High impact information on SPO12

• A strain homozygous for an insertion which removes the complementarity between the SPO12 and SPO16 mRNAs has an efficiency of sporulation, number of spores per ascus, and spore viability identical to those of a wild-type strain [1].
• The SPO12 gene, which is required for meiosis I chromosome division during sporulation of the yeast Saccharomyces cerevisiae, has been isolated [1].
• DNA sequencing has identified an open reading frame of 173 codons that encodes the putative SPO12 protein and has no significant sequence similarities to known genes [1].
• Inducible growth control genes include those in the TOR signaling pathway and SPO12, whereas PKC1 is downregulated [2].
• RESULTS: Here we investigate how the FEAR network component Spo12 regulates Cdc14 activation [3].

Biological context of SPO12

• Our results show that Cdc14, Slk19, and Spo12 are not only required for meiosis I spindle disassembly but also play a pivotal role in establishing two consecutive chromosome segregation phases, a key feature of the meiotic cell cycle [4].
• We have performed a genetic and biochemical analysis of the SPO12 gene, which regulates meiotic nuclear divisions in budding yeast [5].
• Since high-copy SPO12 is able to suppress a wide variety of mitotic exit mutants, all of which arrest with high Clb-Cdc28 activity, we speculated whether SPO12 is able to facilitate exit from mitosis when overexpressed by antagonizing mitotic kinase activity [6].
• Interestingly, SPO12, which is involved in the release of Cdc14 from the nucleolus during early anaphase, also became essential in cdc15-2 kap104-E604K cells at a high temperature [7].
• In this context, the overexpression of a FEAR component, SPO12, in a MEN mutant background enhances the ability of MEN mutants to bypass cell cycle arrest [8].

Anatomical context of SPO12

• A complex containing Spo12p and Kap121p was isolated from cytosol and was also reconstituted with recombinant proteins, indicating that this interaction is direct [9].

Physical interactions of SPO12

• Here we present genetic evidence that nonfunctional mutant Dbf2 protein blocks the function of Dbf20 protein by sequestering a common interacting protein encoded by SPO12 [10].
• Finally, we show that Spo12 phosphorylation is cell cycle regulated and affects its binding to Fob1 [3].

Regulatory relationships of SPO12

• Even a single extra copy of SPO12 is sufficient to suppress the dbf2 defect [10].
• This delocalization of Cdc14 was suppressed by the deletion of SPO12 [7].
• Spo12 protein level is regulated by the APC and the protein is degraded in G1 by an Hct1-dependent mechanism [6].

Other interactions of SPO12

• The Spo12 and Slk19 proteins have been implicated in regulating meiosis I kinetochore orientation and/or in preventing cleavage of Rec8 at centromeres [11].
• Consistent with this a synthetic interaction was observed between pho85delta and strains deleted for SIC1, SWI5, and SPO12 [12].
• We observed that a spo12 mutation is synthetically lethal in vegetative cells with a mutation in HCT1, a gene necessary for cells to exit mitosis, suggesting that Spo12p may have a role in exit from mitosis [5].
• We identify the replication fork block protein Fob1 as a Spo12-interacting factor [3].
• We found that Spo12p is imported into the nucleus by the karyopherin Kap121p [9].

Analytical, diagnostic and therapeutic context of SPO12

• Finally, site-directed mutagenesis of highly conserved residues in the Spo12 protein sequence abolishes both its mitotic suppressor activity as well as its meiotic function [6].

References