Table 1 |.
DNA helicases and non-B DNA structures
| Helicase | Cellular function | Reported types of non-B DNA processed | Results from helicase deficiency | Ref. |
|---|---|---|---|---|
| Superfamily 1 DNA helicases | ||||
| PIF1 | Unwinding replication barriers, assisting fork progression | G4 | Genetic instability, increased risk of cancer | 289 |
| RRM3 | Unwinding replication barriers, assisting fork progression | G4 | Genetic instability, increased risk of cancer | 290 |
| DNA2 | Telomere maintenance; helicase and G4 nuclease | G4 | Cell senescence, telomere replication defects, genetic instability, increased risk of cancer | 148 |
| Srs2 | Post-replication repair to UV, ionizing radiation or MMS lesions | Cruciform at inverted repeats, hairpin at triplet repeats | UV sensitivity, genetic instability | 291 |
| UvrD | Nucleotide excision repair, mismatch repair, HR | G4, cruciform/Holliday junctions, triplet repeats | UV sensitivity, genetic instability | 292 |
| Rep | DNA replication | G4 | Slow progression of chromosomal replication forks | 293 |
| RecBCD | Helicase and nuclease activities, DSB repair by HR | Cruciform at inverted repeat, hairpin at triplet repeat | Genetic instability | 294 |
| Superfamily 2 DNA helicases | ||||
| RECQ1 (also known as RECQL and RECQL1) | DNA repair, cell cycle and growth, telomere maintenance, transcription | Cruciform/Holliday junctions, very weak on G4 | Genetic instability and increased risk of cancer | 295 |
| RECQ2 (also known as BLM) | DNA replication, immunoglobulin class-switch recombination | G4, triplex H-DNA, direct repeats including triplet repeats | Hereditary Bloom syndrome: primordial dwarfism, genetic instability, increased risk of cancer | 296 |
| Him-6 | BLM homologue in Caenorhabditis elegans | G4 | Genetic instability | 297 |
| RECQ3 (also known as WRN) | Telomere maintenance | G4, hairpin at triplet repeat, triplex H-DNA, Z-DNA | Hereditary Werner syndrome, premature ageing, increased risk of cancer, cell senescence | 298 |
| Sgs1 | Yeast homologue of human BLM and WRN. Forms a complex with Top3 and Rmi1. DNA replication, regulating HR | Cruciform/palindrome, G4, hairpin at triplet repeat | Genetic instability | 291 |
| RECQ4 (also known as RTS) | ATPase activity and single-strand annealing activity, replisome assembly | Holliday junctions, G4 | Hereditary Rothmund–Thomson, RAPADILINO and Baller–Gerold syndromes: skin, hair, skeletal and dental abnormalities, increased risk of cancer | 299 |
| RECQ5 | DNA replication, transcription, repair, suppressing sister chromatid exchanges during HR | G4, an order of magnitude weaker than BLM and WRN | Genetic instability | 300 |
| RTEL1 | Telomere maintenance and HR regulation | G4, hairpin at triplet repeat | Hoyeraal–Hreidarsson syndrome, pulmonary fibrosis and/or bone marrow failure, telomere-related 3 (PFBMFT3), dyskeratosis congenita, autosomal recessive 5 (DKCB5) | 301 |
| DHX36 | RNA and DNA helicase activity, transcription and translation regulation, genetic stability, telomere maintenance | G4 | Genetic instability and increased risk of cancer | 302 |
| DHX9 | DNA replication, transcription, translation, microRNA biogenesis, genetic stability | Triplex H-DNA, Z-DNA | Genetic instability and increased risk of cancer | 303 |
| FANCJ | DNA repair, HR, replication fork progress during replication stress | G4, hairpin at triplet repeat | Hereditary breast and ovarian cancer, Fanconi anaemia, bone marrow failure | 304 |
| Dog-1 | FANCJ homologue in C. elegans | G4 | Genetic instability | 305 |
| XPB/XPD | TFIIH components with functions in nucleotide excision repair | G4, triplex H-DNA | Xeroderma pigmentosum (UV sensitivity, cancer); trichothiodystrophy, Cockayne syndrome (development) | 306 |
| DDX5 | DNA and RNA helicase activity, transcriptional regulation, splicing | G4 | Aberrantly expressed in many tumours | 307 |
| DDX11 (also known as CHLR1), CHL1 in yeast | Chromosome segregation, cell cycle progression, sister chromatid cohesion, putative RNA helicase, translation initiation, splicing | G4, triplex H-DNA | Warsaw breakage syndrome | 308 |
| ATRX | Chromosome alignment and meiotic spindle organization, recombination pathway selection | G4 | α-Thalassaemia with mental retardation | 309 |
DSB, double-strand break; HR, homologous recombination; MMS, methyl methanesulfonate.