High impact information on Sse

• Therefore, we have screened for genetic loci that modify the aberrant phenotypes caused by overexpression of the regulatory separase complex subunits Pimples/securin and Three rows in Drosophila [1].
• While direct evidence for an involvement of this Drosophila Cenp-C homolog in separase activation at centromeres could not be obtained, in vivo imaging clearly demonstrated that it is required for normal attachment of kinetochores to the spindle [1].
• This lethality can be suppressed by a reduction of catalytically active SSE levels, indicating that THR cleavage inactivates SSE complexes [2].
• Proteolytic cleavage of the THR subunit during anaphase limits Drosophila separase function [2].
• Therefore, our genetic screen has identified all three components of the complex that regulates sister chromatid separation, and our observations indicate that interactions between Cdk1-CycB and the Pim-Thr-Sse complex are dosage sensitive [3].

Biological context of Sse

• THR cleavage is particularly important during the process of cellularization, which follows completion of the last syncytial mitosis of early embryogenesis, suggesting that Drosophila separase has other targets in addition to cohesin subunits [2].
• Furthermore, nuclei move slower during cortical migration in embryos with higher Cdk1-CycB activity, whereas reducing either Pim or Sse suppresses this phenotype by causing a novel nuclear migration pattern [3].
• Interestingly, however, pronounced defects in the epithelial organization develop in the following interphase, indicating that the separase complex is not only important for genetic stability but also and perhaps indirectly for epithelial integrity [4].
• The amount of meiotic cohesin's Rec8 subunit retained at centromeres after meiosis I is reduced in Deltasgo1, but not in Deltasgo2, cells, and Sgo1 appears to regulate cleavage of Rec8 by separase [5].

Enzymatic interactions of Sse

• These results indicate that THR is cleaved by SSE [2].

Other interactions of Sse

• Drosophila separase associates with regulatory subunits encoded by the pimples and three rows genes [4].

References