SPT8/YLR055C Summary Help

Standard Name SPT8
Systematic Name YLR055C
Feature Type ORF, Verified
Description Subunit of the SAGA transcriptional regulatory complex; not present in SAGA-like complex SLIK/SALSA; required for SAGA-mediated inhibition at some promoters (1, 2 and see Summary Paragraph)
Name Description SuPpressor of Ty
Chromosomal Location
ChrXII:253080 to 251272 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: 30 cM
Gene Ontology Annotations All SPT8 GO evidence and references
  View Computational GO annotations for SPT8
Molecular Function
Manually curated
Biological Process
Manually curated
Cellular Component
Manually curated
Targets 38 genes
Regulators 4 genes
Classical genetics
Large-scale survey
617 total interaction(s) for 315 unique genes/features.
Physical Interactions
  • Affinity Capture-MS: 181
  • Affinity Capture-RNA: 3
  • Affinity Capture-Western: 20
  • Biochemical Activity: 4
  • Co-localization: 1
  • Co-purification: 9
  • PCA: 1
  • Reconstituted Complex: 19
  • Two-hybrid: 1

Genetic Interactions
  • Dosage Lethality: 1
  • Negative Genetic: 165
  • Phenotypic Enhancement: 5
  • Positive Genetic: 33
  • Synthetic Growth Defect: 84
  • Synthetic Lethality: 75
  • Synthetic Rescue: 15

Expression Summary
Length (a.a.) 602
Molecular Weight (Da) 66,189
Isoelectric Point (pI) 4.12
Phosphorylation PhosphoGRID | PhosphoPep Database
sequence information
ChrXII:253080 to 251272 | ORF Map | GBrowse
Note: this feature is encoded on the Crick strand.
Genetic position: 30 cM
Last Update Coordinates: 2011-02-03 | Sequence: 1996-07-31
Subfeature details
Most Recent Updates
Coordinates Sequence
CDS 1..1809 253080..251272 2011-02-03 1996-07-31
Retrieve sequences
Analyze Sequence
S288C only
S288C vs. other species
S288C vs. other strains
External Links All Associated Seq | Entrez Gene | Entrez RefSeq Protein | MIPS | Search all NCBI (Entrez) | UniProtKB
Primary SGDIDS000004045

SPT8 encodes a subunit of SAGA, a histone acetyltransferase and transcriptional coactivator complex that regulates transcription of a subset of RNA polymerase II-dependent genes (3, 4, 5). At some SAGA-dependent promoters, Spt8p helps to mediate recruitment of the general transcription machinery and thus positively regulates transcription (6, 7). In addition, Spt8p negatively affects basal expression of some promoters by preventing SAGA interaction with the transcription machinery (8, 9). Spt8p does not appear to have a role in the cell independent of its functions in the SAGA complex (10).

Spt8p, along with Spt3p, form one class of SAGA subunits whose role is to control the TATA box binding protein (TBP)-TATA interaction at the promoter (8, 6, 11, 12). Evidence suggests that the positive and negative functions of Spt8p in transcription are mediated through the general transcription factor TFIIA (9). Photocrosslinking studies of pre-initiation complexes (PICs) indicate that Spt8p is in close proximity with TFIIA and TBP (Spt15p). Spt8p can interact with TBP (9, 3) and appears to compete with TFIIA for binding to TBP. Under conditions of basal transcription, this competition may prevent optimal expression, while under activated conditions, the competition is averted, perhaps through a conformational change in Spt8p or TFIIA that enables them both to bind TBP and stimulate transcription (9).

SPT8 was originally identified in a genetic screen for mutations that suppress Ty or solo Delta insertions in the upstream regions of the HIS4 and LYS2 genes (13). spt8 mutants display phenotypes similar to those of spt3 and spt7 mutants: suppression of Ty and Delta insertion mutations, failure to sporulate, and altered initiation of Ty transcription (such that the startpoint is ~800 bases downstream of the normal site) (13). Null mutations in SPT8 are suppressed by some spt3 mutations (11), a result consistent with functional overlap of Spt8p and Spt3p in SAGA. Cloning of SPT8 revealed that it encodes a protein that is very acidic, particularly in the N-terminal region where 49 of the first 76 amino acids are aspartic or glutamic acid. Spt8p also contains a single WD40 repeat, a motif found in a number of proteins including the beta subunits of heterotrimeric G proteins (11).

The association of Spt8p with SAGA is dependent on its interaction with a carboxy terminal region of Spt7p (10). Cells contain an altered form of SAGA, referred to as SLIK (SAGA-like) or SALSA (SAGA altered, Spt8 absent), which is also involved in transcription activation (14, 1). This complex lacks Spt8p and contains a truncated form of Spt7p.

Characterized subunits of the SAGA complex include: Hfi1p, Ada2p, Ngg1p, Spt20p, Gcn5p, Spt3p, Spt7p, Spt8p, Tra1p, Taf5p, Taf6p, Taf9p, Taf10p, Taf12p, Ubp8p, and Sgf11p (15, 16; reviewed in 1).

Last updated: 2006-06-30 Contact SGD

References cited on this page View Complete Literature Guide for SPT8
1) Sterner DE, et al.  (2002) SALSA, a variant of yeast SAGA, contains truncated Spt7, which correlates with activated transcription. Proc Natl Acad Sci U S A 99(18):11622-7
2) Bhaumik SR and Green MR  (2002) Differential requirement of SAGA components for recruitment of TATA-box-binding protein to promoters in vivo. Mol Cell Biol 22(21):7365-71
3) Sterner DE, et al.  (1999) Functional organization of the yeast SAGA complex: distinct components involved in structural integrity, nucleosome acetylation, and TATA-binding protein interaction. Mol Cell Biol 19(1):86-98
4) Roberts SM and Winston F  (1997) Essential functional interactions of SAGA, a Saccharomyces cerevisiae complex of Spt, Ada, and Gcn5 proteins, with the Snf/Swi and Srb/mediator complexes. Genetics 147(2):451-65
5) Grant PA, et al.  (1997) Yeast Gcn5 functions in two multisubunit complexes to acetylate nucleosomal histones: characterization of an Ada complex and the SAGA (Spt/Ada) complex. Genes Dev 11(13):1640-50
6) Bhaumik SR and Green MR  (2001) SAGA is an essential in vivo target of the yeast acidic activator Gal4p. Genes Dev 15(15):1935-45
7) Larschan E and Winston F  (2001) The S. cerevisiae SAGA complex functions in vivo as a coactivator for transcriptional activation by Gal4. Genes Dev 15(15):1946-56
8) Belotserkovskaya R, et al.  (2000) Inhibition of TATA-binding protein function by SAGA subunits Spt3 and Spt8 at Gcn4-activated promoters. Mol Cell Biol 20(2):634-47
9) Warfield L, et al.  (2004) Positive and negative functions of the SAGA complex mediated through interaction of Spt8 with TBP and the N-terminal domain of TFIIA. Genes Dev 18(9):1022-34
10) Wu PY and Winston F  (2002) Analysis of Spt7 function in the Saccharomyces cerevisiae SAGA coactivator complex. Mol Cell Biol 22(15):5367-79
11) Eisenmann DM, et al.  (1994) The Saccharomyces cerevisiae SPT8 gene encodes a very acidic protein that is functionally related to SPT3 and TATA-binding protein. Genetics 137(3):647-57
12) Dudley AM, et al.  (1999) The Spt components of SAGA facilitate TBP binding to a promoter at a post-activator-binding step in vivo. Genes Dev 13(22):2940-5
13) Winston F, et al.  (1987) Three genes are required for trans-activation of Ty transcription in yeast. Genetics 115(4):649-56
14) Pray-Grant MG, et al.  (2002) The novel SLIK histone acetyltransferase complex functions in the yeast retrograde response pathway. Mol Cell Biol 22(24):8774-86
15) Henry KW, et al.  (2003) Transcriptional activation via sequential histone H2B ubiquitylation and deubiquitylation, mediated by SAGA-associated Ubp8. Genes Dev 17(21):2648-63
16) Lee KK, et al.  (2005) The deubiquitylation activity of Ubp8 is dependent upon Sgf11 and its association with the SAGA complex. Mol Cell Biol 25(3):1173-82