BS3 intermolecular crosslinking map of SAGA and SLIK (SAGA-like) transcription coactivators

ABSTRACT: The SAGA-like complex SLIK is a modified version of the Spt-Ada-Gcn5-Acetyltransferase (SAGA) complex. SLIK is formed through C-terminal truncation of the Spt7 SAGA subunit, causing loss of Spt8 that interacts with the TATA-binding protein. SLIK and SAGA are both coactivators of RNA polymerase II transcription in yeast. In addition, both SAGA and SLIK perform chromatin modifications and the two complexes have been speculated to uniquely contribute to transcription regulation. To test the respective contribution of SAGA vs. SLIK in transcription regulation, we assayed the chromatin modifying functions of SAGA vs. SLIK, revealing identical kinetics on minimal substrates in vitro. Furthermore, we determined a low-resolution cryo-EM structure of SLIK, revealing a modular architecture identical to SAGA. Finally, we performed a comprehensive study of DNA-binding properties of both coactivators. Purified SAGA and SLIK both associate with ssDNA and dsDNA with high affinity (KD = 10-17 nM) and the binding is sequence-independent. In conclusion, our study shows that the cleavage of Spt7 and the absence of Spt8 subunit in SLIK neither drive any major conformational differences in its structure compared to SAGA, nor significantly affect HAT, DUB or DNA binding activities in vitro.

INSTRUMENT(S): Orbitrap Fusion, Q Exactive HF

ORGANISM(S): Saccharomyces Cerevisiae (baker's Yeast)

SUBMITTER: Ralf Schittenhelm  

LAB HEAD: Marion Boudes

PROVIDER: PXD024640 | Pride | 2021-04-19

REPOSITORIES: Pride