Architecture of Saccharomyces cerevisiae SAGA complex

a Coomassie blue-stained SDS–PAGE gel and mass spectrometry analysis of a purified native S. cerevisiae SAGA complex. Subunit names are color-coded with green for HAT, yellow for DUB, blue for SPT (red for Tra1), and purple for TAF. b Overall cryo-EM map of S. cerevisiae SAGA complex in front and back views. c Cryo-EM map for individually refined two lobes of S. cerevisiae SAGA. Dark yellow, lobe A; gray, lobe B. Two wing-like regions, R-right and R-left, were marked with dashed circles. d Domain architecture of S. cerevisiae Tra1. e Overall structure of Tra1 docked in its cryo-EM map. Tra1 was shown as a ribbon in rainbow color from N- to C-terminus. f Alignment of Tra1 in the free state (gray) and in the SAGA complex (color-coded by domains). Green arrows denote the N-terminal half of Ring (Ring-N) and the C-terminal half of Ring (Ring-C). Red dashed circles, R-right contact surfaces. g Low-threshold SAGA map highlighting an elongated R-right region (dark gray) that contacts Tra1. The rainbow-colored Tra1 was docked into the 50%-transparent Tra1 map. Contact surface within Ring and Finger domains is highlighted by red dashed circles. h CXMS analysis of the SAGA complex. The two largest subunits, Tra1 and Spt7, are shown as a spreaded domain architecture. Red and black curved lines indicate inter or intra self-links, respectively. Blue and black straight lines indicate protein–protein cross-links. i Cartoon model of the SAGA assembly. A 2D class average image is shown on the left. The SAGA modules or subunits are color-coded as indicated. j Superimposition of NuA4 and SAGA by aligning the two Tra1 structures (Tra1SAGA, dark yellow; Tra1NuA4, green). The subunits of NuA4 (PDB ID: 5Y81)9 are color-coded as indicated. k Electrostatic surface view of Tra1. Electrostatic potential is expressed as a spectrum ranging from –10 kT/e (red) to？+？10 kT/e (blue). Buried surfaces upon SAGA or NuA4 complex formation are shaded by ovals. Putative transcription factor (TF)-binding site is marked with a blue circle. AID activator interaction domain4. l Working model for TF-facilitated chromatin targeting of SAGA and NuA