Journal of Cell Science 115, e2403-e2403 (2002)
Copyright © 2002 The Company of Biologists Limited
Tubulin glutamylase revealed
Polyglutamylation of tubulin is an essential post-translational
modification that regulates interactions between microtubules and associated
proteins. It is cell cycle regulated and appears to be important for centriole
assembly and flagellar motility; however, the enzyme responsible had never
been identified — until now. Using a novel purification scheme involving
hydroxyapatite chromatography, Stefan Westermann and Klaus Weber have purified
and cloned the tubulin polyglutamylase from the trypanosomatid Crithidia
fasciculata (see p.
5003). The 54 kDa protein, CfNek, localizes to the flagellar basal
body and turns out to be a new member of the NIMA family of kinases —
putative cell cycle regulators. CfNek possesses an unusual kinase domain,
lacking the GxGxxG loop involved in ATP binding, but nevertheless has kinase
activity as well as polyglutamylase activity. It also contains a
pleckstrin-homology domain and a PEST sequence (a motif present in many
proteins targeted for rapid degradation). The authors show that probable CfNek
orthologues are present in both Trypanosoma brucei and Leishmania
major. Given that members of the NIMA family from other organisms are
implicated in centrosome maturation, these might also be tubulin
glutamylases.
Related articles in JCS:
- Identification of CfNek, a novel member of the NIMA family of cell cycle regulators, as a polypeptide copurifying with tubulin polyglutamylation activity in Crithidia
- Stefan Westermann and Klaus Weber
JCS 2002 115: 5003-5012.
[Abstract]
[Full Text]
