Abstract
RIF1 was originally identified as a telomeric protein in budding yeast, but is now known to play diverse roles in chromosome stability throughout eukaryotes. RIF1 regulates initiation time of a subset of replication origins in fission yeast and mammalian cells.
Replication origin initiation requires activation of the MCM helicase through phosphorylation of MCM subunits by Dbf4-Dependent Kinase (DDK). We previously demonstrated that budding yeast Rif1 directs Protein Phosphatase 1 (PP1) to counteract phosphorylation of Mcm4, negatively regulating DNA replication in S. cerevisiae and ensuring cell cycle control over MCM complex activation.
PP1 interaction motifs are a conserved feature of RIF1 proteins, and human RIF1 has been reported to bind PP1. To test whether mammalian RIF1 regulates DNA replication by targeting PP1 activity, we have investigated the effects of mutating the PP1-interaction motifs in the human RIF1 protein. We find that PP1 interaction-defective RIF1 cannot substitute for wild-type RIF1 in controlling phosphorylation levels of human MCM complex proteins.
Our data support the idea that like yeast Rif1, the human RIF1 protein is a PP1 substrate-targeting subunit that regulates DNA replication by recruiting PP1 to counteract DDK-mediated phosphorylation. This replication regulatory mechanism therefore appears to be conserved from yeast to mammals.
Replication origin initiation requires activation of the MCM helicase through phosphorylation of MCM subunits by Dbf4-Dependent Kinase (DDK). We previously demonstrated that budding yeast Rif1 directs Protein Phosphatase 1 (PP1) to counteract phosphorylation of Mcm4, negatively regulating DNA replication in S. cerevisiae and ensuring cell cycle control over MCM complex activation.
PP1 interaction motifs are a conserved feature of RIF1 proteins, and human RIF1 has been reported to bind PP1. To test whether mammalian RIF1 regulates DNA replication by targeting PP1 activity, we have investigated the effects of mutating the PP1-interaction motifs in the human RIF1 protein. We find that PP1 interaction-defective RIF1 cannot substitute for wild-type RIF1 in controlling phosphorylation levels of human MCM complex proteins.
Our data support the idea that like yeast Rif1, the human RIF1 protein is a PP1 substrate-targeting subunit that regulates DNA replication by recruiting PP1 to counteract DDK-mediated phosphorylation. This replication regulatory mechanism therefore appears to be conserved from yeast to mammals.
Original language | English |
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Publication status | Published - Jul 2015 |
Event | EMBO conference on DNA replication, chromosome segregation and cell division - England, Egham, United Kingdom Duration: 27 Jul 2015 → 31 Jul 2015 |
Conference
Conference | EMBO conference on DNA replication, chromosome segregation and cell division |
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Country/Territory | United Kingdom |
City | Egham |
Period | 27/07/15 → 31/07/15 |