Increased and altered DNA binding of human p53 by S and G2/M but not Gl cyclin-dependent kinases

Abstract

Central to the role of p53 in cell regulation are its sequence-specific interactions with genes that control the cell cycle and apoptosis. p53 response elements contain two or more copies of a somewhat promiscuous consensus sequence: 5'-XXXC(A,T)(T,A)GYY-3' (where X is a purine and Y is a pyrimidine) (ref. 3). The sequence-specific DNA-binding region of p53 resides in its central conserved region. Although this region itself is not known to be phosphorylated, the amino and carboxy termini of human p53 contain sites for phosphorylation by several protein kinases. We have examined the role of cyclin-dependent kinase (Cdk) shown previously to phosphorylate human p53 at serine 315 (ref. 5). We report here that p53 is efficiently and selectively phosphorylated by S and G2/M Cdks. Such phosphorylation markedly stimulates sequence-specific DNA binding by p53 and also causes a distinctive conformational change in p53 as revealed by partial protease analysis. Strikingly, Cdk phosphorylation also confers binding-site preference on p53. These data suggest a potential regulatory mechanism of p53 activity.

Effects of bufalin on the proliferation of human lung cancer cells and its molecular mechanisms of action

“…In association with CDK2 complexes, it serves to inhibit kinase activity and block progression through G 1 /S (Pestell et al 1999). When p53 is phosphorylated under UV damage or the treatment with anticancer agents, it upregulates p21 transcription via a p53 responsive element (Wang and Prives 1995). Activation of p53 can lead to either cell cycle arrest and DNA repair or apoptosis (Levine 1997).…”

The post-translational phosphorylation and acetylation modification profile is not the determining factor in targeting endogenous stress-induced p53 to mitochondria

“…12,13 Phosphorylation of Ser 315 and Ser 392 also contributes to regulating the tetramerization state of p53 12 and its ability to bind to cognate sequences in target gene promoters. 14,15 Since post-translational p53 modification is so prominently linked to p53 accumulation and since p53 accumulation is linked to mitochondrial translocation, it has been speculated that a specific phosphorylation/acetylation profile is the determinant mitochondrial targeting signal for p53. To test this idea, we compared the modification patterns of nuclear and mitochondrial p53 protein after genotoxic stress.…”

Conformation-dependent phosphorylation of p53

“…16), cdc2 kinase (17), DNA-dependent protein kinase (18), mitogen-activated protein kinase (19), and protein kinase C (20). Phosphorylation-related function has been demonstrated to affect sequence-specific DNA binding of p53 (9,13,21), transcriptional activities (22,23), simian virus 40 DNA replication (24), growth arrest (25), or to block cellular transformation by dominant oncogenes (26).…”

“…12), which accommodates most of the mutations found so far (3), and the C-terminal portion contains an oligomerization domain and a regulatory domain (amino acids 319-393; ref. 13), the latter of which has been implicated in binding to damaged DNA (14) and in apoptosis (15).…”