Recombinant Human General transcription and DNA repair factor IIH helicase subunit XPB (ERCC3)

Function

ATP-dependent 3'-5' DNA helicase/translocase (PubMed:17466626, PubMed:27193682, PubMed:33902107, PubMed:8465201, PubMed:8663148). Binds dsDNA rather than ssDNA, unzipping it in a translocase rather than classical helicase activity (PubMed:27193682, PubMed:33902107). Component of the general transcription and DNA repair factor IIH (TFIIH) core complex (PubMed:10024882, PubMed:17466626, PubMed:8157004, PubMed:8465201). When complexed to CDK-activating kinase (CAK), involved in RNA transcription by RNA polymerase II. The ATPase activity of XPB/ERCC3, but not its helicase activity, is required for DNA opening; it may wrap around the damaged DNA wedging it open, causing localized melting that allows XPD/ERCC2 helicase to anchor (PubMed:10024882, PubMed:17466626). In transcription, TFIIH has an essential role in transcription initiation (PubMed:30894545, PubMed:8157004). When the pre-initiation complex (PIC) has been established, TFIIH is required for promoter opening and promoter escape (PubMed:8157004). The ATP-dependent helicase activity of XPB/ERCC3 is required for promoter opening and promoter escape (PubMed:10024882). In transcription pre-initiation complexes induces and propagates a DNA twist to open DNA (PubMed:27193682, PubMed:33902107). Also involved in transcription-coupled nucleotide excision repair (NER) of damaged DNA (PubMed:17466626, PubMed:2111438, PubMed:8157004). In NER, TFIIH acts by opening DNA around the lesion to allow the excision of the damaged oligonucleotide and its replacement by a new DNA fragment. The structure of the TFIIH transcription complex differs from the NER-TFIIH complex; large movements by XPD/ERCC2 and XPB/ERCC3 are stabilized by XPA (PubMed:31253769, PubMed:33902107). XPA retains XPB/ERCC3 at the 5' end of a DNA bubble (mimicking DNA damage) (PubMed:31253769)

Subcellular Location

Nucleus

Disease Association

Xeroderma pigmentosum complementation group B (XP-B) : An autosomal recessive pigmentary skin disorder characterized by solar hypersensitivity of the skin, high predisposition for developing cancers on areas exposed to sunlight and, in some cases, neurological abnormalities. The skin develops marked freckling and other pigmentation abnormalities. Some XP-B patients present features of Cockayne syndrome, including cachectic dwarfism, pigmentary retinopathy, ataxia, decreased nerve conduction velocities. The phenotype combining xeroderma pigmentosum and Cockayne syndrome traits is referred to as XP-CS complex. [The disease is caused by variants affecting the gene represented in this entry] | Trichothiodystrophy 2, photosensitive (TTD2) : A form of trichothiodystrophy, an autosomal recessive disease characterized by sulfur-deficient brittle hair and multisystem variable abnormalities. The spectrum of clinical features varies from mild disease with only hair involvement to severe disease with cutaneous, neurologic and profound developmental defects. Ichthyosis, intellectual and developmental disabilities, decreased fertility, abnormal characteristics at birth, ocular abnormalities, short stature, and infections are common manifestations. There are both photosensitive and non-photosensitive forms of the disorder. [The disease is caused by variants affecting the gene represented in this entry]

Subunit

(Microbial infection) Interacts with Epstein-Barr virus EBNA2

• Weeda G. et al. Molecular cloning and biological characterization of the human excision repair gene ERCC-3. — Mol. Cell. Biol. (1990)
• Weeda G. et al. A presumed DNA helicase encoded by ERCC-3 is involved in the human repair disorders Xeroderma pigmentosum and Cockayne's syndrome. — Cell (1990)
• Weeda G. et al. Structure and expression of the human XPBC/ERCC-3 gene involved in DNA repair disorders xeroderma pigmentosum and Cockayne's syndrome. — Nucleic Acids Res. (1991)
• PubMed: CI-6QALKN8DBUJQA (OCT-)
• Hillier L.W. et al. Generation and annotation of the DNA sequences of human chromosomes 2 and 4. — Nature (2005)
• Mural R.J. et al. PubMed: CI-5GBDQ6B103N1E (JUL-)
• The status, quality, and expansion of the NIH full-length cDNA project: the Mammalian Gene Collection (MGC). — Genome Res. (2004)
• Schaeffer L. et al. DNA repair helicase: a component of BTF2 (TFIIH) basic transcription factor. — Science (1993)