ARTICLE Structure of the transcription activator target Tra1 within the chromatin modifying complex SAGA Grigory Sharov 1,2,3,4 , Karine Voltz 1,2,3,4 , Alexandre Durand 5 , Olga Kolesnikova 1,2,3,4 , Gabor Papai 1,2,3,4 , Alexander G. Myasnikov 6 , Annick Dejaegere 1,2,3,4 , Adam Ben Shem 1,2,3,4 & Patrick Schultz 1,2,3,4 The transcription co-activator complex SAGA is recruited to gene promoters by sequence- specific transcriptional activators and by chromatin modifications to promote pre-initiation complex formation. The yeast Tra1 subunit is the major target of acidic activators such as Gal4, VP16, or Gcn4 but little is known about its structural organization. The 430 kDa Tra1 subunit and its human homolog the transformation/transcription domain-associated protein TRRAP are members of the phosphatidyl 3-kinase-related kinase (PIKK) family. Here, we present the cryo-EM structure of the entire SAGA complex where the major target of activator binding, the 430 kDa Tra1 protein, is resolved with an average resolution of 5.7 Å. The high content of alpha-helices in Tra1 enabled tracing of the majority of its main chain. Our results highlight the integration of Tra1 within the major epigenetic regulator SAGA. DOI: 10.1038/s41467-017-01564-7 OPEN 1 Department of Integrated Structural Biology, Institut de Génétique et de Biologie Moléculaire et Cellulaire, 67404 Illkirch, France. 2 Centre National de la Recherche Scientifique, UMR7104, 67404 Illkirch, France. 3 Institut National de la Santé et de la Recherche Médicale, U964, 67404 Illkirch, France. 4 Université de Strasbourg, 67404 Illkirch, France. 5 Research Group ‘Chromosome Organization and Dynamics’, Max Planck Institute of Biochemistry, Am Klopferspitz 18, 82152 Martinsried, Germany. 6 Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA 94158-2517, USA. Correspondence and requests for materials should be addressed to A.B.S. (email: adam@igbmc.fr) or to P.S. (email: patrick.schultz@igbmc.fr) NATURE COMMUNICATIONS | 8: 1556 | DOI: 10.1038/s41467-017-01564-7 | www.nature.com/naturecommunications 1 1234567890