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Gene Review

HOT1  -  Hot1p

Saccharomyces cerevisiae S288c

Synonyms: High-osmolarity-induced transcription protein 1, YM8010.02, YMR172W
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High impact information on HOT1

  • A DNA sequence (HOT1) from the repeated ribosomal RNA gene cluster of Saccharomyces cerevisiae can stimulate genetic exchange when inserted at novel locations in the yeast genome [1].
  • FOB1 was shown previously to be required for replication fork blocking (RFB) activity at RFB site in rDNA and for recombination hot-spot (HOT1) activity [2].
  • In response to high osmolarity, Hot1 targets Hog1 to specific osmostress-responsive promoters [3].
  • Unexpectedly, recruitment of RNA polymerase (Pol) II complex to target promoters does not depend on the phosphorylation of the Hot1 activator by the MAPK [3].
  • In the ribosomal DNA of Saccharomyces cerevisiae, sequences in the nontranscribed spacer 3' of the 35S ribosomal RNA gene are important to the polar arrest of replication forks at a site called the replication fork barrier (RFB) and also to the cis-acting, mitotic hyperrecombination site called HOT1 [4].

Biological context of HOT1


Associations of HOT1 with chemical compounds


Physical interactions of HOT1

  • Studies on rad1 delta rad52-8 strains show that these mutations interact synergistically in the presence or absence of HOT1, resulting in low levels of recombination [10].

Regulatory relationships of HOT1

  • In contrast, Hot1p has little influence on the osmotic stress induction of CTT1, where Msn1p appears to play a more prominent role [5].
  • Compared to recombinants isolated from control strains that lack HOT1, HOT1-promoted His+ recombinants are more often homozygous for sequences distal to HIS4 [11].
  • The Hot1 transcription factor acts downstream of the MAPK and regulates a subset of Hog1-responsive genes [3].

Other interactions of HOT1

  • The rate of gene replacement but not excisive recombination is stimulated by HOT1 in rad1 delta rad52-8 strains [10].
  • There is also a component of HOT1 activity that is independent of both RAD1 and RAD52 [10].
  • Deletion of SCH9 decreases HOT1 and rDNA recombination but not other mitotic exchange [8].
  • When HOT1 is inserted adjacent to both copies of HIS4, the frequency of His+ recombinants is increased approximately 10-fold [11].
  • Ura- recombinants were increased only 2-fold when HOT1 and URA3 were on opposite homologues [12].

Analytical, diagnostic and therapeutic context of HOT1

  • The recombination-stimulating sequence HOT1 is derived from the ribosomal DNA array of Saccharomyces cerevisiae and corresponds to sequences that promote transcription by RNA polymerase I. When inserted at a chromosomal location outside the ribosomal DNA array, HOT1 stimulates mitotic recombination in the adjacent sequences [13].


  1. Recombination-stimulating sequences in yeast ribosomal DNA correspond to sequences regulating transcription by RNA polymerase I. Voelkel-Meiman, K., Keil, R.L., Roeder, G.S. Cell (1987) [Pubmed]
  2. Expansion and contraction of ribosomal DNA repeats in Saccharomyces cerevisiae: requirement of replication fork blocking (Fob1) protein and the role of RNA polymerase I. Kobayashi, T., Heck, D.J., Nomura, M., Horiuchi, T. Genes Dev. (1998) [Pubmed]
  3. Osmostress-induced transcription by Hot1 depends on a Hog1-mediated recruitment of the RNA Pol II. Alepuz, P.M., de Nadal, E., Zapater, M., Ammerer, G., Posas, F. EMBO J. (2003) [Pubmed]
  4. Ribosomal DNA replication fork barrier and HOT1 recombination hot spot: shared sequences but independent activities. Ward, T.R., Hoang, M.L., Prusty, R., Lau, C.K., Keil, R.L., Fangman, W.L., Brewer, B.J. Mol. Cell. Biol. (2000) [Pubmed]
  5. Osmotic stress-induced gene expression in Saccharomyces cerevisiae requires Msn1p and the novel nuclear factor Hot1p. Rep, M., Reiser, V., Gartner, U., Thevelein, J.M., Hohmann, S., Ammerer, G., Ruis, H. Mol. Cell. Biol. (1999) [Pubmed]
  6. Yeast RNA polymerase I enhancer is dispensable for transcription of the chromosomal rRNA gene and cell growth, and its apparent transcription enhancement from ectopic promoters requires Fob1 protein. Wai, H., Johzuka, K., Vu, L., Eliason, K., Kobayashi, T., Horiuchi, T., Nomura, M. Mol. Cell. Biol. (2001) [Pubmed]
  7. DEG1, encoding the tRNA:pseudouridine synthase Pus3p, impacts HOT1-stimulated recombination in Saccharomyces cerevisiae. Hepfer, C.E., Arnold-Croop, S., Fogell, H., Steudel, K.G., Moon, M., Roff, A., Zaikoski, S., Rickman, A., Komsisky, K., Harbaugh, D.L., Lang, G.I., Keil, R.L. Mol. Genet. Genomics (2005) [Pubmed]
  8. SCH9, a putative protein kinase from Saccharomyces cerevisiae, affects HOT1-stimulated recombination. Prusty, R., Keil, R.L. Mol. Genet. Genomics (2004) [Pubmed]
  9. The transcriptional response of Saccharomyces cerevisiae to osmotic shock. Hot1p and Msn2p/Msn4p are required for the induction of subsets of high osmolarity glycerol pathway-dependent genes. Rep, M., Krantz, M., Thevelein, J.M., Hohmann, S. J. Biol. Chem. (2000) [Pubmed]
  10. Genetic control of RNA polymerase I-stimulated recombination in yeast. Zehfus, B.R., McWilliams, A.D., Lin, Y.H., Hoekstra, M.F., Keil, R.L. Genetics (1990) [Pubmed]
  11. A chromosome containing HOT1 preferentially receives information during mitotic interchromosomal gene conversion. Voelkel-Meiman, K., Roeder, G.S. Genetics (1990) [Pubmed]
  12. Gene conversion tracts stimulated by HOT1-promoted transcription are long and continuous. Voelkel-Meiman, K., Roeder, G.S. Genetics (1990) [Pubmed]
  13. Transcription by RNA polymerase I stimulates mitotic recombination in Saccharomyces cerevisiae. Stewart, S.E., Roeder, G.S. Mol. Cell. Biol. (1989) [Pubmed]
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