title: A novel microtubule-depolymerizing kinesin involved in length control of a eukaryotic flagellum.
abstract: Cilia and flagella are complex, microtubule (MT)-filled cell organelles of which the structure is evolutionarily conserved from protistan cells to mammalian sperm and the size is regulated. The best-established model for flagellar length (FL) control is set by the balance of continuous MT assembly and disassembly occurring at the flagellar tip. Because steady-state assembly of tubulin onto the distal end of the flagellum requires intraflagellar transport (IFT)--a bidirectional movement of large protein complexes that occurs within the flagellum--FL control must rely upon the regulation of IFT. This does not preclude that other pathways might "directly" affect MT assembly and disassembly. Now, among the superfamily of kinesins, family-13 (MCAK/KIF2) members exhibit a MT-depolymerizing activity responsible for their essential functions in mitosis. Here we present a novel family-13 kinesin from the flagellated protozoan parasite Leishmania major, that localizes essentially to the flagellum, and whose overexpression produces flagellar shortening and knockdown yields long flagella. Using negative mutants, we demonstrate that this phenotype is linked with the MT-binding and -depolymerizing activity of this kinesin. This is the first report of an effector protein involved in FL control through a direct action in MT dynamics, thus this finding complements the assembly-disassembly model.
authors: Laboratoire de Parasitologie-Mycologie, Biologie Moléculaire, Biologie Cellulaire et Biodiversité des Protozoaires Parasites, FRE 3013 Centre National de Recherche Scientifique/Université Montpellier I, Montpellier, France. genpara@univ-montp1.fr
authors: Christine
authors: C
authors: Blaineau
authors: Magali
authors: M
authors: Tessier
authors: Pascal
authors: P
authors: Dubessay
authors: Lena
authors: L
authors: Tasse
authors: Lucien
authors: L
authors: Crobu
authors: Michel
authors: M
authors: Pagès
authors: Patrick
authors: P
authors: Bastien
mesh_terms: D000818:Animals; D005407:Flagella / Q000378:metabolism* / Q000502:physiology; D016547:Kinesins / Q000235:genetics / Q000378:metabolism*; D018320:Leishmania major / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism; D008954:Models, Biological; D009929:Organ Size / Q000502:physiology; D021381:Protein Transport / Q000502:physiology; D034622:RNA Interference
chemical_list: D016547:Kinesins