%0 Journal Article
%T Role of delta-tubulin and the C-tubule in assembly of Paramecium basal bodies
%A Nicole Garreau de Loubresse
%A Fran£żoise Ruiz
%A Janine Beisson
%A Catherine Klotz
%J BMC Cell Biology
%D 2001
%I BioMed Central
%R 10.1186/1471-2121-2-4
%X Using the method of gene-specific silencing, we have inactivated the Paramecium delta-tubulin gene, which was recently identified. This inactivation leads to loss of the C-tubule in all basal bodies, without any effect on ciliogenesis. This deficiency does not directly affect basal body duplication, but perturbs the cortical cytoskeleton, progressively leading to mislocalization and loss of basal bodies and to altered cell size and shape. Furthermore, additional loss of B- and even A-tubules at one or more triplet sites are observed: around these incomplete cylinders, the remaining doublets are nevertheless positioned according to the native ninefold symmetry.The fact that in two distinct phyla, delta-tubulin plays a similar role provides a new basis for interpreting phylogenetic relationships among delta-tubulins. The role of delta-tubulin in C-tubule assembly reveals that tubulins contribute subtle specificities at microtubule nucleation sites. Our observations also demonstrate the existence of a prepattern for the ninefold symmetry of the organelle which is maintained even if less than 9 triplets develop.In addition to the alpha-, beta- and gamma-tubulins, essential for microtubule assembly in all eukaryotes, several new tubulin subfamilies have been recently identified in a cascade of discoveries [1]. Complementation cloning of the UNI3 mutation in Chlamydomonas led to the characterization of delta-tubulin, an unexpected fourth member of the tubulin subfamily, involved in assembly of basal bodies [2]. Genome search for delta-tubulin led to identify not only deltas in mammals and protozoa, but also to disclose further new divergent tubulins, epsilon and zeta [3,4,5]. A sixth subfamily, eta, was characterized in Paramecium [6] by complementation cloning of the sm19 mutation affecting basal body duplication [7]. In contrast to alpha-, beta- and gamma-tubulins, the new tubulins, of which a few sequences only are available, do not seem to be present in all eukaryotes
%U http://www.biomedcentral.com/1471-2121/2/4