Patronus is the elusive plant securin, preventing chromosome separation by antagonizing separase

Abstract

2 0 2 1 Chromosome distribution at anaphase of mitosis and meiosis is triggered by 2 2 separase, an evolutionarily conserved protease. Separase must be tightly regulated 2 3 to prevent the untimely release of chromatid cohesion and disastrous chromosome 2 4 distribution defects. Securin is the key inhibitor of separase in animals and fungi, but 2 5has not been identified in other eukaryotic lineages. Here, we identified PATRONUS1 2 6 and PATRONUS2 (PANS1 and PANS2) as the Arabidopsis homologues of securin. 7Disruption of PANS1 is known to lead to the premature separation of chromosomes 2 8 at meiosis, and the simultaneous disruption of PANS1 and PANS2 is lethal. Here, we 2 9show that PANS1 targeting by the anaphase-promoting-complex is required to trigger 3 0 chromosome separation, mirroring the regulation of securin. We showed that PANS1 3 1 acts independently from Shugosins. In a genetic screen for pans1 suppressors, we 3 2 identified SEPARASE mutants, showing that PANS1 and SEPARASE have 3 3 antagonistic functions in vivo. Finally, we showed that the PANS1 and PANS2 3 4 proteins interact directly with SEPARASE. Altogether, our results show that PANS1 3 5 and PANS2 act as a plant securin. Remote sequence similarity was identified 3 6 between the plant patronus family and animal securins, suggesting that they indeed 3 7 derive from a common ancestor. Identification of patronus as the elusive plant 3 8 securin illustrates the extreme sequence divergence of this central regulator of 3 9 mitosis and meiosis.4 0 4 1 3

Joint control of meiotic crossover patterning by the synaptonemal complex and HEI10 dosage

“…Immunolocalization on male meiocytes were conducted by modifying a previously described method 8,40 . Briefly, fresh 0.35-0.45 mm flower buds were dissected to remove sepals and petals and collected in buffer A (KCl 80 mM, NaCl 20 mM, Pipes-NaOH 15 mM, EGTA 0.5 mM, EDTA 2 mM, Sorbitol 80 mM, DTT 1 mM, Spermine 0.15 mM, spermidine 0.5 mM).…”

The FANCC-FANCE-FANCF complex is evolutionarily conserved and regulates meiotic recombination

“…Arabidopsis cell suspension cultures expressing N-terminal GSrhino-tagged FANCC and for C-terminal GSrhino-tagged FANCC were used for pull-down as previously described (Van Leene et al 2019; Cromer et al 2019). Co-purified proteins were identified using standard protocols utilizing on bead-digested sample evaluated on a Q Exactive mass spectrometer (Thermo Fisher Scientific) (Van Leene et al 2015).…”

Plant lineage-specific PIKMIN1 drives APC/CCCS52A2 E3-ligase activity-dependent cell division

“…Various A-and B-type CYCs have indeed been implicated in being targeted by the APC/C in plants, with evidence being most comprehensive for CYCA2;3 (Boudolf et al, 2009;Heyman et al, 2011;Eloy et al, 2012;Xu et al, 2016), CYCA3;4 (Fülöp et al, 2005;Willems et al, 2020), and CYCB1;1 (Kwee and Sundaresan, 2003;Fülöp et al, 2005;Rojas et al, 2009;Eloy et al, 2011;Zheng et al, 2011;Wang et al, 2012;Wang et al, 2013;Guo et al, 2016). Other cell division-related proteins characterized to be APC/C substrates include the cell wall biosynthesis gene CELLULOSE SYNTHASE LIKE-D 5 (CSLD5) (Gu et al, 2016), the rice protein ROOT ARCHITECTURE ASSOCIATED 1 (RAA1, known as FLOWERING-PROMOTING FACTOR 1 [FPF1] in Arabidopsis) that interacts with the spindle and inhibits metaphase-to-anaphase transitions (Ge et al, 2004;Han et al, 2008;Xu et al, 2010), and the Arabidopsis PATRONUS1 (PANS1) and rice RICE SALT SENSITIVE 1 (RSS1) proteins that are essential for sister chromatid cohesion during the early stages of cell division (Ogawa et al, 2011;Cromer et al, 2013;Juraniec et al, 2016;Cromer et al, 2019). Several other proteins indirectly related to the cell division process have been implicated to be APC/C targets as well, including the DSRNA-BINDING PROTEIN 4 (DRB4) involved in RNA silencing (Marrocco et al, 2012), the transcription factor ETHYLENE RESPONSE FACTOR 115 (ERF115) that controls QC divisions in the root tip (Heyman et al, 2013), the rice transcription factor MONOCULM 1 (MOC1, called SCARECROW-LIKE 18/LATERAL SUPPRESSOR [SCL18/LAS] in Arabidopsis) involved in shoot branching (Lin et al, 2012;Xu et al, 2012;Lin et al, 2020), the rice homolog of the SHORT ROOT (OsSHR) transcription factor involved in root growth (Lin et al, 2020), the rice RCAR family of abscisic acid receptors (Lin et al, 2015), and the DDR-complex subunit DEFECTIVE IN MERISTEM SILENCING 3 (DMS3) involved in the silencing of transposable elements (Zhong et al, 2019).…”