DNA and Chromosomes
Human ELG1 Regulates the Level of Ubiquitinated Proliferating Cell Nuclear Antigen (PCNA) through Its Interactions with PCNA and USP1*

https://doi.org/10.1074/jbc.M109.092544Get rights and content
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The level of monoubiquitinated proliferating cell nuclear antigen (PCNA) is closely linked with DNA damage bypass to protect cells from a high level of mutagenesis. However, it remains unclear how the level of monoubiquitinated PCNA is regulated. Here, we demonstrate that human ELG1 protein, which comprises an alternative replication factor C (RFC) complex and plays an important role in preserving genomic stability, as an interacting partner for the USP1 (ubiquitin-specific protease 1)-UAF1 (USP1-associated factor 1) complex, a deubiquitinating enzyme complex for PCNA and FANCD2. ELG1 protein interacts with PCNAs that are localized at stalled replication forks. ELG1 knockdown specifically resulted in an increase in the level of PCNA monoubiquitination without affecting the level of FANCD2 ubiquitination. It is a novel function of ELG1 distinct from its role as an alternative RFC complex because knockdowns of any other RFC subunits or other alternative RFCs did not affect PCNA monoubiquitination. Lastly, we identified a highly conserved N-terminal domain in ELG1 that was responsible for the USP1-UAF1 interaction as well as the activity to down-regulate PCNA monoubiquitination. Taken together, ELG1 specifically directs USP1-UAF1 complex for PCNA deubiquitination.

Deubiquitination
DNA Damage
DNA Repair
DNA Replication
Ubiquitination

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*

This work was supported, in whole or in part, by National Institutes of Health Grants RO1-HL52725, RO1-DK43889, and PO1-CA092584 (to A. D.) and National Institutes of Health, National Human Genome Research Institute, Intramural Research Program Grant HG012003-07 (to K. M.). This work was also supported by Korea Research Foundation Grant KRF-2007-357-C00092 funded by the Korean Government (to K. Y. L.).

1

A Harvard University Presidential Scholar.

2

Present address: Dept. of Biochemistry, University of Oxford, South Parks Rd., Oxford OX1 3QU, United Kingdom.