Carboxy-terminal region of the yeast heat shock factor contains two domains that make transcription independent of the TFIIH protein kinase.
BACKGROUND
Phosphorylation of the carboxy-terminal domain (CTD) of the largest subunit of RNA polymerase II is implicated in transition from initiation to elongation in the transcription cycle. In yeast cells, Kin28, a subunit of the general transcription factor TFIIH, is responsible for the CTD phosphorylation. Although Kin28 is indispensable for transcription of many genes, its requirement is bypassed in certain genes such as SSA4 or CUP1, whose transcription is activated by the heat shock factor Hsf1.


RESULTS
We show that C-terminal region of Hsf1, which consists of an activation domain AR2 and a regulatory domain CTM, mediates the Kin28-independent transcription. The AR2 domain, when fused to the DNA-binding domain of Gal4 and recruited to the GAL7 gene via the Gal4-binding sequence, is sufficient for activating GAL7 in the absence of Kin28. We have further found that AR2 has an ability to recruit TATA box-binding protein-associated factors (TAFs) to the promoter. Consistently, transcription from promoters occupied naturally or artificially with TAFs is sustained in the absence of Kin28 function.


CONCLUSIONS
These results show that CTM modulates activation function of AR2 in the Hsf1 molecule. We also suggest that recruitment of TAFs to a promoter is involved in the Kin28-independent transcription.
Sakurai
Hiroshi
H
School of Health Sciences, Faculty of Medicine, Kanazawa University, 5-11-80 Kodatsuno, Kanazawa, Ishikawa 920-0942, Japan. sakurai@kenroku.kanazawa-u.ac.jp
Hashikawa
Naoya
N
Imazu
Hiromi
H
Fukasawa
Toshio
T
D002352:Carrier Proteins; D018844:Cyclin-Dependent Kinases / Q000235:genetics / Q000378:metabolism; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D018840:HSP70 Heat-Shock Proteins / Q000096:biosynthesis / Q000235:genetics; D006360:Heat-Shock Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D006358:Hot Temperature; D008668:Metallothionein / Q000096:biosynthesis / Q000235:genetics; D009154:Mutation; D018384:Oxidative Stress; D011401:Promoter Regions, Genetic; D011494:Protein Kinases / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011993:Recombinant Fusion Proteins / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D035381:TATA-Binding Protein Associated Factors / Q000502:physiology; D014157:Transcription Factors / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D015533:Transcriptional Activation
C500769:CUP1-1 protein, S cerevisiae; D002352:Carrier Proteins; D004268:DNA-Binding Proteins; C052130:GAL4 protein, S cerevisiae; C067168:HSF1 protein, S cerevisiae; D018840:HSP70 Heat-Shock Proteins; D006360:Heat-Shock Proteins; D011993:Recombinant Fusion Proteins; C456269:SSA4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035381:TATA-Binding Protein Associated Factors; D014157:Transcription Factors; C007121:copper thionein; D008668:Metallothionein; D011494:Protein Kinases; C060137:carboxy-terminal domain kinase; D018844:Cyclin-Dependent Kinases; C084210:Kin28 protein kinase, S cerevisiae