5mav
From Proteopedia
Crystal structure of human PCNA in complex with PARG (poly(ADP-ribose) glycohydrolase) peptide.
Structural highlights
FunctionPCNA_HUMAN Auxiliary protein of DNA polymerase delta and is involved in the control of eukaryotic DNA replication by increasing the polymerase's processibility during elongation of the leading strand. Induces a robust stimulatory effect on the 3'-5' exonuclease and 3'-phosphodiesterase, but not apurinic-apyrimidinic (AP) endonuclease, APEX2 activities. Has to be loaded onto DNA in order to be able to stimulate APEX2. Plays a key role in DNA damage response (DDR) by being conveniently positioned at the replication fork to coordinate DNA replication with DNA repair and DNA damage tolerance pathways. Acts as a loading platform to recruit DDR proteins that allow completion of DNA replication after DNA damage and promote postreplication repair: Monoubiquitinated PCNA leads to recruitment of translesion (TLS) polymerases, while 'Lys-63'-linked polyubiquitination of PCNA is involved in error-free pathway and employs recombination mechanisms to synthesize across the lesion.[1] [2] Publication Abstract from PubMedPoly(ADP-ribose) glycohydrolase (PARG) regulates cellular poly(ADP-ribose) (PAR) levels by rapidly cleaving glycosidic bonds between ADP-ribose units. PARG interacts with proliferating cell nuclear antigen (PCNA) and is strongly recruited to DNA damage sites in a PAR- and PCNA-dependent fashion. Here we identified PARG acetylation site K409 that is essential for its interaction with PCNA, its localization within replication foci and its recruitment to DNA damage sites. We found K409 to be part of a non-canonical PIP-box within the PARG disordered regulatory region. The previously identified putative N-terminal PIP-box does not bind PCNA directly but contributes to PARG localization within replication foci. X-ray structure and MD simulations reveal that the PARG non-canonical PIP-box binds PCNA in a manner similar to other canonical PIP-boxes and may represent a new type of PIP-box. While the binding of previously described PIP-boxes is based on hydrophobic interactions, PARG PIP-box binds PCNA via both stabilizing hydrophobic and fine-tuning electrostatic interactions. Our data explain the mechanism of PARG-PCNA interaction through a new PARG PIP-box that exhibits non-canonical sequence properties but a canonical mode of PCNA binding. A novel non-canonical PIP-box mediates PARG interaction with PCNA.,Kaufmann T, Grishkovskaya I, Polyansky AA, Kostrhon S, Kukolj E, Olek KM, Herbert S, Beltzung E, Mechtler K, Peterbauer T, Gotzmann J, Zhang L, Hartl M, Zagrovic B, Elsayad K, Djinovic-Carugo K, Slade D Nucleic Acids Res. 2017 Sep 19;45(16):9741-9759. doi: 10.1093/nar/gkx604. PMID:28934471[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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