Ubiquitination of human AP-endonuclease 1 (APE1) enhanced by T233E substitution and by CDK5

Carlos S. Busso, Courtney M. Wedgeworth, Tadahide Izumi

Research output: Contribution to journalArticlepeer-review

22 Scopus citations


Apurinic/apyrimidinic endonuclease-1 (APE1) is a multifunctional DNA repair/gene regulatory protein in mammalian cells, and was recently reported to be phosphorylated at Thr233 by CDK5. We here report that ubiquitination of T233E APE1, a mimicry of phospho-T233 APE1, was markedly increased in multiple cell lines. Expression of CDK5 enhanced monoubiquitination of endogenous APE1. Polyubiquitinated APE1 was decreased when K48R ubiquitin was expressed, suggesting that polyubiquitination was mediated mainly through Lys48 of ubiquitin. The ubiquitination activity of MDM2, consistent in its role for APE1 ubiquitination, was increased for T233E APE1 compared to the wild-type APE1. In mouse embryonic fibroblasts lacking the MDM2 gene, ubiquitination of T233E APE1 was still observed probably because of the decreased degradation activity for monoubiquitinated APE1 and because of backup E3 ligases in the cells. Monoubiquitinated APE1 was present in the nucleus, and analyzing global gene expression profiles with or without induction of a ubiquitin-APE1 fusion gene suggested that monoubiquitination enhanced the gene suppression activity of APE1. These data reveal a delicate balance of ubiquitination and phosphorylation activities that alter the gene regulatory function of APE1.

Original languageEnglish
Pages (from-to)8017-8028
Number of pages12
JournalNucleic Acids Research
Issue number18
StatePublished - Oct 2011

ASJC Scopus subject areas

  • Genetics


Dive into the research topics of 'Ubiquitination of human AP-endonuclease 1 (APE1) enhanced by T233E substitution and by CDK5'. Together they form a unique fingerprint.

Cite this