Role of Cdc48/p97 as a SUMO-targeted segregase curbing Rad51–Rad52 interaction

Abstract

Cdc48 (also known as p97), a conserved chaperone-like ATPase, plays a strategic role in the ubiquitin system. Empowered by ATP-driven conformational changes, Cdc48 acts as a segregase by dislodging ubiquitylated proteins from their environment. Ufd1, a known co-factor of Cdc48, also binds SUMO (ref. 6), but whether SUMOylated proteins are subject to the segregase activity of Cdc48 as well and what these substrates are remains unknown. Here we show that Cdc48 with its co-factor Ufd1 is SUMO-targeted to proteins involved in DNA double-strand break repair. Cdc48 associates with SUMOylated Rad52, a factor that assembles the Rad51 recombinase on chromatin. By acting on the Rad52-Rad51 complex, Cdc48 curbs their physical interaction and displaces the proteins from DNA. Genetically interfering with SUMO-targeting or segregase activity leads to an increase in spontaneous recombination rates, accompanied by aberrant in vivo Rad51 foci formation in yeast and mammalian cells. Our data thus suggest that SUMO-targeted Cdc48 restricts the recombinase Rad51 by counterbalancing the activity of Rad52. We propose that Cdc48, through its ability to associate with co-factors that have affinities for ubiquitin and SUMO, connects the two modification pathways for protein degradation or other regulatory purposes.

The AAA-ATPase molecular chaperone Cdc48/p97 disassembles sumoylated centromeres, decondenses heterochromatin, and activates ribosomal RNA genes

“…Here, we describe the active mechanism for the removal of CenH3 from centromeres. Recent studies have shown that sumoylation, as well as ubiquitination, can be a signal for protein removal from complexes and transference into degradation pathways (32,33). Our results demonstrate that CenH3 is subjected to sumoylation and provide evidence for the CDC48A NPL4 -directed centromere disassembly through active unloading of sumoylated CenH3 from native centromeres.…”

Pli1PIAS1 SUMO Ligase Protected by the Nuclear Pore-associated SUMO Protease Ulp1SENP1/2

“…As in fission yeast (44,45), budding yeast Cdc48 also acts as a SUMO-targeted segregase that removes sumoylated DNA repair factors from chromatin (59). Given this degree of functional conservation, it seems likely that the human STUbL RNF4 and p97 cooperate in the remodeling of chromatin e.g.…”

The VCP/p97 system at a glance: connecting cellular function to disease pathogenesis

“…Whereas these are all functions that are mediated by its heterodimeric adaptor Ufd1-Npl4, VCP/p97 also cooperates with DVC1 (also known as SPRTN) to extract ubiquitylated DNA polymerase g and rescue stalled replication forks (Davis et al, 2012;Mosbech et al, 2012) in human cells. By contrast, VCP/p97 in budding yeast is targeted to the Rad512Rad52 complex by modification of Rad52 with the ubiquitin-like modifier SUMO during homologous recombination, to curb the binding of Rad51 to chromatin (Bergink et al, 2013). In addition, VCP/p97 promotes the G1/S transition by facilitating Far1 degradation in budding yeast, regulates spindle dynamics and limits the association of Aurora A with centrosomes in nematodes and human cells (Cao et al, 2003;Fu et al, 2003;Kress et al, 2013).…”

“…VCP/p97 has been associated with monoubiquitin, lysine-29, lysine-63 and lysine-48 chains, as well as branched lysine-11/48-linked chains (Ye, 2006;Meyer and Rape, 2014) (and see main text). In addition to ubiquitin, VCP/p97 has been linked to other ubiquitin-like modifiers, Nedd8 and SUMO, which it binds through the UBXD7 and (at least in budding yeast) Ufd1 adaptors, respectively Bergink et al, 2013).…”