Structural features of human histone acetyltransferase p300 and its complex with p53.

The protein p300 is a multifunctional transcriptional coactivator that plays pivotal role in several cellular functions. Although structures of several domains have been solved in isolation, the structures of full-length protein (p300 FL) or its complexes with transcription activators are completely unknown. Herein, we applied atomic force microscopy to visualize p300 FL. We found that it is almost prolate ellipsoidal in shape, having several bulges. We further identified the functionally significant N-terminal and C-terminal regions, by applying domain-specific antibodies and found that they are located near one end and centre of the molecule, respectively. Importantly, we have visualized the complex between p300 FL and tumor suppressor protein p53. The relevance of these data in understanding dynamics of p300 during acetylation and transcription will be mentioned.