1. GellertM, LipsettMN, DaviesDR (1962) Helix formation by guanylic acid. Proc Natl Acad Sci U S A 48: 2014–2018.
2. SenD, GilbertW (1988) Formation of parallel four-stranded complexes by guanine rich motifs in DNA and its implications for meiosis. Nature 334: 364–366.
3. KimJ, CheongC, MoorePB (1991) Tetramerization of an RNA oligonucleotide containing a GGGG sequence. Nature 351: 331–332.
4. PhanAT, KuryavyiV, PatelDJ (2006) DNA architecture: from G to Z. Curr Opin Struct Biol 16: 288–298.
5. PatelDJ, PhanAT, KuryavyiV (2007) Human telomere, oncogenic promoter and 5′-UTR G-quadruplexes: diverse higher order DNA and RNA targets for cancer therapeutics. Nucleic Acids Res 35: 7429–7455.
6. BesnardE, BabledA, LapassetL, MilhavetO, ParrinelloH, et al. (2012) Unraveling cell type-specific and reprogrammable human replication origin signatures associated with G-quadruplex consensus motifs. Nat Struct Mol Biol 19: 837–844.
7. TuesuwanB, KernJT, ThomasPW, RodriguezM, LiJ, et al. (2008) Simian virus 40 large T-antigen G-quadruplex DNA helicase inhibition by G-quadruplex DNA-interactive agents. Biochemistry 47: 1896–1909.
8. NorseenJ, JohnsonFB, LiebermanPM (2009) Role for G-quadruplex RNA binding by Epstein-Barr virus nuclear antigen 1 in DNA replication and metaphase chromosome attachment. J Virol 83: 10336–10346.
9. ParkinsonGN, LeeMP, NeidleS (2002) Crystal structure of parallel quadruplexes from human telomeric DNA. Nature 417: 876–880.
10. YuHQ, MiyoshiD, SugimotoN (2006) Characterization of structure and stability of long telomeric DNA G-quadruplexes. J Am Chem Soc 128: 15461–15468.
11. HaiderSM, NeidleS, ParkinsonGN (2011) A structural analysis of G-quadruplex/ligand interactions. Biochimie 93: 1239–1251.
12. LukeB, LingnerJ (2009) TERRA: telomeric repeat-containing RNA. EMBO J 28: 2503–2510.
13. MartadinataH, HeddiB, LimKW, PhanAT (2011) Structure of long human telomeric RNA (TERRA): G-quadruplexes formed by four and eight UUAGGG repeats are stable building blocks. Biochemistry 50: 6455–6461.
14. XuY, SuzukiY, ItoK, KomiyamaM (2010) Telomeric repeat-containing RNA structure in living cells. Proc Natl Acad Sci U S A 107: 14579–14584.
15. DengZ, NorseenJ, WiedmerA, RiethmanH, LiebermanPM (2009) TERRA RNA binding to TRF2 facilitates heterochromatin formation and ORC recruitment at telomeres. Mol Cell 35: 403–413.
16. BiffiG, TannahillD, BalasubramanianS (2012) An intramolecular G-quadruplex structure is required for binding of telomeric repeat-containing RNA to the telomeric protein TRF2. J Am Chem Soc 134: 11974–11976.
17. de LangeT (2005) Shelterin: the protein complex that shapes and safeguards human telomeres. Genes Dev 19: 2100–2110.
18. SfeirA, KosiyatrakulST, HockemeyerD, MacRaeSL, KarlsederJ, et al. (2009) Mammalian telomeres resemble fragile sites and require TRF1 for efficient replication. Cell 138: 90–103.
19. SfeirA, de LangeT (2012) Removal of shelterin reveals the telomere end-protection problem. Science 336: 593–597.
20. SmithJS, ChenQ, YatsunykLA, NicoludisJM, GarciaMS, et al. (2011) Rudimentary G-quadruplex-based telomere capping in Saccharomyces cerevisiae. Nat Struct Mol Biol 18: 478–485.
21. SunH, KarowJK, HicksonID, MaizelsN (1998) The Bloom's syndrome helicase unwinds G4 DNA. J Biol Chem 273: 27587–27592.
22. FryM, LoebLA (1999) Human Werner syndrome DNA helicase unwinds tetrahelical structures of the fragile X syndrome repeat sequence d(CGG)n. J Biol Chem 274: 12797–12802.
23. LondonTB, BarberLJ, MosedaleG, KellyGP, BalasubramanianS, et al. (2008) FANCJ is a structure-specific DNA helicase associated with the maintenance of genomic G/C tracts. J Biol Chem 283: 36132–36139.
24. WuY, Shin-YaK, BroshRMJr (2008) FANCJ helicase defective in Fanconi anemia and breast cancer unwinds G-quadruplex DNA to defend genomic stability. Mol Cell Biol 28: 4116–4128.
25. WuY, SommersJA, KhanI, de WinterJP, BroshRMJr (2012) Biochemical characterization of Warsaw breakage syndrome helicase. J Biol Chem 287: 1007–1021.
26. SandersCM (2010) Human Pif1 helicase is a G-quadruplex DNA-binding protein with G-quadruplex DNA-unwinding activity. Biochem J 430: 119–128.
27. DingH, SchertzerM, WuX, GertsensteinM, SeligS, et al. (2004) Regulation of murine telomere length by Rtel: an essential gene encoding a helicase-like protein. Cell 117: 873–886.
28. CrabbeL, VerdunRE, HaggblomCI, KarlsederJ (2004) Defective telomere lagging strand synthesis in cells lacking WRN helicase activity. Science 306: 1951–1953.
29. BarefieldC, KarlsederJ (2012) The BLM helicase contributes to telomere maintenance through processing of late-replicating intermediate structures. Nucleic Acids Res 40: 7358–7367.
30. UringaEJ, YoudsJL, LisaingoK, LansdorpPM, BoultonSJ (2011) RTEL1: an essential helicase for telomere maintenance and the regulation of homologous recombination. Nucleic Acids Res 39: 1647–1655.
31. VannierJB, Pavicic-KaltenbrunnerV, PetalcorinMI, DingH, BoultonSJ (2012) RTEL1 dismantles T loops and counteracts telomeric G4-DNA to maintain telomere integrity. Cell 149: 795–806.
32. KruisselbrinkE, GuryevV, BrouwerK, PontierDB, CuppenE, et al. (2008) Mutagenic capacity of endogenous G4 DNA underlies genome instability in FANCJ-defective C. elegans. Curr Biol 18: 900–905.
33. PiazzaA, BouleJB, LopesJ, MingoK, LargyE, et al. (2010) Genetic instability triggered by G-quadruplex interacting Phen-DC compounds in Saccharomyces cerevisiae. Nucleic Acids Res 38: 4337–4348.
34. LopesJ, PiazzaA, BermejoR, KriegsmanB, ColosioA, et al. (2011) G-quadruplex-induced instability during leading-strand replication. EMBO J 30: 4033–4046.
35. PaeschkeK, CapraJA, ZakianVA (2011) DNA replication through G-quadruplex motifs is promoted by the Saccharomyces cerevisiae Pif1 DNA helicase. Cell 145: 678–691.
36. DavisL, MaizelsN (2011) G4 DNA: at risk in the genome. EMBO J 30: 3878–3879.
37. CahoonLA, SeifertHS (2009) An alternative DNA structure is necessary for pilin antigenic variation in Neisseria gonorrhoeae. Science 325: 764–767.
38. CahoonLA, SeifertHS (2013) Transcription of a cis-acting, noncoding, small RNA is required for pilin antigenic variation in Neisseria gonorrhoeae. PLoS Pathog 9: e1003074 doi:10.1371/journal.ppat.1003074.
39. KuryavyiV, CahoonLA, SeifertHS, PatelDJ (2012) RecA-binding pilE G4 sequence essential for pilin antigenic variation forms monomeric and 5′ end-stacked dimeric parallel G-quadruplexes. Structure 20: 2090–2102.
40. DuquetteML, HandaP, VincentJA, TaylorAF, MaizelsN (2004) Intracellular transcription of G-rich DNAs induces formation of G-loops, novel structures containing G4 DNA. Genes Dev 18: 1618–1629.
41. DuquetteML, PhamP, GoodmanMF, MaizelsN (2005) AID binds to transcription-induced structures in c-MYC that map to regions associated with translocation and hypermutation. Oncogene 24: 5791–5798.
42. DuquetteML, HuberMD, MaizelsN (2007) G-rich proto-oncogenes are targeted for genomic instability in B-cell lymphomas. Cancer Res 67: 2586–2594.
43. MaizelsN (2006) Dynamic roles for G4 DNA in the biology of eukaryotic cells. Nat Struct Mol Biol 13: 1055–1059.
44. LarsonED, DuquetteML, CummingsWJ, StreiffRJ, MaizelsN (2005) MutSalpha binds to and promotes synapsis of transcriptionally activated immunoglobulin switch regions. Curr Biol 15: 470–474.
45. EhratEA, JohnsonBR, WilliamsJD, BorchertGM, LarsonED (2012) G-quadruplex recognition activities of E. Coli MutS. BMC Mol Biol 13: 23.
46. EddyJ, MaizelsN (2006) Gene function correlates with potential for G4 DNA formation in the human genome. Nucleic Acids Res 34: 3887–3896.
47. HuppertJL, BalasubramanianS (2007) G-quadruplexes in promoters throughout the human genome. Nucleic Acids Res 35: 406–413.
48. EddyJ, MaizelsN (2009) Selection for the G4 DNA motif at the 5′ end of human genes. Mol Carcinog 48: 319–325.
49. DuZ, ZhaoY, LiN (2009) Genome-wide colonization of gene regulatory elements by G4 DNA motifs. Nucleic Acids Res 37: 6784–6798.
50. EddyJ, VallurAC, VarmaS, LiuH, ReinholdWC, et al. (2011) G4 motifs correlate with promoter-proximal transcriptional pausing in human genes. Nucleic Acids Res 39: 4975–4983.
51. BalasubramanianS, HurleyLH, NeidleS (2011) Targeting G-quadruplexes in gene promoters: a novel anticancer strategy? Nat Rev Drug Discov 10: 261–275.
52. RaiberEA, KranasterR, LamE, NikanM, BalasubramanianS (2012) A non-canonical DNA structure is a binding motif for the transcription factor SP1 in vitro. Nucleic Acids Res 40: 1499–1508.
53. BugautA, BalasubramanianS (2012) 5′-UTR RNA G-quadruplexes: translation regulation and targeting. Nucleic Acids Res 40: 4727–4741.
54. EddyJ, MaizelsN (2008) Conserved elements with potential to form polymorphic G-quadruplex structures in the first intron of human genes. Nucleic Acids Res 36: 1321–1333.
55. KuryavyiV, PatelDJ (2010) Solution structure of a unique G-quadruplex scaffold adopted by a guanosine-rich human intronic sequence. Structure 18: 73–82.
56. DecorsiereA, CayrelA, VagnerS, MillevoiS (2011) Essential role for the interaction between hnRNP H/F and a G quadruplex in maintaining p53 pre-mRNA 3′-end processing and function during DNA damage. Genes Dev 25: 220–225.
57. Skourti-StathakiK, ProudfootNJ, GromakN (2011) Human senataxin resolves RNA/DNA hybrids formed at transcriptional pause sites to promote Xrn2-dependent termination. Mol Cell 42: 794–805.
58. AguileraA, Garcia-MuseT (2012) R loops: from transcription byproducts to threats to genome stability. Mol Cell 46: 115–124.
59. KimN, Jinks-RobertsonS (2012) Transcription as a source of genome instability. Nat Rev Genet 13: 204–214.
60. GinnoPA, LottPL, ChristensenHC, KorfI, ChedinF (2012) R-loop formation is a distinctive characteristic of unmethylated human CpG island promoters. Mol Cell 45: 814–825.
61. RodriguezR, MillerKM, FormentJV, BradshawCR, NikanM, et al. (2012) Small-molecule-induced DNA damage identifies alternative DNA structures in human genes. Nat Chem Biol 8: 301–310.
62. SantoroMR, BraySM, WarrenST (2012) Molecular mechanisms of Fragile X syndrome: a twenty-year perspective. Annu Rev Pathol 7: 219–245.
63. DeJesus-HernandezM, MackenzieIR, BoeveBF, BoxerAL, BakerM, et al. (2011) Expanded GGGGCC hexanucleotide repeat in noncoding region of C9ORF72 causes chromosome 9p-linked FTD and ALS. Neuron 72: 245–256.
64. FrattaP, MizielinskaS, NicollAJ, ZlohM, FisherEM, et al. (2012) C9orf72 hexanucleotide repeat associated with amyotrophic lateral sclerosis and frontotemporal dementia forms RNA G-quadruplexes. Sci Rep 2: 1016.
65. RentonAE, MajounieE, WaiteA, Simon-SanchezJ, RollinsonS, et al. (2011) A hexanucleotide repeat expansion in C9ORF72 is the cause of chromosome 9p21-linked ALS-FTD. Neuron 72: 257–268.
66. KobayashiH, AbeK, MatsuuraT, IkedaY, HitomiT, et al. (2011) Expansion of intronic GGCCTG hexanucleotide repeat in NOP56 causes SCA36, a type of spinocerebellar ataxia accompanied by motor neuron involvement. Am J Hum Genet 89: 121–130.
67. BorelC, MigliavaccaE, LetourneauA, GagnebinM, BenaF, et al. (2012) Tandem repeat sequence variation as causative cis-eQTLs for protein-coding gene expression variation: the case of CSTB. Hum Mutat 33: 1302–1309.
68. MeadS, WebbTE, CampbellTA, BeckJ, LinehanJM, et al. (2007) Inherited prion disease with 5-OPRI: phenotype modification by repeat length and codon 129. Neurology 69: 730–738.
69. LehmannS, HarrisDA (1996) Two mutant prion proteins expressed in cultured cells acquire biochemical properties reminiscent of the scrapie isoform. Proc Natl Acad Sci U S A 93: 5610–5614.
70. SarkiesP, ReamsC, SimpsonLJ, SaleJE (2010) Epigenetic instability due to defective replication of structured DNA. Mol Cell 40: 703–713.
71. SarkiesP, MuratP, PhillipsLG, PatelKJ, BalasubramanianS, et al. (2011) FANCJ coordinates two pathways that maintain epigenetic stability at G-quadruplex DNA. Nucleic Acids Res 40: 1485–1498.
72. SarkiesP, SaleJE (2011) Propagation of histone marks and epigenetic memory during normal and interrupted DNA replication. Cell Mol Life Sci 69: 697–716.
73. GoldbergAD, BanaszynskiLA, NohKM, LewisPW, ElsaesserSJ, et al. (2010) Distinct factors control histone variant H3.3 localization at specific genomic regions. Cell 140: 678–691.
74. WongLH, McGhieJD, SimM, AndersonMA, AhnS, et al. (2010) ATRX interacts with H3.3 in maintaining telomere structural integrity in pluripotent embryonic stem cells. Genome Res 20: 351–360.
75. LawMJ, LowerKM, VoonHP, HughesJR, GarrickD, et al. (2010) ATR-X syndrome protein targets tandem repeats and influences allele-specific expression in a size-dependent manner. Cell 143: 367–378.
76. MirkinSM (2007) Expandable DNA repeats and human disease. Nature 447: 932–940.
77. WongHM, HuppertJL (2009) Stable G-quadruplexes are found outside nucleosome-bound regions. Mol Biosyst 5: 1713–1719.
78. HalderK, HalderR, ChowdhuryS (2009) Genome-wide analysis predicts DNA structural motifs as nucleosome exclusion signals. Mol Biosyst 5: 1703–1712.
79. HalderR, HalderK, SharmaP, GargG, SenguptaS, et al. (2010) Guanine quadruplex DNA structure restricts methylation of CpG dinucleotides genome-wide. Mol Biosyst 6: 2439–2447.
80. DeS, MichorF (2011) DNA secondary structures and epigenetic determinants of cancer genome evolution. Nat Struct Mol Biol 18: 950–955.
81. BiffiG, TannahillD, McCafferty, SubramanianS (2013) Quantitative visualization of DNA G-quadruplex structures in human cells. Nature Chem 5: 182–186.