High impact information on DBF2

• Moreover, Sdb25 protein levels and associated kinase activity are sharply up-regulated at the peak of Dbf2 kinase activity in cells released from a dbf2 ts block [1].
• The Saccharomyces cerevisiae protein kinase Dbf2 carries out an essential function in late mitosis, and its kinase activity is cell-cycle regulated around anaphase/telophase [1].
• We investigated the function of two S. cerevisiae proteins related to the MEN proteins Mob1p and Dbf2p kinase [2].
• Previous work indicates that cells lacking the Dbf2p-related protein Cbk1p fail to sustain polarized growth during early bud morphogenesis and mating projection formation (Bidlingmaier, S., E.L. Weiss, C. Seidel, D.G. Drubin, and M. Snyder. 2001. Mol. Cell. Biol. 21:2449-2462) [2].
• Our data now point to the protein kinase Mps1p triggering a new parallel branch of the spindle checkpoint in which Bub2p blocks Dbf2p function [3].

Biological context of DBF2

• Thus, Cdc15 promotes the exit from mitosis by directly switching on the kinase activity of Dbf2 [4].
• In cells lacking BUB2, Dbf2 localized to SPBs in cell cycle stages other than anaphase and telophase and Dbf2 kinase was prematurely active during metaphase [5].
• Dbf2 also localizes to SPBs during anaphase, which coincides with activation of Dbf2 kinase activity [5].
• Spo12 is a limiting factor that interacts with the cell cycle protein kinases Dbf2 and Dbf20, which are involved in mitotic chromatid disjunction [6].
• Indeed, physical analysis of chromosome copy number in dbf2 revertants able to grow at 37 degrees showed that the frequency of chromosome VIII acquisition increased when cells were incubated at the restrictive temperature, and reached a frequency of more than 100-fold the amount in wild-type yeast [6].

Anatomical context of DBF2

• Dbf2 is found on the centrosomes/spindle pole bodies (SPBs) and also at the bud neck where it forms a double ring [7].

Associations of DBF2 with chemical compounds

• Maize DRE-binding proteins DBF1 and DBF2 are involved in rab17 regulation through the drought-responsive element in an ABA-dependent pathway [8].
• The kinase activity is specific for serine/threonine residues and Dbf2 accounts for the bulk of the activity, with Dbf20 playing a minor role [9].
• Dbf2 is implicated in a Cbt1-dependent pathway following a shift from glucose to galactose or non-fermentable carbon sources in Saccharomyces cerevisiae [10].

Physical interactions of DBF2

• DBF2 binds MOB1 in vivo and can bind it in vitro in the absence of other yeast proteins [11].
• DNA-binding preferences of DBFs were analysed by electrophoretic mobility shift assays, and showed that both DBF1 and DBF2 bound to the wild-type DRE2 element, but not to the DRE2 mutant or to the DRE1 element which differs only in a single nucleotide [8].

Enzymatic interactions of DBF2

• We propose that Mob1 promotes this activation process by enabling Cdc15 to phosphorylate the critical Ser-374 and Thr-544 phosphoacceptor sites of Dbf2 [4].

Co-localisations of DBF2

• Here we present evidence that the MEN protein kinase complex Mob1p-Dbf2p localizes to mitotic nuclei and partially colocalizes with Cdc14p and kinetochore proteins [12].

Regulatory relationships of DBF2

• Even a single extra copy of SPO12 is sufficient to suppress the dbf2 defect [6].
• The neck localization, but not SPB localization, of Dbf2 was inhibited by the Bub2 spindle checkpoint [13].

Other interactions of DBF2

• Regulation of the mitotic exit protein kinases Cdc15 and Dbf2 [5].
• The DBF2 and DBF20 genes of the budding yeast Saccharomyces cerevisiae encode a pair of structurally similar protein kinases [6].
• Since SPO12 appears to encode a limiting factor, it may be a rate limiting cofactor that is involved in the regulation of the Dbf2 and Dbf20 protein kinases [6].
• The Cdc14 phosphatase is functionally associated with the Dbf2 protein kinase in Saccharomyces cerevisiae [14].
• As a component of the multisubunit CCR4 transcriptional complex, DBF2 is also involved in the regulation of gene expression [11].

Analytical, diagnostic and therapeutic context of DBF2

• Analysis of mRNA accumulation profiles showed that DBF1 is induced during maize embryogenesis and after desiccation, NaCl and ABA treatments in plant seedlings, whereas the DBF2 mRNA is not induced [8].

References