CLASP promotes microtubule rescue by recruiting tubulin dimers to the microtubule.
Spatial regulation of microtubule (MT) dynamics contributes to cell polarity and cell division. MT rescue, in which a MT stops shrinking and reinitiates growth, is the least understood aspect of MT dynamics. Cytoplasmic Linker Associated Proteins (CLASPs) are a conserved class of MT-associated proteins that contribute to MT stabilization and rescue in vivo. We show here that the Schizosaccharomyces pombe CLASP, Cls1p, is a homodimer that binds an alphabeta-tubulin heterodimer through conserved TOG-like domains. In vitro, CLASP increases MT rescue frequency, decreases MT catastrophe frequency, and moderately decreases MT disassembly rate. CLASP binds stably to the MT lattice, recruits tubulin, and locally promotes rescues. Mutations in the CLASP TOG domains demonstrate that tubulin binding is critical for its rescue activity. We propose a mechanism for rescue in which CLASP-tubulin dimer complexes bind along the MT lattice and reverse MT depolymerization with their bound tubulin dimer.
Al-Bassam
Jawdat
J
Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, MA 02115, USA. jawdat@crystal.harvard.edu
Kim
Hwajin
H
Brouhard
Gary
G
van Oijen
Antoine
A
Harrison
Stephen C
SC
Chang
Fred
F
D006801:Humans; D008870:Microtubules / Q000737:chemistry / Q000378:metabolism*; D008958:Models, Molecular; D009687:Nuclear Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D055503:Protein Multimerization; D020836:Protein Structure, Quaternary; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D012568:Schizosaccharomyces / Q000166:cytology / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014404:Tubulin / Q000737:chemistry* / Q000378:metabolism*
D009687:Nuclear Proteins; C513960:Peg1 protein, S pombe; D011993:Recombinant Fusion Proteins; D029702:Schizosaccharomyces pombe Proteins; D014404:Tubulin