The SAGA (Spt-Ada-Gcn5-Acetyltransferase) transcriptional co-activator is a protein complex that regulates inducible yeast genes by performing multiple functions including acetylating core histones, recruiting the RNA polymerase II preinitiation comp ...
The SAGA (Spt-Ada-Gcn5-Acetyltransferase) transcriptional co-activator is a protein complex that regulates inducible yeast genes by performing multiple functions including acetylating core histones, recruiting the RNA polymerase II preinitiation complex, and deubiquitinating histone H2B. The deubiquitinating activity of SAGA resides in a distinct sub-complex called the deubiquitinating module (DUBm), which consists of four proteins that are conserved across eukaryotes: Ubp8, Sgf11, Sus1 and Sgf73. The DUBm proteins are organized into two lobes around the globular domains of Ubp8 [1]. In SAGA, Sus1 binds to Sgf11 by wrapping around this N-terminal domain of Sgf11, forming a stable dimer [2-4].
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 ...
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].
