Yeast ubiquitin-like genes are involved in duplication of the microtubule organizing center

• Published in: The Journal of cell biology 1996-06, Vol.133 (6), p.1331-1346
• Main Authors: Biggins, S. (University of California, San Francisco, CA.), Ivanovska, I, Rose, M.D
• Format: Article
• Language: English
• Subjects: Alleles; Amino Acid Sequence; Antibodies; Base Sequence; Calcium-Binding Proteins - analysis; Calcium-Binding Proteins - genetics; Cell cycle; Cell Cycle Proteins - analysis; Cell Cycle Proteins - genetics; Cell nucleus; Cells; Cellular biology; Centrosome - physiology; Centrosome - ultrastructure; Cloning, Molecular; COMPOSICION QUIMICA; COMPOSITION CHIMIQUE; DNA-Binding Proteins - physiology; ESTRUCTURA CELULAR; Fungal Proteins - analysis; Fungal Proteins - biosynthesis; Fungal Proteins - chemistry; Fungal Proteins - genetics; Fungal Proteins - physiology; GENE; GENES; Genes, Fungal - genetics; Genetic mutation; Molecular Sequence Data; Molecular Weight; MUTANT; MUTANTES; Mutation; Nuclear Proteins - genetics; Plasmids; Protein Processing, Post-Translational; PROTEINAS; PROTEINE; Proteins; Restriction Mapping; SACCHAROMYCES CEREVISIAE; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins; SECUENCIA NUCLEOTIDICA; Sequence Analysis, DNA; Sequence Homology, Amino Acid; SEQUENCE NUCLEOTIDIQUE; Spindle pole body; STRUCTURE CELLULAIRE; Ubiquitins; Ubiquitins - biosynthesis; Ubiquitins - chemistry; Ubiquitins - genetics; Ubiquitins - physiology; Yeast; Yeasts
• ISSN: 0021-9525; 1540-8140
• DOI: 10.1083/jcb.133.6.1331

KAR1 is required for duplication of the Saccharomyces cerevisiae microtubule organizing center, the spindle pole body (SPB) (Rose M.D., and G.R. Fink, 1987. Cell. 48:1047-1060). Suppressors of a kar1 allele defective for SPB duplication were isolated in two genes, CDC31 and DSK2 (Vallen, E.A., W.H., M. Winey, and M.D. Rose. 1994. Genetics. 137:407-422). To elucidate the role of DSK2 in SPB duplication, we cloned the gene and found it encodes a novel ubiquitin-like protein containing an NH2 terminus 36% identical to ubiquitin. The only other known yeast ubiquitin-like protein is encoded by the nucleotide excision repair gene RAD23 (Watkins, J.F., P. Sung, L. Prakash, and S. Prakash. 1993. Mol. Cell. Bio. 13:7757-7765). Unlike ubiquitin, the NH2-terminal domain of Dsk2p is not cleaved from the protein, indicating that Dsk2p is not conjugated to other proteins. Although the DSK2-1 mutation alters a conserved residue in the Dsk2p ubiquitin-like domain, we detect no differences in Dsk2p or Cdc31p stability. Therefore, DSK2 does not act by interfering with ubiquitin-dependent protein degradation of these proteins. Although DSK2 is not essential, a strain deleted for both DSK2 and RAD23 is temperature sensitive for growth due to a block in SPB duplication. In addition, overexpression of DSK2 is toxic, and the DSK2-1 allele causes a block in SPB duplication. Therefore, DSK2 dosage is critical for SPB duplication. We determined that CDC31 gene function is downstream of DSK2 and KAR1. Dsk2p is a nuclear-enriched protein, and we propose that Dsk2p assists in Cdc31 assembly into the new SPB