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The E3 ligase Topors induces the accumulation of polysumoylated forms of DNA topoisomerase I in vitro and in vivo
Author(s) -
Hammer Eva,
Heilbronn Regine,
Weger Stefan
Publication year - 2007
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2007.10.040
Subject(s) - dna ligase , sumo protein , ubiquitin ligase , topoisomerase , in vitro , dna , ubiquitin , chemistry , in vivo , mutant , biochemistry , microbiology and biotechnology , biology , genetics , gene
Human Topors has originally been identified as binding partner of p53 and DNA topoisomerase I (TOP1). It can function as both an ubiquitin and SUMO‐1 E3 ligase for p53. Here we demonstrate that Topors enhances the formation of high‐molecular weight SUMO‐1 conjugates of TOP1 in a reconstituted in vitro system and also in human osteosarcoma cells, similar to treatment with CPT. In contrast to the situation observed with p53, overall sumoylation levels were rather unaffected. Experiments with TOP1 point mutants strongly suggest that the high‐molecular weight conjugates represent SUMO‐1 chains formed on a limited number of SUMO‐1 acceptor sites.