title: Yeast ubiquitin-like genes are involved in duplication of the microtubule organizing center.
abstract: 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.
authors.affiliation: Princeton University, Department of Molecular Biology, New Jersey 08544-1014, USA.
authors.forename: S
authors.initials: S
authors.lastname: Biggins
authors.forename: I
authors.initials: I
authors.lastname: Ivanovska
authors.forename: M D
authors.initials: MD
authors.lastname: Rose
mesh_terms: D000595:Amino Acid Sequence; D001483:Base Sequence; D002135:Calcium-Binding Proteins / Q000032:analysis / Q000235:genetics; D018797:Cell Cycle Proteins / Q000032:analysis / Q000235:genetics; D018385:Centrosome / Q000502:physiology* / Q000648:ultrastructure; D003001:Cloning, Molecular; D004268:DNA-Binding Proteins / Q000502:physiology; D005656:Fungal Proteins / Q000032:analysis / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics* / Q000502:physiology; D005800:Genes, Fungal / Q000235:genetics*; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009154:Mutation; D009687:Nuclear Proteins / Q000235:genetics; D011499:Protein Processing, Post-Translational; D015183:Restriction Mapping; D012441:Saccharomyces cerevisiae / Q000166:cytology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014452:Ubiquitins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics* / Q000502:physiology
chemical_list: C083769:CDC31 protein, S cerevisiae; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; C100415:DSK2 protein, S cerevisiae; D005656:Fungal Proteins; C074559:KAR1 protein, S cerevisiae; D009687:Nuclear Proteins; C490846:RAD23 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014452:Ubiquitins