The SAGA (Spt-Ada-Gcn5-acetyltransferase) complex performs multiple functions in transcription activation including deubiquitinating histone H2B, which is mediated by a subcomplex called the deubiquitinating module (DUBm). The yeast DUBm comprises a catalytic subunit, Ubp8, and three additional subunits, Sgf11, Sus1 and Sgf73, all of which are required for DUBm activity. A portion of the non-globular Sgf73 subunit lies between the Ubp8 catalytic domain and the zinc finger (ZnF)-UBP domain and has been proposed to contribute to deubiquitinating activity by maintaining the catalytic domain in an active conformation. Sgf73 contributes to maintaining both the organization and ubiquitin-binding conformation of Ubp8, thereby contributing to overall DUBm activity. This domain is a Sgf73 fragment in the DUB module. It is a zinc finger (ZnF) domain whose integrity is essential for the incorporation of this subunit into DUBm as well as for the catalytic activity of Ubp8, as either a short deletion or point mutations in Sgf73 zinc-coordinating residues disrupt the association of Sgf73 with the rest of the DUBm [1 -4].

1: Structural basis for assembly and activation of the heterotetrameric SAGA histone H2B deubiquitinase module. Kohler A, Zimmerman E, Schneider M, Hurt E, Zheng N; Cell. 2010;141:606-617. PMID:20434206

2: Structural insights into the assembly and function of the SAGA deubiquitinating module. Samara NL, Datta AB, Berndsen CE, Zhang X, Yao T, Cohen RE, Wolberger C; Science. 2010;328:1025-1029. PMID:20395473

3: A role for intersubunit interactions in maintaining SAGA deubiquitinating module structure and activity. Samara NL, Ringel AE, Wolberger C; Structure. 2012;20:1414-1424. PMID:22771212

4: Uncovering the role of Sgf73 in maintaining SAGA deubiquitinating module structure and activity. Yan M, Wolberger C; J Mol Biol. 2015;427:1765-1778. PMID:25526805