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STRUCTURALLY DISTINCT UBIQUITIN- AND SUMO-MODIFIED PCNA: IMPLICATIONS FOR THEIR DISTINCT ROLES IN THE DNA DAMAGE RESPONSE
Journal article   Open access   Peer reviewed

STRUCTURALLY DISTINCT UBIQUITIN- AND SUMO-MODIFIED PCNA: IMPLICATIONS FOR THEIR DISTINCT ROLES IN THE DNA DAMAGE RESPONSE

Susan E Tsutakawa, Chunli Yan, Xiaojun Xu, Christopher P Weinacht, Bret D Freudenthal, Kun Yang, Zhihao Zhuang, M. Todd Washington, John A Tainer and Ivaylo Ivanov
Structure (London), Vol.23(4), pp.724-733
04/07/2015
DOI: 10.1016/j.str.2015.02.008
PMCID: PMC4394044
PMID: 25773143
url
https://doi.org/10.1016/j.str.2015.02.008View
Published (Version of record) Open Access

Abstract

Proliferating cell nuclear antigen (PCNA) is a pivotal replication protein, which also controls cellular responses to DNA damage. Posttranslational modification of PCNA by SUMO and ubiquitin modulate these responses. How the modifiers alter PCNA-dependent DNA repair and damage tolerance pathways is largely unknown. We used hybrid methods to identify atomic models of PCNA K107 -Ub and PCNA K164 -SUMO consistent with small angle X-ray scattering (SAXS) data of these complexes in solution. We show that SUMO and ubiquitin have distinct modes of association to PCNA. Ubiquitin adopts discrete docked binding positions. By contrast, SUMO associates by simple tethering and adopts extended flexible conformations. These structural differences are the result of the opposite electrostatic potentials of SUMO and Ub. The unexpected contrast in conformational behavior of Ub-PCNA and SUMO-PCNA has implications for interactions with partner proteins, interacting surfaces accessibility, and access points for pathway regulation.

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