Disease relevance of TUP1

• Mutations in either TUP1 or CYC8 eliminate or reduce glucose repression of many repressible genes and induce other phenotypes, including flocculence, failure to sporulate, and sterility of MAT alpha cells [1].
• We raised polyclonal antibodies against TrpE-CYC8 and TrpE-TUP1 fusion proteins expressed in Escherichia coli [2].

High impact information on TUP1

• Computational analysis predicts that proteins capable of recruiting the chromatin regulator Tup1 act to restrict the binding distribution of Rap1 in the presence of glucose [3].
• These data, combined with whole-genome measurements of nucleosome occupancy and Tup1 distribution, provide evidence for a mechanism of dynamic target specification that coordinates the genome-wide distribution of intermediate-affinity DNA sequence motifs with chromatin-mediated regulation of accessibility to those sites [3].
• CRT1 encodes a DNA-binding protein that recruits the general repressors Ssn6 and Tup1 to the promoters of damage-inducible genes [4].
• Here we show that when it is bound upstream of a functional promoter through the LexA DNA-binding domain, Tup1 represses transcription in the absence of Cyc8 [5].
• The alpha 2-Mcm1 complex in turn recruits Ssn6 and Tup1 to the operator, and we believe that these latter two proteins are responsible for the transcriptional repression [6].

Biological context of TUP1

• Repression of a-cell specific gene expression in yeast alpha cells requires MAT alpha 2 and MCM1, as well as two global repressors, SSN6 and TUP1 [7].
• TUP1 is recruited to and represses genes that regulate mating, glucose and oxygen use, stress response, and DNA damage [8].
• Histone deacetylase HDA1, the prototype for the class II mammalian deacetylases, is likely the catalytic subunit of the HDA1-containing complex that is involved in TUP1-specific repression and global deacetylation in yeast [9].
• Deletions of the 3' end of the coding region produced the same mutant phenotypes as did total deletions, suggesting that the C terminus is critical for TUP1 function [1].
• The TUP1 gene was isolated in a screen for genes that regulate mating type (V.L. MacKay, Methods Enzymol. 101:325-343, 1983) [1].

Anatomical context of TUP1

• In a strain deleted for TUP1 that filaments constitutively Tsa1p can be found in the cell wall under all conditions tested, confirming the result that Tsa1p localization to the cell wall is correlated to the morphology of C. albicans [10].
• We identified the H. polymorpha TUP1 gene by functional complementation of the peroxisome degradation deficient mutant pdd2-4 [11].
• Therefore, Efg1p and Tup1p contribute to virulence by regulating hyphal formation and the factors that enable C. albicans to invade and injure endothelial cells [12].
• RESULTS: We found that strains SC5314 and ATCC28366 formed true hyphae on epithelial cells, whereas strain ATCC32077 and the tup1/tup1 mutant formed only pseudohyphae [13].

Associations of TUP1 with chemical compounds

• The TUP1/AER2 protein is known to have significant similarity with the beta subunits of G proteins in the C-terminal half, in two glutamine-rich domains in the N-terminal half, and in a central region rich in serine and threonine residues [14].
• Cells disrupted for the TUP1 or SSN6 genes were constitutively derepressed for the uptake of ferrichrome, ferricrocin or ferrioxamine B, but not for the uptake of triacetylfusarinine C [15].
• The SFL2 gene encodes a 669-amino acid protein which has domains rich in glutamine, as does the SSN6 protein [16].
• Incidentally, iron starvation was noted to induce flavin production and this was misregulated in the absence of TUP1 control [17].
• This derepression occurs in the absence of elevated intracellular levels of serine or threonine and is not observed in cells lacking Rpd3p, Tup1p, or the amino terminus of histone H4 [18].

Physical interactions of TUP1

• It is also shown that TUP1 interacts with HDA1 in vitro [8].
• The Cyc8p/Tup1p complex mediates repression of diverse genes in Saccharomyces cerevisiae and is recruited by DNA binding proteins specific for the different sets of repressed genes [19].
• The formation of nuclease-resistant chromatin does not require the GC boxes, indicating that other cis-acting elements can serve to recruit the Ssn6-Tup1 co-repressor complex to the SUC2 promoter [20].
• In glucose-grown cells, the Mig1 DNA-binding protein recruits the Ssn6-Tup1 corepressor to glucose-repressed promoters in the yeast Saccharomyces cerevisiae [21].
• The interaction is biologically significant, since the deletion of the TUP1 gene as well as the removal of the Tup1p-binding domain from Ppr1p results in an increased expression of the URA3 gene [22].

Regulatory relationships of TUP1

• Furthermore, Tup1 repressed RNR3 and blocked preinitiation complex formation in the Deltaisw2 mutant, even though nucleosome positioning was completely disrupted over the promoter and ORF [23].
• Deletions of SSN6 or TUP1 dramatically de-repressed HEM13 in aerobic cells [24].
• Unexpectedly, we found that LexA-MIG1 activates transcription strongly in an ssn6 mutant and weakly in a tup1 mutant [25].

Other interactions of TUP1

• These data indicate that TUP1 mediates localized histone deacetylation through HDA1 [8].
• These genes constitute a subset of those under Tup1 control, providing further evidence that Nrg1 acts by recruiting Tup1 to target genes [26].
• The chromatin structure downstream of the URS is indistinguishable in Deltaisw2 and Deltatup1 mutants, and the crosslinking of Tup1 and Isw2 to RNR3 is independent of each other, indicating that both complexes are required to maintain repressive chromatin structure [23].
• Ssn6-Tup1 requires the ISW2 complex to position nucleosomes in Saccharomyces cerevisiae [23].
• Repression by SSN6-TUP1 is directed by MIG1, a repressor/activator protein [25].

Analytical, diagnostic and therapeutic context of TUP1

• Sequence analysis of 2.9 kb of DNA including TUP1 revealed only one long open reading frame which predicts a protein of molecular weight 78,221 [1].
• Functional dissection of the global repressor Tup1 in yeast: dominant role of the C-terminal repression domain [27].
• In a similar vein, we find that TUP1, but not SSN6, is required for proper donor selection [28].
• The CYC8 and TUP1 proteins from yeast cells were detected as closely spaced doublets on Western immunoblots of sodium dodecyl sulfate-polyacrylamide gels [2].
• The same DNA microarrays were also used to identify genes whose expression was affected by deletion of the transcriptional co-repressor TUP1 or overexpression of the transcriptional activator YAP1 [29].

References