The mono-ubiquitination of the histone protein H2B (H2Bub1) is a highly conserved histone post-translational modification that plays critical roles in many fundamental processes. In yeast, this modification is catalyzed by the conserved Bre1-Rad6 complex. Bre1 contains a unique N-terminal Rad6 binding domain (RBD), how it interacts with Rad6 and contributes to the H2Bub1 catalysis is unclear. Here, we present crystal structure of the Bre1 RBD-Rad6 complex and structure-guided functional studies. Our structure provides a detailed picture of the interaction between the dimeric Bre1 RBD and a single Rad6 molecule. We further found that the interaction stimulates Rad6's enzymatic activity by allosterically increasing its active site accessibility and likely contribute to the H2Bub1 catalysis through additional mechanisms. In line with these important functions, we found that the interaction is crucial for multiple H2Bub1-regulated processes. Our study provides molecular insights into the H2Bub1 catalysis.
Diffraction data and refined structures of crystal forms 1 and 2 of the KlBre1 RBD-Rad6 complex have been deposited into the protein data bank (www.rcsb.org), with accession codes 7W75 and 7W76, respectively. All data generated or analysed during this study are included in the manuscript and supporting file; source data files are provided for Figures 1-5, figure 1 figure supplement 3 and figure 3 figure supplement 1.
- Song Xiang
- Xuefeng Chen
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
- Xiaobing Shi, Van Andel Institute, United States
© 2023, Shi et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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