InterPro domain: IPR037802

The transcription regulatory histone acetylation complex Spt-Ada-Gcn5 acetyltransferase (SAGA) is involved in RNA polymerase II-dependent transcriptional regulation of approximately 10% of yeast genes. SAGA preferentially acetylates histones H3 and H2B and deubiquitinates histone H2B [ 1 ]. SAGA is known as PCAF in vertebrates and PCAF acetylates nucleosomal histone H3 [ 2 ]. The SAGA complex consists of at least TRA1, CHD1, SPT7, TAF5, ADA3, SGF73, SPT20/ADA5, SPT8, TAF12, TAF6, HFI1/ADA1, UBP8, GCN5, ADA2, SPT3, SGF29, TAF10, TAF9, SGF11 and SUS1, and some of these components are present as two copies. The complex is built up from distinct modules, each of which has a separate function and crosslinks with either other proteins or other modules in the complex [ 3 ].

SAGA-associated factor 29 (SGF29) is a chromatin reader and a component of the transcription regulatory histone acetylation (HAT) complexes SAGA and SLIK [ 4 , 5 ]. In the SAGA complex, SGF29 binds histone H3 that has been methylated at Lys-4 (H3K4me), and preferably binds the trimethylated form (H3K4me3) [ 5 ]. SGF29 also acts as a boundary, preventing the spread of heterochromatin into neighbouring genes [ 6 ].

SLIK (SAGA-like) is a multi-subunit histone acetyltransferase complex that preferentially acetylates histones H3 and H2B and deubiquitinates histone H2B. It is an embellishment of the SAGA complex. The yeast SLIK complex consists of at least TRA1, CHD1, SPT7, CC TAF5, ADA3, SPT20, RTG2, TAF12, TAF6, HFI1, UBP8 (a deubiquitinase), GCN5, ADA2, SPT3, SGF29, TAF10 and TAF9 [ 7 , 7 ].

1. Chd1 chromodomain links histone H3 methylation with SAGA- and SLIK-dependent acetylation. Nature 433, 434-8
2. Histone-like TAFs within the PCAF histone acetylase complex. Cell 94, 35-44
3. Architecture of the Saccharomyces cerevisiae SAGA transcription coactivator complex. EMBO J. 33, 2534-46
4. Expanded lysine acetylation specificity of Gcn5 in native complexes. J. Biol. Chem. 274, 5895-900
5. Sgf29 binds histone H3K4me2/3 and is required for SAGA complex recruitment and histone H3 acetylation. EMBO J. 30, 2829-42
6. The N-terminus and Tudor domains of Sgf29 are important for its heterochromatin boundary formation function. J. Biochem. 155, 159-71
7. The novel SLIK histone acetyltransferase complex functions in the yeast retrograde response pathway. Mol. Cell. Biol. 22, 8774-86