112 Structurally distinct ubiquitin- and SUMO-modified PCNA: implications for their distinct roles in the DNA damage response

摘要: SUMMARY 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 PCNAdependent repair damage tolerance pathways largely unknown. We used hybrid methods identify atomic models PCNAK107-Ub PCNAK164-SUMO consistent with small-angle X-ray scattering data complexes in solution. show that have distinct modes association PCNA. Ubiquitin adopts discrete docked binding positions. By contrast, associates simple tethering extended flexible conformations. These structural differences are result opposite electrostatic potentials Ub. The unexpected contrast conformational behavior Ub-PCNA SUMO-PCNA has implications for interactions partner proteins, interacting surfaces accessibility, access points pathway regulation.