Structural highlights
Function[SIZ2_YEAST] May act as an E3 ligase mediating SUMO/Smt3 attachment to septins. May be involved in chromosome maintenance.[1] [2] Publication Abstract from PubMedRepair of DNA double-stranded breaks by homologous recombination (HR) is dependent on DNA end resection and on post-translational modification of repair factors. In budding yeast, single-stranded DNA is coated by replication protein A (RPA) following DNA end resection, and DNA-RPA complexes are then SUMO-modified by the E3 ligase Siz2 to promote repair. Here, we show using enzymatic assays that DNA duplexes containing 3' single-stranded DNA overhangs increase the rate of RPA SUMO modification by Siz2. The SAP domain of Siz2 binds DNA duplexes and makes a key contribution to this process as highlighted by models and a crystal structure of Siz2 and by assays performed using protein mutants. Enzymatic assays performed using DNA that can accommodate multiple RPA proteins suggest a model in which the SUMO-RPA signal is amplified by successive rounds of Siz2-dependent SUMO modification of RPA and dissociation of SUMO-RPA at the junction between single- and double-stranded DNA. Our results provide insights on how DNA architecture scaffolds a substrate and E3 ligase to promote SUMO modification in the context of DNA repair. DNA asymmetry promotes SUMO modification of the single-stranded DNA-binding protein RPA.,Cappadocia L, Kochanczyk T, Lima CD EMBO J. 2021 Nov 15;40(22):e103787. doi: 10.15252/embj.2019103787. Epub 2021 Sep , 29. PMID:34585421[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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