Crosstalk between sumoylation and acetylation regulates p53-dependent chromatin transcription and DNA binding

Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, TX 75390-8807, USA.
The EMBO Journal (Impact Factor: 10.43). 05/2009; 28(9):1246-59. DOI: 10.1038/emboj.2009.83
Source: PubMed


Covalent modification by small ubiquitin-related modifiers (SUMO) regulates p53 transcription activity through an undefined mechanism. Using reconstituted sumoylation components, we purified SUMO-1-conjugated p53 (Su-p53) to near homogeneity. Su-p53 exists in solution as a tetramer and interacts with p300 histone acetyltransferase as efficiently as the unmodified protein. Nevertheless, it fails to activate p53-dependent chromatin transcription because of its inability to bind DNA. With sequential modification assays, we found that sumoylation of p53 at K386 blocks subsequent acetylation by p300, whereas p300-acetylated p53 remains permissive for ensuing sumoylation at K386 and alleviates sumoylation-inhibited DNA binding. While preventing the free form of p53 from accessing its cognate sites, sumoylation fails to disengage prebound p53 from DNA. The sumoylation-deficient K386R protein, when expressed in p53-null cells, exhibits higher transcription activity and binds better to the endogenous p21 gene compared with the wild-type protein. These studies unravel a molecular mechanism underlying sumoylation-regulated p53 function and further uncover a new role of acetylation in antagonizing the inhibitory effect of sumoylation on p53 binding to DNA.

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    • "In vitro, in-cell, and in vivo SUMO assay For the in vitro SUMO assay, all SUMO components were highly purified as previously described (Wu & Chiang, 2009). Flag-FXR was expressed in COS-1 cells and isolated by binding to M2 agarose. "
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    • "Recently, Wu et al demonstrated that sumoylated p53 failed to undergo acetylation, even though the interaction with p300 was still preserved. This suggests that sumoylation of K386 prevents the subsequent acetylation of C-terminal lysines in p53, possibly contributing to a loss of DNA-binding activity of p53, and thus attenuating p53 transcriptional activity [83]. "
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    • "The SUMO E3-ligases PIASs have been mainly implicated in the regulation of innate immunity through epigenetic mechanisms (Liu et al., 2004, 2010; Shuai and Liu, 2005; Rytinki et al., 2009). Moreover, it has been suggested that PIAS1 may regulate oncogenic networks through its ability to inhibit tumor suppressors such as p53, BRCA1, and STAT1 (Schmidt and Muller, 2002; Galanty et al., 2009; Wu and Chiang, 2009). Therefore, our work reveled a novel function of PIAS1. "
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