The spindle pole body component Spc98p interacts with the gamma-tubulin-like Tub4p of Saccharomyces cerevisiae at the sites of microtubule attachment.
Tub4p is a novel tubulin found in Saccharomyces cerevisiae. It most resembles gamma-tubulin and, like it, is localized to the yeast microtubule organizing centre, the spindle pole body (SPB). In this paper we report the identification of SPC98 as a dosage-dependent suppressor of the conditional lethal tub4-1 allele. SPC98 encodes an SPB component of 98 kDa which is identical to the previously described 90 kDa SPB protein. Strong overexpression of SPC98 is toxic, causing cells to arrest with a large bud, defective microtubule structures, undivided nucleus and replicated DNA. The toxicity of SPC98 overexpression was relieved by co-overexpression of TUB4. Further evidence for an interaction between Tub4p and Spc98p came from the synthetic toxicity of tub4-1 and spc98-1 alleles, the dosage-dependent suppression of spc98-4 by TUB4, the binding of Tub4p to Spc98p in the two-hybrid system and the co-immunoprecipitation of Tub4p and Spc98p. In addition, Spc98-1p is defective in its interaction with Tub4p in the two-hybrid system. We suggest a model in which Tub4p and Spc98p form a complex involved in microtubule organization by the SPB.
Geissler
S
S
Max-Planck Institut für Biochemie, Am Klopferspitz 18a, Genzentrum, 82152 Martinsried, Germany.
Pereira
G
G
Spang
A
A
Knop
M
M
Souès
S
S
Kilmartin
J
J
Schiebel
E
E
D000595:Amino Acid Sequence; D002453:Cell Cycle; D002470:Cell Survival; D003001:Cloning, Molecular; D005656:Fungal Proteins / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D016153:Genes, Suppressor; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D010641:Phenotype; D010957:Plasmids / Q000378:metabolism; D011401:Promoter Regions, Genetic; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins; D008941:Spindle Apparatus / Q000378:metabolism*; D013696:Temperature; D014404:Tubulin / Q000378:metabolism*
D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; C100764:TUB4 protein, S cerevisiae; D014404:Tubulin