Distinct localization and cell cycle dependence of COOH terminally tyrosinolated alpha-tubulin in the microtubules of Trypanosoma brucei brucei.

Abstract

Abstract. 0t-Tubulin can be posttranslationally modified in that its COOH-terminal amino acid residue, tyrosine, can be selectively removed and replaced again. This reaction cycle involves two enzymes, tubulin carboxypeptidase and tubulin tyrosine ligase. The functional significance of this unusual modification is unclear. The present study demonstrates that posttranslational tyrosinolation of tl-tubulin does occur in the parasitic hemoflagellate Trypanosoma brucei brucei and that posttranslational tyrosinolation can be detected in both a-tubulin isoforms found in this organism. Trypanosomes contain a number of microtubular structures: the flagellar axoneme; the subpellicular layer of singlet microtubules which are closely associated with the cell membrane; the basal bodies; and a cytoplasmic pool of soluble tubulin. Tyrosinolated a-tubulin is present in all these populations. However, immunofluorescence studies demonstrate a distinct localization of tyrosinolated a-tubulin within individual microtubules and organelles. This localization is subject to a temporal modulation that correlates strongly with progress of a cell through the cell cycle. Our results indicate that the presence of tyrosinolated ~t-tubulin is a marker for newly formed microtubules.

Disruption of the golgi apparatus with brefeldin a does not destabilize the associated detyrosinated microtubule network

“…Studies have shown that in most cells detyrosinated u-tubulin is enriched in a distinct subset of MTs [Gundersen et al, 1984;Gundersen and Bulinski, 1986a;Chambray-Deakin et al, 1987a,b;Sherwin et al, 1987;Bulinski et al, 19881, which are often associated with MT structures in differentiated cells [Gundersen and Bulinski, 1986b;Sherwin et al, 1987;Wehland and Weber, 1987;Gundersen et al, 1989;Prescott et al, 1989;Baas and Black, 19901. Detyrosinated MTs appear to be more stable to drugs that disrupt MTs [Bre et al, 1987;Khawaja et al, 19881 and to cold temperature [Charnbray-Deakin et al, 1987al.…”

Identification of casein kinase 1, casein kinase 2, and cAMP-dependent protein kinase-like activities in Trypanosoma evansi

“…A number of posttranslational modifications of tubulin have been reported, which include acetylation, tyrosination, phosphorylation, polyglutamilation, and polyglycylation, and these posttranslationally modified tubulin appeared to be associated with specific populations of microtubules (Scherwin et al 1987, Gallo et al 1988. Two new members of the tubulin superfamily, γ and δ, have been described in T. brucei using a genetic approach (Gull 2001).…”

Mitochondrial Development during Life Cycle Differentiation of African Trypanosomes: Evidence for a Kinetoplast-dependent Differentiation Control Point

“…This is particularly informative because basal body position closely shadows kinetoplast migration during differentiation, with the basal bodies moving slightly (ϳ1 m) anterior to the kinetoplast during differentiation of wild-type cells (Matthews et al, 1995). Also YL1/2 provides an obvious early indication of cell cycle reentry because the newly growing flagellum of the daughter cell contains tyrosinated tubulin and is brightly labeled, whereas the old flagellum, being detyrosinated, is unlabeled (Sherwin et al, 1987). Thus, YL1/2 staining provides an assay of later differentiation events by providing a simultaneous indication of morphological restructuring and cell cycle reentry.…”