Biology:Transcription factor II H

From HandWiki
Short description: Protein complex
general transcription factor IIH, polypeptide 1, 62kDa
Identifiers
SymbolGTF2H1
Alt. symbolsBTF2
NCBI gene2965
HGNC4655
OMIM189972
RefSeqNM_005316
UniProtP32780
Other data
LocusChr. 11 p15.1-p14
general transcription factor IIH, polypeptide 2, 44kDa
Identifiers
SymbolGTF2H2
Alt. symbolsBTF2, TFIIH, BTF2P44, T-BTF2P44
NCBI gene2966
HGNC4656
OMIM601748
RefSeqNM_001515
UniProtQ13888
Other data
LocusChr. 5 q12.2-13.3
general transcription factor IIH, polypeptide 3, 34kDa
Identifiers
SymbolGTF2H3
Alt. symbolsBTF2, TFIIH
NCBI gene2967
HGNC4657
OMIM601750
RefSeqNM_001516
UniProtQ13889
Other data
LocusChr. 12 q24.31

Transcription factor II H (TFIIH) is an important protein complex, having roles in transcription of various protein-coding genes and DNA nucleotide excision repair (NER) pathways. TFIIH first came to light in 1989 when general transcription factor-δ or basic transcription factor 2 was characterized as an indispensable transcription factor in vitro. This factor was also isolated from yeast and finally named TFIIH in 1992.[1][2]

TFIIH consists of ten subunits, 7 of which (ERCC2/XPD, ERCC3/XPB, GTF2H1/p62, GTF2H4/p52, GTF2H2/p44, GTF2H3/p34 and GTF2H5/TTDA) form the core complex. The cyclin-activating kinase-subcomplex (CDK7, MAT1, and cyclin H) is linked to the core via the XPD protein.[3] Two of the subunits, ERCC2/XPD and ERCC3/XPB, have helicase and ATPase activities and help create the transcription bubble. In a test tube, these subunits are only required for transcription if the DNA template is not already denatured or if it is supercoiled.

Two other TFIIH subunits, CDK7 and cyclin H, phosphorylate serine amino acids on the RNA polymerase II C-terminal domain and possibly other proteins involved in the cell cycle. Next to a vital function in transcription initiation, TFIIH is also involved in nucleotide excision repair.

History of TFIIH

Before TFIIH identified it, it had several names. It was isolated in 1989 isolated from rat liver, known by factor transcription delta. When identified from cancer cells it was known that time as Basic transcription factor 2. Also, when isolated from yeast it was termed transcription factor B. Finally, in 1992 known as TFIIH.[4]

Structure of TFIIH

TFIIH is a ten‐subunit complex; seven of these subunits comprise the “core” whereas three comprise the dissociable “CAK” (CDK Activating Kinase) module.[5] The core consists of subunits XPB, XPD, p62, p52, p44, p34 and p8 while CAK is composed of CDK7, cyclin H, and MAT1.[6]

Functions

General function of TFIIH:

  1. Initiation transcription of protein- coding gene.[7]
  2. DNA nucleotide repairing.[7]

(NER)TFIIH is a general transcription factor that acts to recruit RNA Pol II to the promoters of genes.  It functions as a helicase that unwinds DNA.  It also unwinds DNA after a DNA lesion has been recognized by either the global genome repair (GGR) pathway or the transcription-coupled repair (TCR) pathway of NER.[8][9] Purified TFIIH has role in stopping further RNA synthesis by activating the cyclic peptide α-amanitin.

Trichothiodystrophy

Mutation in genes ERCC3 (XPB), ERCC2 (XPD) or GTF2H5 (TTDA) cause trichothiodystrophy, a condition characterized by photosensitivity, ichthyosis, brittle hair and nails, intellectual impairment, decreased fertility and/or short stature.[10]

Disease

Genetic polymorphisms of genes that encode subunits of TFIIH are known to be associated with increased cancer susceptibility in many tissues, e.g.; skin tissue, breast tissue and lung tissue. Mutations in the subunits (such as XPD and XPB) can lead to a variety of diseases, including xeroderma pigmentosum (XP) or XP combined with Cockayne syndrome.[11] In addition to genetic variations, virus-encoded proteins also target TFIIH.[12]

DNA repair

TFIIH participates in nucleotide excision repair (NER) by opening the DNA double helix after damage is initially recognized. NER is a multi-step pathway that removes a wide range of different damages that distort normal base pairing, including bulky chemical damages and UV-induced damages. Individuals with mutational defects in genes specifying protein components that catalyze the NER pathway, including the TFIIH components, often display features of premature aging[10][13] (see DNA damage theory of aging).

Inhibitors

Potent, bioactive natural products like triptolide that inhibit mammalian transcription via inhibition of the XPB subunit of the general transcription factor TFIIH has been recently reported as a glucose conjugate for targeting hypoxic cancer cells with increased glucose transporter expression.[14]

Mechanism of TFIIH repairing DNA damaged sequence

Mechanism of TFIIH repairing DNA damaged sequence

References

  1. ↑ "Factors involved in specific transcription by mammalian RNA polymerase II. Identification and characterization of factor IIH". The Journal of Biological Chemistry 267 (4): 2786–93. February 1992. doi:10.1016/S0021-9258(18)45947-9. PMID 1733973. 
  2. ↑ "Mechanism of ATP-dependent promoter melting by transcription factor IIH". Science 288 (5470): 1418–22. May 2000. doi:10.1126/science.288.5470.1418. PMID 10827951. Bibcode: 2000Sci...288.1418K. 
  3. ↑ "Transcription of eukaryotic protein-coding genes". Annual Review of Genetics 34: 77–137. 2000. doi:10.1146/annurev.genet.34.1.77. PMID 11092823. 
  4. ↑ "The essential and multifunctional TFIIH complex". Protein Science 27 (6): 1018–1037. June 2018. doi:10.1002/pro.3424. PMID 29664212. 
  5. ↑ "Dual role of TFIIH in DNA excision repair and in transcription by RNA polymerase II". Nature 368 (6473): 769–72. April 1994. doi:10.1038/368769a0. PMID 8152490. Bibcode: 1994Natur.368..769D. 
  6. ↑ "Dual role of TFIIH in DNA excision repair and in transcription by RNA polymerase II". Nature 368 (6473): 769–72. April 1994. doi:10.1038/368769a0. PMID 8152490. Bibcode: 1994Natur.368..769D. 
  7. ↑ 7.0 7.1 "TFIIH: when transcription met DNA repair". Nature Reviews. Molecular Cell Biology 13 (6): 343–54. May 2012. doi:10.1038/nrm3350. PMID 22572993. 
  8. ↑ "Rapid switching of TFIIH between RNA polymerase I and II transcription and DNA repair in vivo". Molecular Cell 10 (5): 1163–74. November 2002. doi:10.1016/s1097-2765(02)00709-8. PMID 12453423. 
  9. ↑ "TFIIH is an elongation factor of RNA polymerase I". Nucleic Acids Research 40 (2): 650–9. January 2012. doi:10.1093/nar/gkr746. PMID 21965540. 
  10. ↑ 10.0 10.1 "TTDA: big impact of a small protein". Experimental Cell Research 329 (1): 61–8. November 2014. doi:10.1016/j.yexcr.2014.07.008. PMID 25016283. 
  11. ↑ "Phenotypic heterogeneity in the XPB DNA helicase gene (ERCC3): xeroderma pigmentosum without and with Cockayne syndrome". Human Mutation 27 (11): 1092–103. November 2006. doi:10.1002/humu.20392. PMID 16947863. 
  12. ↑ "TFIIH transcription factor, a target for the Rift Valley hemorrhagic fever virus". Cell 116 (4): 541–50. February 2004. doi:10.1016/s0092-8674(04)00132-1. PMID 14980221. 
  13. ↑ "Genome Instability in Development and Aging: Insights from Nucleotide Excision Repair in Humans, Mice, and Worms". Biomolecules 5 (3): 1855–69. August 2015. doi:10.3390/biom5031855. PMID 26287260. 
  14. ↑ "A Glucose-Triptolide Conjugate Selectively Targets Cancer Cells under Hypoxia". iScience 23 (9): 101536. 2020. doi:10.1016/j.isci.2020.101536. PMID 33083765. Bibcode: 2020iSci...23j1536D. 

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