The plant Spc98p homologue colocalizes with gamma-tubulin at microtubule nucleation sites and is required for microtubule nucleation.
The molecular basis of microtubule nucleation is still not known in higher plant cells. This process is better understood in yeast and animals cells. In the yeast spindle pole body and the centrosome in animal cells, gamma-tubulin small complexes and gamma-tubulin ring complexes, respectively, nucleate all microtubules. In addition to gamma-tubulin, Spc98p or its homologues plays an essential role. We report here the characterization of rice and Arabidopsis homologues of SPC98. Spc98p colocalizes with gamma-tubulin at the nuclear surface where microtubules are nucleated on isolated tobacco nuclei and in living cells. AtSpc98p-GFP also localizes at the cell cortex. Spc98p is not associated with gamma-tubulin along microtubules. These data suggest that multiple microtubule-nucleating sites are active in plant cells. Microtubule nucleation involving Spc98p-containing gamma-tubulin complexes could then be conserved among all eukaryotes, despite differences in structure and spatial distribution of microtubule organizing centers.
Erhardt
Mathieu
M
Institut de Biologie Moléculaire des Plantes, Centre National de la Recherche Scientifique UPR 2357, Université Louis Pasteur, 12 rue du Général Zimmer F-67084, Strasbourg Cedex, France.
Stoppin-Mellet
Virginie
V
Campagne
Sarah
S
Canaday
Jean
J
Mutterer
Jérôme
J
Fabian
Tanja
T
Sauter
Margret
M
Muller
Thierry
T
Peter
Christine
C
Lambert
Anne-Marie
AM
Schmit
Anne-Catherine
AC
D017360:Arabidopsis; D029681:Arabidopsis Proteins / Q000378:metabolism*; D002451:Cell Compartmentation / Q000502:physiology; D002453:Cell Cycle / Q000502:physiology*; D002467:Cell Nucleus / Q000378:metabolism*; D002478:Cells, Cultured / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000502:physiology; D049452:Green Fluorescent Proteins; D015151:Immunoblotting; D008164:Luminescent Proteins; D008869:Microtubule-Associated Proteins / Q000378:metabolism*; D008870:Microtubules / Q000378:metabolism*; D008969:Molecular Sequence Data; D009685:Nuclear Envelope / Q000378:metabolism; D012275:Oryza; D059828:Plant Cells; D010944:Plants / Q000378:metabolism*; D011993:Recombinant Fusion Proteins; D017386:Sequence Homology, Amino Acid; D014026:Nicotiana; D014404:Tubulin / Q000378:metabolism*
D029681:Arabidopsis Proteins; D008164:Luminescent Proteins; D008869:Microtubule-Associated Proteins; D011993:Recombinant Fusion Proteins; C112306:TUBGCP3 protein, human; D014404:Tubulin; D049452:Green Fluorescent Proteins