Nuclear condensates of p300 formed though the structured catalytic core can act as a storage pool of p300 with reduced HAT activity

Yi Zhang,Christopher C Ebmeier,Yucong Yu,Xiaojun Ren,Daniel Panne,Hongwen Xuan,Thomas Lee,Xiaobing Shi,Jiuyang Liu,Mohamad Zandian,Tatiana G Kutateladze,Kyle Brown,Ziad Ibrahim,Steven Ingersoll

doi:10.1038/s41467-021-24950-8

Abstract

The transcriptional co-activator and acetyltransferase p300 is required for fundamental cellular processes, including differentiation and growth. Here, we report that p300 forms phase separated condensates in the cell nucleus. The phase separation ability of p300 is regulated by autoacetylation and relies on its catalytic core components, including the histone acetyltransferase (HAT) domain, the autoinhibition loop, and bromodomain. p300 condensates sequester chromatin components, such as histone H3 tail and DNA, and are amplified through binding of p300 to the nucleosome. The catalytic HAT activity of p300 is decreased due to occlusion of the active site in the phase separated droplets, a large portion of which co-localizes with chromatin regions enriched in H3K27me3. Our findings suggest a model in which p300 condensates can act as a storage pool of the protein with reduced HAT activity, allowing p300 to be compartmentalized and concentrated at poised or repressed chromatin regions.

Highlights

The transcriptional co-activator and acetyltransferase p300 is required for fundamental cellular processes, including differentiation and growth
Located in the middle of the protein, the histone acetyltransferase (HAT) domain is surrounded by BD, a RING finger, and a plant homeodomain finger (PHD) from one side and the ZZ domain from another side that together comprise the catalytic core of p300 (Fig. 1a)
The results described above may suggest that DNA and the HAT domain compete for the same hypoacetylated autoinhibitory loop (AIL), which could lead to a decrease in phase separation ability of p300BRPHZ

Summary

Introduction

The transcriptional co-activator and acetyltransferase p300 is required for fundamental cellular processes, including differentiation and growth. Adding acetyl-CoA to a SIRT2-treated p300BRPHZ/PEG suspension led to a decrease in the cloudiness of the sample within 1 min (Fig. 3b), and liquid droplets were no longer visible under the microscope (Fig. 3c, d, and Supplementary Fig. 3a), indicating a disruption of LLPS due to the HAT reaction.

Results

Conclusion