title: ATM-mediated serine 72 phosphorylation stabilizes ribonucleotide reductase small subunit p53R2 protein against MDM2 to DNA damage.
abstract: Ribonucleotide reductase small subunit p53R2 was identified as a p53 target gene that provides dNTP for DNA damage repair. However, the slow transcriptional induction of p53R2 in RNA may not be rapid enough for prompt DNA damage repair, which has to occur within a few hours of damage. Here, we demonstrate that p53R2 becomes rapidly phosphorylated at Ser(72) by ataxia telangiectasia mutated (ATM) within 30 min after genotoxic stress. p53R2, as well as its heterodimeric partner RRM1, are associated with ATM in vivo. Mutational studies further indicate that ATM-mediated Ser(72) phosphorylation is essential for maintaining p53R2 protein stability and conferring resistance to DNA damage. The mutation of Ser(72) on p53R2 to alanine results in the hyperubiquitination of p53R2 and reduces p53R2 stability. MDM2, a ubiquitin ligase for p53, interacts and facilitates ubiquitination of the S72A-p53R2 mutant more efficiently than WT-p53R2 after DNA damage in vivo. Our results strongly suggest a novel mechanism for the regulation of p53R2 activity via ATM-mediated phosphorylation at Ser(72) and MDM2-dependent turnover of p53R2 dephosphorylated at the same residue.
authors.affiliation: Department of Clinical and Molecular Pharmacology, City of Hope National Medical Center, Duarte, CA 91010-3000, USA. lchang@coh.org
authors.forename: Lufen
authors.initials: L
authors.lastname: Chang
authors.forename: Bingsen
authors.initials: B
authors.lastname: Zhou
authors.forename: Shuya
authors.initials: S
authors.lastname: Hu
authors.forename: Robin
authors.initials: R
authors.lastname: Guo
authors.forename: Xiyong
authors.initials: X
authors.lastname: Liu
authors.forename: Stephen N
authors.initials: SN
authors.lastname: Jones
authors.forename: Yun
authors.initials: Y
authors.lastname: Yen
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism* / Q000502:physiology*; D004249:DNA Damage; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000502:physiology*; D006801:Humans; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000502:physiology*; D051736:Proto-Oncogene Proteins c-mdm2 / Q000378:metabolism*; D012264:Ribonucleotide Reductases / Q000737:chemistry / Q000378:metabolism*; D012694:Serine / Q000378:metabolism*; D025521:Tumor Suppressor Proteins / Q000502:physiology*; D014466:Ultraviolet Rays
chemical_list: D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D025521:Tumor Suppressor Proteins; D012694:Serine; C405947:RRM2B protein, human; D012264:Ribonucleotide Reductases; C497206:MDM2 protein, human; D051736:Proto-Oncogene Proteins c-mdm2; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017346:Protein Serine-Threonine Kinases