Ste12

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About Ste12

Ste12-GFP is localized in the nucleus. Localization is unchanged by pheromone exposure. van Drogen et al. 2001 PMID 11781566

Ste12 binds to DNA with the consensus sequence (A)TGAAACA. Dolan et al. 1989 PMID 2668945

Ste12 binds to a pair of adjacent PREs with 5-10 higher affinity than it binds to a single PRE. Yuan and Fields. 1991 PMID 1944269
- Ste12 appears to have a slight preference for a tail-to-tail arrangement of PREs than a head-to-tail arrangement of PREs.
- It seems likely that Ste12 acts as a dimer when binding a pair of PREs, although the authors did not show that a single Ste12 wasn't responsible for binding both sites.

PRE sequence (5'-ATGAAACA) act cooperatively to promote transcription in a pheromone dependent manner. Hagen et al. 1991 PMID 1903837
- Two or more PRE sequences are required for efficient transcription in response to pheromone.
- PRE sequences can work in reverse orientation as well, but less efficiently. Artificial upstream activating sequences with mixed forward and reverse PREs result in transcription levels between those achieved with all forward PREs and all reverse PREs.

Ste12 forms a complex with Tec1 and regulates transcriptional response during filamentation and invasive growth. Madhani and Fink. 1997 PMID 9036858

Fusion of Ste12 residues 301-335 between the Gal4 DNA binding domain and the Gal4 transcriptional activation domain I (GBD-Ste12(301-335)GADI) results in pheromone dependent transcription of GAL1-lacZ. Pi et al. 1997 PMID 9343403
- Ste12 residues 301-335 are the minimal region of Ste12 that emparts pheromone dependent transcription to this construct.
- The pheromone-dependent transcription is eliminated in fus3Δ kss1Δ and ste5Δ cells.
- Residues 302-317 of Ste12 are highly conserved between Kluyveromyces lactis and Saccharomyces cerevisiae.

Mutation of all serines and threonines to alanines in Ste12(301-335) of the (GBD-Ste12(301-335)GADI) protein did not affect this fusions proteins ability to response to pheromone. Pi et al. 1997 PMID 9343403
- This suggests that phosphorylation by Fus3 or Kss1 in this region of Ste12 is not important for regulation.

Pheromone treatment does not affect the ability of Ste12 from cell extracts to interact with DNA in vitro (gel mobility-shift assay). Song et al. 1991 PMID 2026326

Ste12 appears to act as dimers/multimers to activate gene expression. Olson et al. 2000 PMID 10825185
- Full length Ste12 can interact with various portions of Ste12 fused to the Gal4 DNA binding domain, including Ste12(216-688), Ste12(216-473) and Ste12(474-688) (coimmunoprecipitation). Since non overlapping regions of Ste12 can interact with full-length Ste12, there are presumably mutliple domains responsible for dimerization/multimerization.
- Full-length Ste12 can interact with GST-Ste12(216-500) and GST-Ste12(450-688).
- LexA-Ste12 fusion proteins (LexA-Ste12(356-688) and LexA-Ste12(450-688)) lacking the activation domain (residues 301-335) are by themselves unable to activate expression of a LexA-responsive reporter.
- Coexpression of Ste12(216-688) (but not Ste12(356-688)) with LexA-Ste12(356-688) or LexA-Ste12(450-688)) results in expression of the LexA-responsive reporter.
- This suggests that Ste12 can act as a dimer/multimer, where one monomer supplies the relevant DNA binding domain, and another monomer supplies the activation domain.

Binding of Ste12(1-215) to a PRE is inhibited in vitro by addition of Dig2, but not by Dig1 (data not shown). Olson et al. 2000 PMID 10825185

Mutation or deletion of the N-terminal 20 amino acids of Ste12 results in 30-fold higher FUS1-LacZ expression in the absence of pheromone. Crosby et al. 2000 PMID 11054817
- Fusions between the activating domain of Gal4 and DNA-binding domain of Ste12 (with and without residues 1-20) demonstrate that the deletion of the N-terminal 20 amino acids increases the DNA binding of Ste12.
- Fusions between the DNA-binding domain of Gal4 (which is much stronger than that from Ste12) and the full-length Ste12 (with and without residues 1-20) demonstrate that the deletion of the N-terminal 20 amino acids does not detectably affect the activation activity of Ste12.
- This authors did not show whether this deletion eliminates Dig2/Ste12 binding, decreases Dig2/Ste12 binding affinity , or does not affect Dig2 repression.

All promoters bound by Tec1 (identified by Chromatin immunoprecipitation (ChIP)) also bound Ste12. Zeitlinger et al. 2003 PMID 12732146

Ste12 is sumoylated, and sumoylation is increased in response to pheromone (FLAG tagged Ste12 purified and probed on gel with anti SUMO antibodies). Wang and Dohlman. 2005 PMID 16306045

Expression of a FLAG-SUMO-Ste12 fusion protein increases PRE-LacZ expression in response to pheromone (though PRE-LacZ expression in the absence of pheromone is unchanged). Wang and Dohlman. 2005 PMID 16306045
- FLAG-SUMO-Ste12 cells exhibit slightly increased growth arrest over FLAG-Ste12 cells (as judged by halo assay).
- FLAG-SUMO-Ste12 cells exhibit decreased invasive growth over FLAG-Ste12 cells.
- FLAG-SUMO-Ste12 appears to be expressed at lower levels than FLAG-Ste12, but it's not entirely certain because FLAG-SUMO-Ste12 appears as a series of blurred bands on the gel.

Ste12 required multiple copies of the PRE (pheromone response element) in the UAS of a gene for pheromone induced transcription. Sengupta and Cochran. 1990 PMID 2247085

Ste12 homodimers regulate pheromone-induced transcription of genes that are expressed in both cell types. Ste12 interacts with Mcm1 dimers to regulate pheromone-induced transcription of a-specific genes, and it interacts with Mcm1 dimers and Matα1 to regulate pheromone-induced transcription of α-specific genes. Dohlman and Thorner. 2001 PMID 11395421

Ste12 and Mcm1 bind together (possibly cooperatively) to adjacent sites in the Ste2 upstream activating sequence. Errede and Ammerer. 1989 PMID 2558054

Ste12 interacts with an Mcm1 dimer to bind to the Ste2 upstream activating sequence in vitro. Mueller and Nordheim. 1991 PMID 1756729
- Mcm1 dimers bind to the Ste2 UAS in the absence of Ste12, but Ste12 doesn't interact with the Ste2 UAS in the absence of Mcm1.

Ste12 negatively regulates Pry3 expression by binding the PRY3 promoter region, interfering with full length PRY3 mRNA expression, and inducing expression of a shorter PRY3 transcript. Bickel and Morris. 2006 PMID 16940175

Ste12(Dig1_site, Dig2_site, MAPK_site)

Ste12(Dig1_site, Dig2_site, MAPK_site) Ste12_tot_conc