The effects of manipulating levels of replication initiation factors on origin firing efficiency in yeast

English version

Autoři: Kelsey L. Lynch ^aff001; Gina M. Alvino ^aff002; Elizabeth X. Kwan ^aff002; Bonita J. Brewer ^aff001; M. K. Raghuraman ^aff002
Působiště autorů: Molecular and Cellular Biology Program, University of Washington, Seattle, Washington, United States of America ^aff001; Department of Genome Sciences, University of Washington, Seattle, Washington, United States of America ^aff002
Vyšlo v časopise: The effects of manipulating levels of replication initiation factors on origin firing efficiency in yeast. PLoS Genet 15(10): e32767. doi:10.1371/journal.pgen.1008430
Kategorie: Research Article
doi: https://doi.org/10.1371/journal.pgen.1008430

Souhrn

Chromosome replication in Saccharomyces cerevisiae is initiated from ~300 origins that are regulated by DNA sequence and by the limited abundance of six trans-acting initiation proteins (Sld2, Sld3, Dpb11, Dbf4, Sld7 and Cdc45). We set out to determine how the levels of individual factors contribute to time of origin activation and/or origin efficiency using induced depletion of single factors and overexpression of sets of multiple factors. Depletion of Sld2 or Sld3 slows growth and S phase progression, decreases origin efficiency across the genome and impairs viability as a result of incomplete replication of the rDNA. We find that the most efficient early origins are relatively unaffected by depletion of either Sld2 or Sld3. However, Sld3 levels, and to a lesser extent Sld2 levels, are critical for firing of the less efficient early origins. Overexpression of Sld3 simultaneously with Sld2, Dpb11 and Dbf4 preserves the relative efficiency of origins. Only when Cdc45 and Sld7 are also overexpressed is origin efficiency equalized between early- and late-firing origins. Our data support a model in which Sld3 together with Cdc45 (and/or Sld7) is responsible for the differential efficiencies of origins across the yeast genome.

Klíčová slova:

Auxins – Cell cycle and cell division – DNA replication – Flow cytometry – Gel electrophoresis – Hyperexpression techniques – Saccharomyces cerevisiae – Synthesis phase

Zdroje

1. Cairns J. Autoradiography of HeLa cell DNA. J Mol Biol. 1966;15(1):372–3. doi: 10.1016/s0022-2836(66)80233-4 5912048.

2. Prioleau MN, MacAlpine DM. DNA replication origins-where do we begin? Genes Dev. 2016;30(15):1683–97. doi: 10.1101/gad.285114.116 27542827; PubMed Central PMCID: PMC5002974.

3. Lima-de-Faria A, Jaworska H. Late DNA synthesis in heterochromatin. Nature. 1968;217:138–42. doi: 10.1038/217138a0 18300398

4. Taylor JH. Asynchronous duplication of chromosomes incultured cells of Chinese hamster. J Biophysic Biochem Cytol. 1960;7:455–63.

5. Ferguson BM, Brewer BJ, Reynolds AE, Fangman WL. A yeast origin of replication is activated late in S phase. Cell. 1991;65(3):507–15. doi: 10.1016/0092-8674(91)90468-e 2018976

6. Raghuraman MK, Winzeler EA, Collingwood D, Hunt S, Wodicka L, Conway A, et al. Replication dynamics of the yeast genome. Science. 2001;294(5540):115–21. doi: 10.1126/science.294.5540.115 11588253

7. Brewer BJ, Fangman WL. A replication fork barrier at the 3' end of yeast ribosomal RNA genes. Cell. 1988;55(4):637–43. doi: 10.1016/0092-8674(88)90222-x 3052854

8. Newlon CS, Lipchitz LR, Collins I, Deshpande A, Devenish RJ, Green RP, et al. Analysis of a circular derivative of Saccharomyces cerevisiae chromosome III: a physical map and identification and location of ARS elements. Genetics. 1991;129(2):343–57. 1683846; PubMed Central PMCID: PMC1204628.

9. Rhind N, Gilbert DM. DNA replication timing. Cold Spring Harbor perspectives in biology. 2013;5(8):a010132. doi: 10.1101/cshperspect.a010132 23838440; PubMed Central PMCID: PMC3721284.

10. McCune HJ, Danielson LS, Alvino GM, Collingwood D, Delrow JJ, Fangman WL, et al. The Temporal Program of Chromosome Replication: Genomewide Replication in clb5Δ Saccharomyces cerevisiae. Genetics. 2008;180(4):1833–47. doi: 10.1534/genetics.108.094359 18832352.

11. Koren A, Handsaker RE, Kamitaki N, Karlic R, Ghosh S, Polak P, et al. Genetic variation in human DNA replication timing. Cell. 2014;159(5):1015–26. doi: 10.1016/j.cell.2014.10.025 25416942; PubMed Central PMCID: PMC4359889.

12. Bell SP, Labib K. Chromosome Duplication in Saccharomyces cerevisiae. Genetics. 2016;203(3):1027–67. doi: 10.1534/genetics.115.186452 27384026; PubMed Central PMCID: PMC4937469.

13. Bell SP, Stillman B. ATP-dependent recognition of eukaryotic origins of DNA replication by a multiprotein complex. Nature. 1992;357:128–34. doi: 10.1038/357128a0 1579162

14. Diffley JF, Cocker JH. Protein-DNA interactions at a yeast replication origin. Nature. 1992;357(6374):169–72. doi: 10.1038/357169a0 1579168

15. Diffley JF, Cocker JH, Dowell SJ, Rowley A. Two steps in the assembly of complexes at yeast replication origins in vivo. Cell. 1994;78(2):303–16. doi: 10.1016/0092-8674(94)90299-2 8044842

16. Sun J, Evrin C, Samel SA, Fernandez-Cid A, Riera A, Kawakami H, et al. Cryo-EM structure of a helicase loading intermediate containing ORC-Cdc6-Cdt1-MCM2-7 bound to DNA. Nat Struct Mol Biol. 2013;20(8):944–51. doi: 10.1038/nsmb.2629 23851460; PubMed Central PMCID: PMC3735830.

17. Douglas ME, Ali FA, Costa A, Diffley JFX. The mechanism of eukaryotic CMG helicase activation. Nature. 2018;555(7695):265–8. doi: 10.1038/nature25787 29489749.

18. Ilves I, Petojevic T, Pesavento JJ, Botchan MR. Activation of the MCM2-7 helicase by association with Cdc45 and GINS proteins. Mol Cell. 2010;37(2):247–58. doi: 10.1016/j.molcel.2009.12.030 20122406; PubMed Central PMCID: PMC6396293.

19. Bousset K, Diffley JF. The Cdc7 protein kinase is required for origin firing during S phase. Genes Dev. 1998;12(4):480–90. doi: 10.1101/gad.12.4.480 9472017

20. Donaldson AD, Fangman WL, Brewer BJ. Cdc7 is required throughout the yeast S phase to activate replication origins. Genes Dev. 1998;12(4):491–501. doi: 10.1101/gad.12.4.491 9472018

21. Donaldson AD, Raghuraman MK, Friedman KL, Cross FR, Brewer BJ, Fangman WL. CLB5-dependent activation of late replication origins in S. cerevisiae. Mol Cell. 1998;2(2):173–82. doi: 10.1016/s1097-2765(00)80127-6 9734354

22. Jackson AL, Pahl PM, Harrison K, Rosamond J, Sclafani RA. Cell cycle regulation of the yeast Cdc7 protein kinase by association with the Dbf4 protein. Mol Cell Biol. 1993;13(5):2899–908. doi: 10.1128/mcb.13.5.2899 8474449

23. Labib K. How do Cdc7 and cyclin-dependent kinases trigger the initiation of chromosome replication in eukaryotic cells? Genes Dev. 2010;24(12):1208–19. doi: 10.1101/gad.1933010 20551170; PubMed Central PMCID: PMC2885657.

24. Bloom J, Cross FR. Multiple levels of cyclin specificity in cell-cycle control. Nat Rev Mol Cell Biol. 2007;8(2):149–60. doi: 10.1038/nrm2105 17245415.

25. Natsume T, Muller CA, Katou Y, Retkute R, Gierlinski M, Araki H, et al. Kinetochores coordinate pericentromeric cohesion and early DNA replication by Cdc7-Dbf4 kinase recruitment. Mol Cell. 2013;50(5):661–74. doi: 10.1016/j.molcel.2013.05.011 23746350; PubMed Central PMCID: PMC3679449.

26. Fang D, Lengronne A, Shi D, Forey R, Skrzypczak M, Ginalski K, et al. Dbf4 recruitment by forkhead transcription factors defines an upstream rate-limiting step in determining origin firing timing. Genes Dev. 2017;31(23–24):2405–15. doi: 10.1101/gad.306571.117 29330352; PubMed Central PMCID: PMC5795786.

27. Knott SR, Peace JM, Ostrow AZ, Gan Y, Rex AE, Viggiani CJ, et al. Forkhead transcription factors establish origin timing and long-range clustering in S. cerevisiae. Cell. 2012;148(1–2):99–111. doi: 10.1016/j.cell.2011.12.012 22265405; PubMed Central PMCID: PMC3266545.

28. Pohl TJ, Brewer BJ, Raghuraman MK. Functional centromeres determine the activation time of pericentric origins of DNA replication in Saccharomyces cerevisiae. PLoS Genet. 2012;8(5):e1002677. doi: 10.1371/journal.pgen.1002677 22589733; PubMed Central PMCID: PMC3349730.

29. Vogelauer M, Rubbi L, Lucas I, Brewer BJ, Grunstein M. Histone acetylation regulates the time of replication origin firing. Mol Cell. 2002;10(5):1223–33. doi: 10.1016/s1097-2765(02)00702-5 12453428.

30. Mantiero D, Mackenzie A, Donaldson A, Zegerman P. Limiting replication initiation factors execute the temporal programme of origin firing in budding yeast. EMBO J. 2011;30(23):4805–14. doi: 10.1038/emboj.2011.404 22081107; PubMed Central PMCID: PMC3243606.

31. McGuffee SR, Smith DJ, Whitehouse I. Quantitative, genome-wide analysis of eukaryotic replication initiation and termination. Mol Cell. 2013;50(1):123–35. doi: 10.1016/j.molcel.2013.03.004 23562327; PubMed Central PMCID: PMC3628276.

32. Tanaka S, Nakato R, Katou Y, Shirahige K, Araki H. Origin association of Sld3, Sld7, and Cdc45 proteins is a key step for determination of origin-firing timing. Curr Biol. 2011;21(24):2055–63. doi: 10.1016/j.cub.2011.11.038 22169533.

33. Deegan TD, Yeeles JT, Diffley JF. Phosphopeptide binding by Sld3 links Dbf4-dependent kinase to MCM replicative helicase activation. EMBO J. 2016;35(9):961–73. doi: 10.15252/embj.201593552 26912723; PubMed Central PMCID: PMC4864760.

34. Muramatsu S, Hirai K, Tak YS, Kamimura Y, Araki H. CDK-dependent complex formation between replication proteins Dpb11, Sld2, Pol epsilon, and GINS in budding yeast. Genes Dev. 2010;24(6):602–12. doi: 10.1101/gad.1883410 20231317; PubMed Central PMCID: PMC2841337.

35. Tanaka S, Umemori T, Hirai K, Muramatsu S, Kamimura Y, Araki H. CDK-dependent phosphorylation of Sld2 and Sld3 initiates DNA replication in budding yeast. Nature. 2007;445(7125):328–32. doi: 10.1038/nature05465 17167415.

36. Zegerman P, Diffley JF. Phosphorylation of Sld2 and Sld3 by cyclin-dependent kinases promotes DNA replication in budding yeast. Nature. 2007;445(7125):281–5. doi: 10.1038/nature05432 17167417.

37. Tanaka T, Umemori T, Endo S, Muramatsu S, Kanemaki M, Kamimura Y, et al. Sld7, an Sld3-associated protein required for efficient chromosomal DNA replication in budding yeast. EMBO J. 2011;30(10):2019–30. doi: 10.1038/emboj.2011.115 21487389; PubMed Central PMCID: PMC3098486.

38. Collart C, Allen GE, Bradshaw CR, Smith JC, Zegerman P. Titration of four replication factors is essential for the Xenopus laevis midblastula transition. Science. 2013;341(6148):893–6. doi: 10.1126/science.1241530 23907533; PubMed Central PMCID: PMC3898016.

39. Farrell JA O'Farrell PH. From egg to gastrula: how the cell cycle is remodeled during the Drosophila mid-blastula transition. Annu Rev Genet. 2014;48:269–94. doi: 10.1146/annurev-genet-111212-133531 25195504; PubMed Central PMCID: PMC4484755.

40. Langley AR, Smith JC, Stemple DL, Harvey SA. New insights into the maternal to zygotic transition. Development. 2014;141(20):3834–41. doi: 10.1242/dev.102368 25294937.

41. Kamimura Y, Tak YS, Sugino A, Araki H. Sld3, which interacts with Cdc45 (Sld4), functions for chromosomal DNA replication in Saccharomyces cerevisiae. Embo J. 2001;20(8):2097–107. doi: 10.1093/emboj/20.8.2097 11296242

42. Sheu YJ, Stillman B. The Dbf4-Cdc7 kinase promotes S phase by alleviating an inhibitory activity in Mcm4. Nature. 2010;463(7277):113–7. doi: 10.1038/nature08647 20054399; PubMed Central PMCID: PMC2805463.

43. Kubota T, Nishimura K, Kanemaki MT, Donaldson AD. The Elg1 replication factor C-like complex functions in PCNA unloading during DNA replication. Mol Cell. 2013;50(2):273–80. doi: 10.1016/j.molcel.2013.02.012 23499004.

44. Nishimura K, Fukagawa T, Takisawa H, Kakimoto T, Kanemaki M. An auxin-based degron system for the rapid depletion of proteins in nonplant cells. Nat Methods. 2009;6(12):917–22. doi: 10.1038/nmeth.1401 19915560.

45. Ghaemmaghami S, Huh WK, Bower K, Howson RW, Belle A, Dephoure N, et al. Global analysis of protein expression in yeast. Nature. 2003;425(6959):737–41. doi: 10.1038/nature02046 14562106.

46. Foiani M, Pellicioli A, Lopes M, Lucca C, Ferrari M, Liberi G, et al. DNA damage checkpoints and DNA replication controls in Saccharomyces cerevisiae. Mutat Res. 2000;451(1–2):187–96. doi: 10.1016/s0027-5107(00)00049-x 10915872

47. Zhang Y, Hunter T. Roles of Chk1 in cell biology and cancer therapy. Int J Cancer. 2014;134(5):1013–23. doi: 10.1002/ijc.28226 23613359; PubMed Central PMCID: PMC3852170.

48. Shimada K, Pasero P, Gasser SM. ORC and the intra-S-phase checkpoint: a threshold regulates Rad53p activation in S phase. Genes Dev. 2002;16(24):3236–52. doi: 10.1101/gad.239802 12502744.

49. Tercero JA, Longhese MP, Diffley JF. A central role for DNA replication forks in checkpoint activation and response. Mol Cell. 2003;11(5):1323–36. doi: 10.1016/s1097-2765(03)00169-2 12769855.

50. Feng W, Di Rienzi SC, Raghuraman MK, Brewer BJ. Replication stress-induced chromosome breakage is correlated with replication fork progression and is preceded by single-stranded DNA formation. G3 (Bethesda). 2011;1(5):327–35. doi: 10.1534/g3.111.000554 22384343; PubMed Central PMCID: PMC3276152.

51. Cha RS, Kleckner N. ATR homolog Mec1 promotes fork progression, thus averting breaks in replication slow zones. Science. 2002;297(5581):602–6. doi: 10.1126/science.1071398 12142538.

52. Hennessy KM, Lee A, Chen E, Botstein D. A group of interacting yeast DNA replication genes. Genes Dev. 1991;5(6):958–69. doi: 10.1101/gad.5.6.958 2044962

53. Ellison EL, Vogt VM. Interaction of the intron-encoded mobility endonuclease I-PpoI with its target site. Mol Cell Biol. 1993;13(12):7531–9. doi: 10.1128/mcb.13.12.7531 8246971; PubMed Central PMCID: PMC364825.

54. Lowery R, Hung L, Knoche K, Bandziulis R. Properties of I-PpoI: a rare-cutting intron-encoded endonuclease. Promega Notes. 1992;38:8–12.

55. Venema J, Tollervey D. Ribosome synthesis in Saccharomyces cerevisiae. Annu Rev Genet. 1999;33:261–311. doi: 10.1146/annurev.genet.33.1.261 10690410.

56. Kouprina NY, Larionov VL. The study of a rDNA replicator in Saccharomyces. Curr Genet. 1983;7:433–8. doi: 10.1007/BF00377608 24173449

57. Kwan EX, Foss EJ, Tsuchiyama S, Alvino GM, Kruglyak L, Kaeberlein M, et al. A natural polymorphism in rDNA replication origins links origin activation with calorie restriction and lifespan. PLoS Genet. 2013;9(3):e1003329. doi: 10.1371/journal.pgen.1003329 23505383; PubMed Central PMCID: PMC3591295.

58. Miller CA, Kowalski D. cis-acting components in the replication origin from ribosomal DNA of Saccharomyces cerevisiae. Mol Cell Biol. 1993;13(9):5360–9. doi: 10.1128/mcb.13.9.5360 8355687

59. Fritze CE, Verschueren K, Strich R, Easton Esposito R. Direct evidence for SIR2 modulation of chromatin structure in yeast rDNA. EMBO J. 1997;16(21):6495–509. doi: 10.1093/emboj/16.21.6495 9351831; PubMed Central PMCID: PMC1170255.

60. Muller M, Lucchini R, Sogo JM. Replication of yeast rDNA initiates downstream of transcriptionally active genes. Mol Cell. 2000;5(5):767–77. doi: 10.1016/s1097-2765(00)80317-2 10882113.

61. Pasero P, Bensimon A, Schwob E. Single-molecule analysis reveals clustering and epigenetic regulation of replication origins at the yeast rDNA locus. Genes Dev. 2002;16(19):2479–84. doi: 10.1101/gad.232902 12368258

62. Muller CA, Hawkins M, Retkute R, Malla S, Wilson R, Blythe MJ, et al. The dynamics of genome replication using deep sequencing. Nucleic Acids Res. 2014;42(1):e3. doi: 10.1093/nar/gkt878 24089142; PubMed Central PMCID: PMC3874191.

63. Zegerman P, Diffley JF. Checkpoint-dependent inhibition of DNA replication initiation by Sld3 and Dbf4 phosphorylation. Nature. 2010;467(7314):474–8. doi: 10.1038/nature09373 20835227; PubMed Central PMCID: PMC2948544.

64. Zhong Y, Nellimoottil T, Peace JM, Knott SR, Villwock SK, Yee JM, et al. The level of origin firing inversely affects the rate of replication fork progression. J Cell Biol. 2013;201(3):373–83. doi: 10.1083/jcb.201208060 23629964; PubMed Central PMCID: PMC3639389.

65. Feng W, Collingwood D, Boeck ME, Fox LA, Alvino GM, Fangman WL, et al. Genomic mapping of single-stranded DNA in hydroxyurea-challenged yeasts identifies origins of replication. Nat Cell Biol. 2006;8(2):148–55. doi: 10.1038/ncb1358 16429127.

66. Peng J, Feng W. Incision of damaged DNA in the presence of an impaired Smc5/6 complex imperils genome stability. Nucleic Acids Res. 2016;44(21):10216–29. doi: 10.1093/nar/gkw720 27536003; PubMed Central PMCID: PMC5137426.

67. Haruki H, Nishikawa J, Laemmli UK. The anchor-away technique: rapid, conditional establishment of yeast mutant phenotypes. Mol Cell. 2008;31(6):925–32. doi: 10.1016/j.molcel.2008.07.020 18922474.

68. Cayrou C, Coulombe P, Vigneron A, Stanojcic S, Ganier O, Peiffer I, et al. Genome-scale analysis of metazoan replication origins reveals their organization in specific but flexible sites defined by conserved features. Genome Res. 2011;21(9):1438–49. doi: 10.1101/gr.121830.111 21750104; PubMed Central PMCID: PMC3166829.

69. Petryk N, Kahli M, d'Aubenton-Carafa Y, Jaszczyszyn Y, Shen Y, Silvain M, et al. Replication landscape of the human genome. Nat Commun. 2016;7:10208. doi: 10.1038/ncomms10208 26751768; PubMed Central PMCID: PMC4729899.

70. Yabuki N, Terashima H, Kitada K. Mapping of early firing origins on a replication profile of budding yeast. Genes Cells. 2002;7(8):781–9. 12167157

71. Belsky JA, MacAlpine HK, Lubelsky Y, Hartemink AJ, MacAlpine DM. Genome-wide chromatin footprinting reveals changes in replication origin architecture induced by pre-RC assembly. Genes Dev. 2015;29(2):212–24. doi: 10.1101/gad.247924.114 25593310; PubMed Central PMCID: PMC4298139.

72. Azmi IF, Watanabe S, Maloney MF, Kang S, Belsky JA, MacAlpine DM, et al. Nucleosomes influence multiple steps during replication initiation. Elife. 2017;6. doi: 10.7554/eLife.22512 28322723; PubMed Central PMCID: PMC5400510.

73. Kohler C, Koalick D, Fabricius A, Parplys AC, Borgmann K, Pospiech H, et al. Cdc45 is limiting for replication initiation in humans. Cell Cycle. 2016;15(7):974–85. doi: 10.1080/15384101.2016.1152424 26919204; PubMed Central PMCID: PMC4889307.

74. Kobayashi T. The replication fork barrier site forms a unique structure with Fob1p and inhibits the replication fork. Mol Cell Biol. 2003;23(24):9178–88. doi: 10.1128/MCB.23.24.9178-9188.2003 14645529; PubMed Central PMCID: PMC309713.

75. Casper AM, Mieczkowski PA, Gawel M, Petes TD. Low levels of DNA polymerase alpha induce mitotic and meiotic instability in the ribosomal DNA gene cluster of Saccharomyces cerevisiae. PLoS Genet. 2008;4(6):e1000105. Epub 2008/06/28. doi: 10.1371/journal.pgen.1000105 18584028; PubMed Central PMCID: PMC2430618.

76. Ide S, Watanabe K, Watanabe H, Shirahige K, Kobayashi T, Maki H. Abnormality in initiation program of DNA replication is monitored by the highly repetitive rRNA gene array on chromosome XII in budding yeast. Mol Cell Biol. 2007;27(2):568–78. doi: 10.1128/MCB.00731-06 17101800; PubMed Central PMCID: PMC1800804.

77. Salim D, Bradford WD, Freeland A, Cady G, Wang J, Pruitt SC, et al. DNA replication stress restricts ribosomal DNA copy number. PLoS Genet. 2017;13(9):e1007006. doi: 10.1371/journal.pgen.1007006 28915237; PubMed Central PMCID: PMC5617229.

78. Sanchez JC, Kwan EX, Pohl TJ, Amemiya HM, Raghuraman MK, Brewer BJ. Defective replication initiation results in locus specific chromosome breakage and a ribosomal RNA deficiency in yeast. PLoS Genet. 2017;13(10):e1007041. doi: 10.1371/journal.pgen.1007041 29036220; PubMed Central PMCID: PMC5658192.

79. Stults DM, Killen MW, Pierce HH, Pierce AJ. Genomic architecture and inheritance of human ribosomal RNA gene clusters. Genome Res. 2008;18(1):13–8. doi: 10.1101/gr.6858507 18025267; PubMed Central PMCID: PMC2134781.

80. Melters DP, Bradnam KR, Young HA, Telis N, May MR, Ruby JG, et al. Comparative analysis of tandem repeats from hundreds of species reveals unique insights into centromere evolution. Genome Biol. 2013;14(1):R10. doi: 10.1186/gb-2013-14-1-r10 23363705; PubMed Central PMCID: PMC4053949.

81. Willard HF. Centromeres of mammalian chromosomes. Trends Genet. 1990;6(12):410–6. doi: 10.1016/0168-9525(90)90302-m 2087784.

82. Alvino GM, Collingwood D, Murphy JM, Delrow J, Brewer BJ, Raghuraman MK. Replication in hydroxyurea: it's a matter of time. Mol Cell Biol. 2007;27(18):6396–406. doi: 10.1128/MCB.00719-07 17636020.

83. Kwan EX, Wang XS, Amemiya HM, Brewer BJ, Raghuraman MK. rDNA Copy number variants are frequent passenger mutations in Saccharomyces cerevisiae deletion collections and de novo transformants. G3 (Bethesda). 2016;6(9):2829–38. doi: 10.1534/g3.116.030296 27449518; PubMed Central PMCID: PMC5015940.

84. Rose MD, Winston F, Hieter P. A ten-minute DNA preparation from yeast. Methods in Yeast Genetics: A Laboratory Course Manual. Cold Spring Harbor, New York: Cold Spring Harbor Laboratory Press; 1990. p. 131–2.

85. Payen C, Di Rienzi SC, Ong GT, Pogachar JL, Sanchez JC, Sunshine AB, et al. The dynamics of diverse segmental amplifications in populations of Saccharomyces cerevisiae adapting to strong selection. G3 (Bethesda). 2014;4(3):399–409. doi: 10.1534/g3.113.009365 24368781; PubMed Central PMCID: PMC3962480.

86. Siow CC, Nieduszynska SR, Muller CA, Nieduszynski CA. OriDB, the DNA replication origin database updated and extended. Nucleic Acids Res. 2012;40(Database issue):D682–6. doi: 10.1093/nar/gkr1091 22121216; PubMed Central PMCID: PMC3245157.

87. Sheu YJ, Kinney JB, Lengronne A, Pasero P, Stillman B. Domain within the helicase subunit Mcm4 integrates multiple kinase signals to control DNA replication initiation and fork progression. Proc Natl Acad Sci U S A. 2014;111(18):E1899–908. doi: 10.1073/pnas.1404063111 24740181; PubMed Central PMCID: PMC4020090.