Electronic Thesis and Dissertation Repository


Master of Science




Dr. Hong Ling


Elg1, the major component of an alternative PCNA loader, is vital in maintaining chromosomal stability. PCNA is an essential coordinator for DNA replication and the damage response through protein-protein interactions. The N-terminus of Elg1 interacts with PCNA and preferentially SUMOylated PCNA (sPCNA) and contains five putative motifs for PCNA and SUMO binding. How these motifs contribute to PCNA interactions is unclear. In this study, we biochemically characterized the interactions between Elg1 and PCNA and found that i) two PCNA-interacting protein boxes (PIP boxes) participate in the interaction with PCNA, which may be interfered by the SUMO-interacting motifs (SIMs); ii) the Elg1 N-terminus binds to sPCNA with micromolar affinity, and mutations on SIMs have subtle effects on the binding affinity; iii) all three SIMs interact with SUMO. Given these findings, we propose that Elg1’s interaction with PCNA is promoted by SIMs upon SUMOylation and inhibited by SIMs when lacks PCNA SUMOylation.

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Biochemistry Commons