Distinct nuclear and spindle pole body populations of cyclin–cdc2 in fission yeast

Abstract

Cyclins, as subunits of the protein kinase encoded by the cdc2 gene are major controlling elements of the eukaryotic cell cycle. The fission yeast Schizosaccharomyces pombe has a B-type cyclin, which is a nuclear protein encoded by the cdc13 gene. Here we demonstrate the presence of two spatially distinct cdc13 cyclin populations in the nucleus of S. pombe, one of which is associated with the mitotic spindle poles. Both populations colocalize with the product of the cdc2 gene (p34cdc2). Treatment of cells with the antimicrotubule drug thiabendazole prevents cyclin degradation and blocks the tyrosine dephosphorylation and activation of cdc2. These results suggest a key regulatory role of the cdc2-cyclin complex in the initiation of mitotic spindle formation and also that mitotic microtubule function is required for cdc2 activation.

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

“…In (b), Rep1 was used for various deletion mutant genes. Fulllength and kinase activity was comparable to that in wild-type mitotic cells (Moreno et al 1989;Alfa et al 1990). Overproduction of Dis1 thus appeared to lead to the arrest with activated cdc2/cyclin B kinase.…”

Regulation and function of the interaction between the APC tumour suppressor protein and EB1

“…The involvement of p34 cdc2 in regulating the function of a spindle microtubule-associated protein such as EB1 is not unusual, as it has long been noted that p34 cdc2 activity is closely linked to mitotic microtubule function (i.e. Alfa et al, 1990;Andreassen et al, 1994;see Cassimeris, 1999 for a recent review). Furthermore, the association of tau protein with microtubules is also modi®ed during mitosis by phosphorylation at Ser-Pro and PKA consensus motifs (Illenberger et al, 1998).…”

An actin point‐mutation neighboring the ‘hydrophobic plug’ causes defects in the maintenance of cell polaroty and septum organization in the fission yeast Schizosaccharomyces pombe

“…Thus, it is entirely possible that cdc2 kinase activity might be affected, when cytoskeletal structures are significantly disturbed in certain ways, possibly due to changes in cellular localization of cdc2 kinase and/or its regulators (also see ref. [32]). This scenario is consistent with the previous observation that cps8 temperature lethality was substantially suppressed in a presence of adh-cdc25+ (over-expression of cdc25 +) [23].…”