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Crystal structure of PCNA in complex with DNA polymerase iota fragment
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] Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedTranslesion synthesis (TLS) is a DNA damage tolerance mechanism that allows continued DNA synthesis, even in the presence of damaged DNA templates. Mammals have multiple DNA polymerases specialized for TLS, including Poleta, Poliota, and Polkappa. These enzymes show preferential bypass for different lesions. Proliferating cell nuclear antigen (PCNA), which functions as a sliding clamp for the replicative polymerase Poldelta, also interacts with the three TLS polymerases. Although many PCNA-binding proteins have a highly conserved sequence termed the PCNA-interacting protein box (PIP-box), Poleta, Poliota, and Polkappa have a noncanonical PIP-box sequence. In response to DNA damage, Lys-164 of PCNA undergoes ubiquitination by the RAD6-RAD18 complex, and the ubiquitination is considered to facilitate TLS. Consistent with this, these three TLS polymerases have one or two ubiquitin binding domains and are recruited to replication forks via interactions with ubiquitinated PCNA involving the noncanonical PIP-box and ubiquitin binding domain. However, it is unclear how these TLS polymerases interact with PCNA. To address the structural basis for interactions between different TLS polymerases and PCNA, we determined crystal structures of PCNA bound to peptides containing the noncanonical PIP-box of these polymerases. We show that the three PIP-box peptides interact with PCNA in different ways, both from one another and from canonical PIP-box peptides. Especially, the PIP-box of Poliota adopts a novel structure. Furthermore, these structures enable us to speculate how these TLS polymerases interact with Lys-164-monoubiquitinated PCNA. Our results will provide clues to understanding the mechanism of preferential recruitment of TLS polymerases to the stalled forks. Structural basis for novel interactions between human translesion synthesis polymerases and proliferating cell nuclear antigen.,Hishiki A, Hashimoto H, Hanafusa T, Kamei K, Ohashi E, Shimizu T, Ohmori H, Sato M J Biol Chem. 2009 Apr 17;284(16):10552-60. Epub 2009 Feb 10. PMID:19208623[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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