p93dis1, which is required for sister chromatid separation, is a novel microtubule and spindle pole body-associating protein phosphorylated at the Cdc2 target sites.

Abstract

Fission yeast cold-sensitive (cs) disl mutants are defective in sister chromatid separation. The dis1 + gene was isolated by chromosome walking. The null mutant showed the same phenotype as that of cs mutants. The d/s/+ gene product was identified as a novel 93-kD protein, and its localization was determined by use of anti-disl antibodies and green fluorescent protein (GFP) tagged to the carboxyl end of p93 dis1. The tagged p93 dlsl in living cells localizes along cytoplasmic microtubule arrays in interphase and the elongating anaphase spindle in mitosis, but association with the short metaphase spindle microtubules is strikingly reduced. In the spindle, the tagged p93 ais~ is enriched at the spindle pole bodies (SPBs). Time-lapse video images of single cells support the localization shift of p93 dis~ to the SPBs in metaphase and spindle microtubules in anaphase. The carboxy-terminal fragment, which is essential for Disl function, accumulates around the mitotic SPB. We propose that these localization shifts of p93 dis~ in mitosis facilitates sister chromatid separation by affecting SPB and anaphase spindle function.

Dissection of fission yeast microtubule associating protein p93Dis1: regions implicated in regulated localization and microtubule interaction

“…8a), and similar to that of the microtubule binding regions of MAP4 and tau (Aizawa et al 1991;Kanai et al 1992). There are three Cdc2 kinase sites in the region which are phosphorylated (Nabeshima et al 1995). The central region may interact directly with the acidic C-terminus of tubulin molecules conserved in S. pombe Hiraoka et al 1984).…”

“…2b; Nabeshima et al 1995). M, I and P in the figure indicate cells in mitosis, interphase and post-anaphase, respectively.…”

“…Dis1-GFP in living cells was located along cytoplasmic microtubules in interphase and the elongating spindle in mitosis, and also concentrated at the mitotic spindle pole bodies (SPBs) and the cell equator during septation/ cytokinesis (Nabeshima et al 1995). The extent of association with spindle microtubules was minimal in metaphase.…”

“…The number of amino acids for each polypeptide is indicated in the figure. To make 1 Kpn/Bam, 179 amino acids were internally deleted (Nabeshima et al 1995).…”

Mis3 with a conserved RNA binding motif is essential for ribosome biogenesis and implicated in the start of cell growth and S phase checkpoint

“…The double mutants between mis3-224 (Takahashi et al e1994) and various mutations noted below were constructed; cdc2-33, cdc6-121, cdc13-117, cdc25-22, cdc10-129 (Nurse et al 1976), cdc2-3w (Enoch et al 1992), Dcyc17/cig2 (Obara-Ishihara & Okayama 1994), Dmik1 (Lundgren et al 1991), wee1-50 (Russell & Nurse 1987), cdc16-116 (Fankhauser et al 1993), cdc17-K42, cdc18-K46 (Nasmyth & Nurse 1981), cdc22-C1 (Fernandez Sarabia et al 1993), swi7-H4 (Singh & Klar 1993), mis5-268, mis11-453 (Takahashi et al 1994, Drad3, Drad9, Drad17, Drad24, Drad25, Dchk1 (Al-Khodairy et al 1994), cut5-T401 (Saka et al 1994), Dcds1 (Murakami & Okayama 1995), Ddis1 (Nabeshima et al 1995), dis3-54 (Kinoshita et al 1991), dis2-11, Ddis2 (Ohkura et al 1989), cut1-21, cut2-364 (Funabiki et al 1996, cut9 (Yamada et al 1997), Dppa1, Dppa2 (Kinoshita et al 1993),Dpck1 (Toda et al 1993), Dtop1, top2-191 (Uemura & Yanagida 1984), and Ddsk1 mutants (Takeuchi & Yanagida 1993). The Mis3-HA integrant was obtained by integrating the HA-tagged mis3 gene at the carboxyl-terminus to replace the genomic mis3 locus.…”