the complex is dissociated and enzyme activity is restored. Now, we found that in CAD cells, ATPase is not activated by L-glutamate and tubulin/ATPase complex is not present in membranes. By investigating the causes for this characteristic, we found that tubulin must be acetylated in order to associate with ATPase and to inhibit its catalytic activity. In CAD cells, the acetylated tubulin isotype is absent. Treatment of CAD cells with deacetylase inhibitors (trichostatin A or tubacin) caused appearance of acetylated tubulin, formation of tubulin/ATPase complex, and reduction of membrane ATPase activity. In these treated cells, addition of 1 mM L-glutamate dissociated the complex and restored the enzyme activity. Cytosolic tubulin from trichostatin A-treated but not from non-treated cells inhibited ATPase activity. These findings indicate that the acetylated isotype of tubulin is required for interaction with membrane Na(+),K(+)-ATPase and consequent inhibition of enzyme activity.
Santander
Verónica S
VS
Centro de Investigaciones en Química Biológica de Córdoba (CIQUIBIC), UNC-CONICET, Departamento de Química Biológica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, 5000, Córdoba, Argentina.
Bisig
C Gastón
CG
Purro
Silvia A
SA
Casale
César H
CH
Arce
Carlos A
CA
Barra
Héctor S
HS
D000107:Acetylation / Q000187:drug effects; D000581:Amidohydrolases / Q000037:antagonists & inhibitors; D000818:Animals; D019556:COS Cells; D002462:Cell Membrane / Q000201:enzymology*; D002522:Chlorocebus aethiops; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018698:Glutamic Acid / Q000494:pharmacology; D006877:Hydroxamic Acids / Q000494:pharmacology; D051379:Mice; D051381:Rats; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D014404:Tubulin / Q000737:chemistry* / Q000378:metabolism*
D004791:Enzyme Inhibitors; D006877:Hydroxamic Acids; D014404:Tubulin; D018698:Glutamic Acid; C012589:trichostatin A; D000581:Amidohydrolases; D000254:Sodium-Potassium-Exchanging ATPase