English
 
Help Privacy Policy Disclaimer
  Advanced SearchBrowse

Item

ITEM ACTIONSEXPORT

Released

Journal Article

Structure of the super-elongation complex subunit AFF4 C-terminal homology domain reveals requirements for AFF homo- and heterodimerization.

MPS-Authors
/persons/resource/persons127020

Cramer,  P.
Department of Molecular Biology, MPI for Biophysical Chemistry, Max Planck Society;

External Resource
No external resources are shared
Fulltext (restricted access)
There are currently no full texts shared for your IP range.
Fulltext (public)

3060625.pdf
(Publisher version), 3MB

Supplementary Material (public)
There is no public supplementary material available
Citation

Chen, Y., & Cramer, P. (2019). Structure of the super-elongation complex subunit AFF4 C-terminal homology domain reveals requirements for AFF homo- and heterodimerization. Journal of Biological Chemistry, 294, 10663-10673. doi:10.1074/jbc.RA119.008577.


Cite as: https://hdl.handle.net/21.11116/0000-0003-B33A-2
Abstract
AF4/FMR2 family member 4 (AFF4) is the scaffold protein of the multi-subunit super-elongation complex (SEC), which plays key roles in the release of RNA polymerase (Pol) II from promoter-proximal pausing and in the transactivation of HIV-1 transcription. AFF4 consists of an intrinsically disordered N-terminal region that interacts with other SEC subunits and a C-terminal homology domain (CHD) that is conserved among AF4/FMR2 family proteins, including AFF1, AFF2, AFF3, and AFF4. Here, we solved the X-ray crystal structure of the CHD in human AFF4 (AFF4-CHD) to 2.2 Å resolution and characterized its biochemical properties. The structure disclosed that AFF4-CHD folds into a novel domain that consists of eight helices and is distantly related to tetratrico peptide repeat (TPR) motifs. Our analyses further revealed that AFF4-CHD mediates the formation of an AFF4 homodimer or an AFF1-AFF4 heterodimer. Results from fluorescence anisotropy experiments suggested that AFF4-CHD interacts with both RNA and DNA in vitro. Furthermore, we identified a surface loop region in AFF4-CHD as a substrate for the P-TEFb kinase cyclin-dependent kinase 9 (CDK9), which triggers release of Pol II from promoter-proximal pausing sites. In conclusion, the AFF-CHD structure and biochemical analyses reported here reveal the molecular basis for the homo- and heterodimerization of AFF proteins and implicate the AFF4-CHD in nucleic acid interactions. The high conservation of the CHD among several other proteins suggests that our results are relevant also for understanding other CHD-containing proteins and their dimerization behavior.