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Human RIF 1 and protein phosphatase 1 stimulate DNA replication origin licensing but suppress origin activation
Author(s) -
Hiraga Shinichiro,
Ly Tony,
Garzón Javier,
Hořejší Zuzana,
Ohkubo Yoshinobu,
Endo Akinori,
Obuse Chikashi,
Boulton Simon J,
Lamond Angus I,
Donaldson Anne D
Publication year - 2017
Publication title -
embo reports
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 4.584
H-Index - 184
eISSN - 1469-3178
pISSN - 1469-221X
DOI - 10.15252/embr.201641983
Subject(s) - dna replication , origin recognition complex , microbiology and biotechnology , seqa protein domain , biology , pre replication complex , protein phosphatase 1 , phosphorylation , helicase , minichromosome maintenance , protein subunit , dna replication factor cdt1 , licensing factor , eukaryotic dna replication , phosphatase , dna , biochemistry , gene , rna
The human RIF 1 protein controls DNA replication, but the molecular mechanism is largely unknown. Here, we demonstrate that human RIF 1 negatively regulates DNA replication by forming a complex with protein phosphatase 1 ( PP 1) that limits phosphorylation‐mediated activation of the MCM replicative helicase. We identify specific residues on four MCM helicase subunits that show hyperphosphorylation upon RIF 1 depletion, with the regulatory N‐terminal domain of MCM 4 being particularly strongly affected. In addition to this role in limiting origin activation, we discover an unexpected new role for human RIF 1‐ PP 1 in mediating efficient origin licensing. Specifically, during the G1 phase of the cell cycle, RIF 1‐ PP 1 protects the origin‐binding ORC 1 protein from untimely phosphorylation and consequent degradation by the proteasome. Depletion of RIF 1 or inhibition of PP 1 destabilizes ORC 1, thereby reducing origin licensing. Consistent with reduced origin licensing, RIF 1‐depleted cells exhibit increased spacing between active origins. Human RIF 1 therefore acts as a PP 1‐targeting subunit that regulates DNA replication positively by stimulating the origin licensing step, and then negatively by counteracting replication origin activation.