Skip to main content
NCBI home page
Nucleic Acids Research logoLink to Nucleic Acids Research
. 1990 Aug 25;18(16):4763–4770.

Structural and functional analysis of temperature-sensitive mutants of the phage phi 29 DNA polymerase.

M A Blasco 1, L Blanco 1, E Parés 1, M Salas 1, A Bernad 1
PMCID: PMC331939  PMID: 2118623

Abstract

The cloning and complete sequencing of gene 2 from four independently isolated temperature-sensitive mutants in the phage phi 29 DNA polymerase (ts2 mutants) is reported. The results obtained indicate that, in vivo, the mutations only affect the initial steps of the replication process. Interestingly, three of these mutations consist in the single amino acid change Ala to Val at position 492 of the protein. The ts2(24) and ts2(98) mutant phi 29 DNA polymerases were expressed, purified and their thermosensitivity was studied at two different steps of DNA replication: 1) protein-primed initiation and 2) elongation of the DNA chain. Whereas the ts2(24) mutation gave rise to a temperature-sensitive phenotype in both reactions, the ts2(98) mutant protein was rather insensitive to the temperature increase. In addition, the ts2(98) mutant protein showed clear differences in the activation by divalent cations. The relationship of these results with structural and functional domains in the phi 29 DNA polymerase are discussed.

Full text

PDF
4763

Images in this article

4768Image
on p.4768
4769Image
on p.4769
4769Image
on p.4769

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Alber T., Sun D. P., Nye J. A., Muchmore D. C., Matthews B. W. Temperature-sensitive mutations of bacteriophage T4 lysozyme occur at sites with low mobility and low solvent accessibility in the folded protein. Biochemistry. 1987 Jun 30;26(13):3754–3758. doi: 10.1021/bi00387a002. [DOI] [PubMed] [Google Scholar]
  2. Aleström P., Akusjärvi G., Pettersson M., Pettersson U. DNA sequence analysis of the region encoding the terminal protein and the hypothetical N-gene product of adenovirus type 2. J Biol Chem. 1982 Nov 25;257(22):13492–13498. [PubMed] [Google Scholar]
  3. Baer R., Bankier A. T., Biggin M. D., Deininger P. L., Farrell P. J., Gibson T. J., Hatfull G., Hudson G. S., Satchwell S. C., Séguin C. DNA sequence and expression of the B95-8 Epstein-Barr virus genome. Nature. 1984 Jul 19;310(5974):207–211. doi: 10.1038/310207a0. [DOI] [PubMed] [Google Scholar]
  4. Bernad A., Blanco L., Lázaro J. M., Martín G., Salas M. A conserved 3'----5' exonuclease active site in prokaryotic and eukaryotic DNA polymerases. Cell. 1989 Oct 6;59(1):219–228. doi: 10.1016/0092-8674(89)90883-0. [DOI] [PubMed] [Google Scholar]
  5. Bernad A., Lázaro J. M., Salas M., Blanco L. The highly conserved amino acid sequence motif Tyr-Gly-Asp-Thr-Asp-Ser in alpha-like DNA polymerases is required by phage phi 29 DNA polymerase for protein-primed initiation and polymerization. Proc Natl Acad Sci U S A. 1990 Jun;87(12):4610–4614. doi: 10.1073/pnas.87.12.4610. [DOI] [PMC free article] [PubMed] [Google Scholar]
  6. Bernad A., Zaballos A., Salas M., Blanco L. Structural and functional relationships between prokaryotic and eukaryotic DNA polymerases. EMBO J. 1987 Dec 20;6(13):4219–4225. doi: 10.1002/j.1460-2075.1987.tb02770.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  7. Binns M. M., Stenzler L., Tomley F. M., Campbell J., Boursnell M. E. Identification by a random sequencing strategy of the fowlpoxvirus DNA polymerase gene, its nucleotide sequence and comparison with other viral DNA polymerases. Nucleic Acids Res. 1987 Aug 25;15(16):6563–6573. doi: 10.1093/nar/15.16.6563. [DOI] [PMC free article] [PubMed] [Google Scholar]
  8. Birnboim H. C., Doly J. A rapid alkaline extraction procedure for screening recombinant plasmid DNA. Nucleic Acids Res. 1979 Nov 24;7(6):1513–1523. doi: 10.1093/nar/7.6.1513. [DOI] [PMC free article] [PubMed] [Google Scholar]
  9. Blanco L., García J. A., Salas M. Cloning and expression of gene 2, required for the protein-primed initiation of the Bacillus subtilis phage phi 29 DNA replication. Gene. 1984 Jul-Aug;29(1-2):33–40. doi: 10.1016/0378-1119(84)90163-x. [DOI] [PubMed] [Google Scholar]
  10. Blanco L., Prieto I., Gutiérrez J., Bernad A., Lázaro J. M., Hermoso J. M., Salas M. Effect of NH4+ ions on phi 29 DNA-protein p3 replication: formation of a complex between the terminal protein and the DNA polymerase. J Virol. 1987 Dec;61(12):3983–3991. doi: 10.1128/jvi.61.12.3983-3991.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  11. Blanco L., Salas M. Characterization and purification of a phage phi 29-encoded DNA polymerase required for the initiation of replication. Proc Natl Acad Sci U S A. 1984 Sep;81(17):5325–5329. doi: 10.1073/pnas.81.17.5325. [DOI] [PMC free article] [PubMed] [Google Scholar]
  12. Blanco L., Salas M. Characterization of a 3'----5' exonuclease activity in the phage phi 29-encoded DNA polymerase. Nucleic Acids Res. 1985 Feb 25;13(4):1239–1249. doi: 10.1093/nar/13.4.1239. [DOI] [PMC free article] [PubMed] [Google Scholar]
  13. Blanco L., Salas M. Effect of aphidicolin and nucleotide analogs on the phage phi 29 DNA polymerase. Virology. 1986 Sep;153(2):179–187. doi: 10.1016/0042-6822(86)90021-8. [DOI] [PubMed] [Google Scholar]
  14. Blanco L., Salas M. Replication of phage phi 29 DNA with purified terminal protein and DNA polymerase: synthesis of full-length phi 29 DNA. Proc Natl Acad Sci U S A. 1985 Oct;82(19):6404–6408. doi: 10.1073/pnas.82.19.6404. [DOI] [PMC free article] [PubMed] [Google Scholar]
  15. Bolivar F., Rodriguez R. L., Greene P. J., Betlach M. C., Heyneker H. L., Boyer H. W., Crosa J. H., Falkow S. Construction and characterization of new cloning vehicles. II. A multipurpose cloning system. Gene. 1977;2(2):95–113. [PubMed] [Google Scholar]
  16. Boulet A., Simon M., Faye G., Bauer G. A., Burgers P. M. Structure and function of the Saccharomyces cerevisiae CDC2 gene encoding the large subunit of DNA polymerase III. EMBO J. 1989 Jun;8(6):1849–1854. doi: 10.1002/j.1460-2075.1989.tb03580.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  17. Brutlag D., Kornberg A. Enzymatic synthesis of deoxyribonucleic acid. 36. A proofreading function for the 3' leads to 5' exonuclease activity in deoxyribonucleic acid polymerases. J Biol Chem. 1972 Jan 10;247(1):241–248. [PubMed] [Google Scholar]
  18. Carrascosa J. L., Camacho A., Moreno F., Jiménez F., Mellado R. P., Viñuela E., Salas M. Bacillus subtilis phage phi29. Characterization of gene products and functions. Eur J Biochem. 1976 Jul 1;66(2):229–241. doi: 10.1111/j.1432-1033.1976.tb10512.x. [DOI] [PubMed] [Google Scholar]
  19. Carrascosa J. L., Viñuela E., Salas M. Proteins induced in Bacillus subtilis infected with bacteriophage phi 29. Virology. 1973 Nov;56(1):291–299. [PubMed] [Google Scholar]
  20. Davison A. J., Scott J. E. The complete DNA sequence of varicella-zoster virus. J Gen Virol. 1986 Sep;67(Pt 9):1759–1816. doi: 10.1099/0022-1317-67-9-1759. [DOI] [PubMed] [Google Scholar]
  21. De Waard A., Paul A. V., Lehman I. R. The structural gene for deoxyribonucleic acid polymerase in bacteriophages T4 and T5. Proc Natl Acad Sci U S A. 1965 Oct;54(4):1241–1248. doi: 10.1073/pnas.54.4.1241. [DOI] [PMC free article] [PubMed] [Google Scholar]
  22. Derbyshire V., Freemont P. S., Sanderson M. R., Beese L., Friedman J. M., Joyce C. M., Steitz T. A. Genetic and crystallographic studies of the 3',5'-exonucleolytic site of DNA polymerase I. Science. 1988 Apr 8;240(4849):199–201. doi: 10.1126/science.2832946. [DOI] [PubMed] [Google Scholar]
  23. Devereux J., Haeberli P., Smithies O. A comprehensive set of sequence analysis programs for the VAX. Nucleic Acids Res. 1984 Jan 11;12(1 Pt 1):387–395. doi: 10.1093/nar/12.1part1.387. [DOI] [PMC free article] [PubMed] [Google Scholar]
  24. Earl P. L., Jones E. V., Moss B. Homology between DNA polymerases of poxviruses, herpesviruses, and adenoviruses: nucleotide sequence of the vaccinia virus DNA polymerase gene. Proc Natl Acad Sci U S A. 1986 Jun;83(11):3659–3663. doi: 10.1073/pnas.83.11.3659. [DOI] [PMC free article] [PubMed] [Google Scholar]
  25. Gibbs J. S., Chiou H. C., Hall J. D., Mount D. W., Retondo M. J., Weller S. K., Coen D. M. Sequence and mapping analyses of the herpes simplex virus DNA polymerase gene predict a C-terminal substrate binding domain. Proc Natl Acad Sci U S A. 1985 Dec;82(23):7969–7973. doi: 10.1073/pnas.82.23.7969. [DOI] [PMC free article] [PubMed] [Google Scholar]
  26. Grütter M. G., Gray T. M., Weaver L. H., Wilson T. A., Matthews B. W. Structural studies of mutants of the lysozyme of bacteriophage T4. The temperature-sensitive mutant protein Thr157----Ile. J Mol Biol. 1987 Sep 20;197(2):315–329. doi: 10.1016/0022-2836(87)90126-4. [DOI] [PubMed] [Google Scholar]
  27. Imoto T., Yamada H., Yasukochi T., Yamada E., Ito Y., Ueda T., Nagatani H., Miki T., Horiuchi T. Point mutation of alanine (31) to valine prohibits the folding of reduced lysozyme by sulfhydryl-disulfide interchange. Protein Eng. 1987 Aug-Sep;1(4):333–338. doi: 10.1093/protein/1.4.333. [DOI] [PubMed] [Google Scholar]
  28. Inciarte M. R., Viñuela E., Salas M. Transcription in vitro of phi29 DNA and EcoRI fragments by Bacillus subtilis RNA polymerase. Eur J Biochem. 1976 Dec;71(1):77–83. doi: 10.1111/j.1432-1033.1976.tb11091.x. [DOI] [PubMed] [Google Scholar]
  29. Jiménez F., Camacho A., De La Torre J., Viñuela E., Salas M. Assembly of Bacillus subtilis phage phe29. 2. Mutants in the cistrons coding for the non-structural proteins. Eur J Biochem. 1977 Feb 15;73(1):57–72. doi: 10.1111/j.1432-1033.1977.tb11291.x. [DOI] [PubMed] [Google Scholar]
  30. Kempken F., Meinhardt F., Esser K. In organello replication and viral affinity of linear, extrachromosomal DNA of the ascomycete Ascobolus immersus. Mol Gen Genet. 1989 Sep;218(3):523–530. doi: 10.1007/BF00332419. [DOI] [PubMed] [Google Scholar]
  31. Kouzarides T., Bankier A. T., Satchwell S. C., Weston K., Tomlinson P., Barrell B. G. Sequence and transcription analysis of the human cytomegalovirus DNA polymerase gene. J Virol. 1987 Jan;61(1):125–133. doi: 10.1128/jvi.61.1.125-133.1987. [DOI] [PMC free article] [PubMed] [Google Scholar]
  32. Laemmli U. K. Cleavage of structural proteins during the assembly of the head of bacteriophage T4. Nature. 1970 Aug 15;227(5259):680–685. doi: 10.1038/227680a0. [DOI] [PubMed] [Google Scholar]
  33. Loeb L. A., Dube D. K., Beckman R. A., Koplitz M., Gopinathan K. P. On the fidelity of DNA replication. Nucleoside monophosphate generation during polymerization. J Biol Chem. 1981 Apr 25;256(8):3978–3987. [PubMed] [Google Scholar]
  34. Loeber G., Tevethia M. J., Schwedes J. F., Tegtmeyer P. Temperature-sensitive mutants identify crucial structural regions of simian virus 40 large T antigen. J Virol. 1989 Oct;63(10):4426–4430. doi: 10.1128/jvi.63.10.4426-4430.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  35. Matsumoto K., Takano H., Kim C. I., Hirokawa H. Primary structure of bacteriophage M2 DNA polymerase: conserved segments within protein-priming DNA polymerases and DNA polymerase I of Escherichia coli. Gene. 1989 Dec 14;84(2):247–255. doi: 10.1016/0378-1119(89)90498-8. [DOI] [PubMed] [Google Scholar]
  36. McQuire J. C., Gilpatrick M. W., Pène J. J. DNA replication of bacteriophage phi29. Effect of two viral genes on the association of phage chromosomes with the host cell membrane. Virology. 1977 May 1;78(1):234–240. doi: 10.1016/0042-6822(77)90094-0. [DOI] [PubMed] [Google Scholar]
  37. Mellado R. P., Moreno F., Viñuela E., Salas M., Reilly B. E., Anderson D. L. Genetic analysis of bacteriophage phi 29 of Bacillus subtilis: integration and mapping of reference mutants of two collections. J Virol. 1976 Aug;19(2):495–500. doi: 10.1128/jvi.19.2.495-500.1976. [DOI] [PMC free article] [PubMed] [Google Scholar]
  38. Mellado R. P., Peñalva M. A., Inciarte M. R., Salas M. The protein covalently linked to the 5' termini of the DNA of Bacillus subtilis phage phi 29 is involved in the initiation of DNA replication. Virology. 1980 Jul 15;104(1):84–96. doi: 10.1016/0042-6822(80)90367-0. [DOI] [PubMed] [Google Scholar]
  39. Moreno F. Suppressor-sensitive mutants and genetic map of Bacillus subtilis bacteriophage phi 29. Virology. 1974 Nov;62(1):1–16. doi: 10.1016/0042-6822(74)90298-0. [DOI] [PubMed] [Google Scholar]
  40. Morrison A., Christensen R. B., Alley J., Beck A. K., Bernstine E. G., Lemontt J. F., Lawrence C. W. REV3, a Saccharomyces cerevisiae gene whose function is required for induced mutagenesis, is predicted to encode a nonessential DNA polymerase. J Bacteriol. 1989 Oct;171(10):5659–5667. doi: 10.1128/jb.171.10.5659-5667.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  41. Mott J. E., Grant R. A., Ho Y. S., Platt T. Maximizing gene expression from plasmid vectors containing the lambda PL promoter: strategies for overproducing transcription termination factor rho. Proc Natl Acad Sci U S A. 1985 Jan;82(1):88–92. doi: 10.1073/pnas.82.1.88. [DOI] [PMC free article] [PubMed] [Google Scholar]
  42. Muzyczka N., Poland R. L., Bessman M. J. Studies on the biochemical basis of spontaneous mutation. I. A comparison of the deoxyribonucleic acid polymerases of mutator, antimutator, and wild type strains of bacteriophage T4. J Biol Chem. 1972 Nov 25;247(22):7116–7122. [PubMed] [Google Scholar]
  43. Oeser B., Tudzynski P. The linear mitochondrial plasmid pClK1 of the phytopathogenic fungus Claviceps purpurea may code for a DNA polymerase and an RNA polymerase. Mol Gen Genet. 1989 May;217(1):132–140. doi: 10.1007/BF00330952. [DOI] [PubMed] [Google Scholar]
  44. Paillard M., Sederoff R. R., Levings C. S. Nucleotide sequence of the S-1 mitochondrial DNA from the S cytoplasm of maize. EMBO J. 1985 May;4(5):1125–1128. doi: 10.1002/j.1460-2075.1985.tb03749.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  45. Pandey V. N., Williams K. R., Stone K. L., Modak M. J. Photoaffinity labeling of the thymidine triphosphate binding domain in Escherichia coli DNA polymerase I: identification of histidine-881 as the site of cross-linking. Biochemistry. 1987 Dec 1;26(24):7744–7748. doi: 10.1021/bi00398a031. [DOI] [PubMed] [Google Scholar]
  46. Pastrana R., Lázaro J. M., Blanco L., García J. A., Méndez E., Salas M. Overproduction and purification of protein P6 of Bacillus subtilis phage phi 29: role in the initiation of DNA replication. Nucleic Acids Res. 1985 May 10;13(9):3083–3100. doi: 10.1093/nar/13.9.3083. [DOI] [PMC free article] [PubMed] [Google Scholar]
  47. Peñalva M. A., Salas M. Initiation of phage phi 29 DNA replication in vitro: formation of a covalent complex between the terminal protein, p3, and 5'-dAMP. Proc Natl Acad Sci U S A. 1982 Sep;79(18):5522–5526. doi: 10.1073/pnas.79.18.5522. [DOI] [PMC free article] [PubMed] [Google Scholar]
  48. Pizzagalli A., Valsasnini P., Plevani P., Lucchini G. DNA polymerase I gene of Saccharomyces cerevisiae: nucleotide sequence, mapping of a temperature-sensitive mutation, and protein homology with other DNA polymerases. Proc Natl Acad Sci U S A. 1988 Jun;85(11):3772–3776. doi: 10.1073/pnas.85.11.3772. [DOI] [PMC free article] [PubMed] [Google Scholar]
  49. Reha-Krantz L. J. Amino acid changes coded by bacteriophage T4 DNA polymerase mutator mutants. Relating structure to function. J Mol Biol. 1988 Aug 20;202(4):711–724. doi: 10.1016/0022-2836(88)90552-9. [DOI] [PubMed] [Google Scholar]
  50. Reha-Krantz L. J. Locations of amino acid substitutions in bacteriophage T4 tsL56 DNA polymerase predict an N-terminal exonuclease domain. J Virol. 1989 Nov;63(11):4762–4766. doi: 10.1128/jvi.63.11.4762-4766.1989. [DOI] [PMC free article] [PubMed] [Google Scholar]
  51. Rush J., Konigsberg W. H. Photoaffinity labeling of the Klenow fragment with 8-azido-dATP. J Biol Chem. 1990 Mar 25;265(9):4821–4827. [PubMed] [Google Scholar]
  52. Salas M. Initiation of DNA replication by primer proteins: bacteriophage phi 29 and its relatives. Curr Top Microbiol Immunol. 1988;136:71–88. doi: 10.1007/978-3-642-73115-0_4. [DOI] [PubMed] [Google Scholar]
  53. Sanger F., Nicklen S., Coulson A. R. DNA sequencing with chain-terminating inhibitors. Proc Natl Acad Sci U S A. 1977 Dec;74(12):5463–5467. doi: 10.1073/pnas.74.12.5463. [DOI] [PMC free article] [PubMed] [Google Scholar]
  54. Savilahti H., Bamford D. H. The complete nucleotide sequence of the left very early region of Escherichia coli bacteriophage PRD1 coding for the terminal protein and the DNA polymerase. Gene. 1987;57(1):121–130. doi: 10.1016/0378-1119(87)90183-1. [DOI] [PubMed] [Google Scholar]
  55. Spicer E. K., Rush J., Fung C., Reha-Krantz L. J., Karam J. D., Konigsberg W. H. Primary structure of T4 DNA polymerase. Evolutionary relatedness to eucaryotic and other procaryotic DNA polymerases. J Biol Chem. 1988 Jun 5;263(16):7478–7486. [PubMed] [Google Scholar]
  56. Stark M. J., Mileham A. J., Romanos M. A., Boyd A. Nucleotide sequence and transcription analysis of a linear DNA plasmid associated with the killer character of the yeast Kluyveromyces lactis. Nucleic Acids Res. 1984 Aug 10;12(15):6011–6030. doi: 10.1093/nar/12.15.6011. [DOI] [PMC free article] [PubMed] [Google Scholar]
  57. Studier F. W., Moffatt B. A. Use of bacteriophage T7 RNA polymerase to direct selective high-level expression of cloned genes. J Mol Biol. 1986 May 5;189(1):113–130. doi: 10.1016/0022-2836(86)90385-2. [DOI] [PubMed] [Google Scholar]
  58. Tabor S., Richardson C. C. A bacteriophage T7 RNA polymerase/promoter system for controlled exclusive expression of specific genes. Proc Natl Acad Sci U S A. 1985 Feb;82(4):1074–1078. doi: 10.1073/pnas.82.4.1074. [DOI] [PMC free article] [PubMed] [Google Scholar]
  59. Talavera A., Jimenez F., Salas M., Viñuela E. Mapping of temperature sensitive mutants of bacteriophage phi 29. Mol Gen Genet. 1972;115(1):31–35. doi: 10.1007/BF00272215. [DOI] [PubMed] [Google Scholar]
  60. Talavera A., Jimenez F., Salas M., Viñuela E. Temperature-sensitive mutants of bacteriophage phi-29. Virology. 1971 Dec;46(3):586–595. doi: 10.1016/0042-6822(71)90062-6. [DOI] [PubMed] [Google Scholar]
  61. Talavera A., Salas M., Viñuela E. Temperature-sensitive mutants affected in DNA synthesis in phage phi29 of Bacillus subtilis. Eur J Biochem. 1972 Dec 4;31(2):367–371. doi: 10.1111/j.1432-1033.1972.tb02542.x. [DOI] [PubMed] [Google Scholar]
  62. Tomalski M. D., Wu J. G., Miller L. K. The location, sequence, transcription, and regulation of a baculovirus DNA polymerase gene. Virology. 1988 Dec;167(2):591–600. [PubMed] [Google Scholar]
  63. Tommasino M., Ricci S., Galeotti C. L. Genome organization of the killer plasmid pGK12 from Kluyveromyces lactis. Nucleic Acids Res. 1988 Jul 11;16(13):5863–5878. doi: 10.1093/nar/16.13.5863. [DOI] [PMC free article] [PubMed] [Google Scholar]
  64. Watabe K., Leusch M. S., Ito J. A 3' to 5' exonuclease activity is associated with phage 029 DNA polymerase. Biochem Biophys Res Commun. 1984 Sep 28;123(3):1019–1026. doi: 10.1016/s0006-291x(84)80235-1. [DOI] [PubMed] [Google Scholar]
  65. Watabe K., Leusch M., Ito J. Replication of bacteriophage phi 29 DNA in vitro: the roles of terminal protein and DNA polymerase. Proc Natl Acad Sci U S A. 1984 Sep;81(17):5374–5378. doi: 10.1073/pnas.81.17.5374. [DOI] [PMC free article] [PubMed] [Google Scholar]
  66. Wong S. W., Wahl A. F., Yuan P. M., Arai N., Pearson B. E., Arai K., Korn D., Hunkapiller M. W., Wang T. S. Human DNA polymerase alpha gene expression is cell proliferation dependent and its primary structure is similar to both prokaryotic and eukaryotic replicative DNA polymerases. EMBO J. 1988 Jan;7(1):37–47. doi: 10.1002/j.1460-2075.1988.tb02781.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  67. Yanofsky S. D., Love R., McClarin J. A., Rosenberg J. M., Boyer H. W., Greene P. J. Clustering of null mutations in the EcoRI endonuclease. Proteins. 1987;2(4):273–282. doi: 10.1002/prot.340020403. [DOI] [PubMed] [Google Scholar]
  68. Yoshikawa H., Ito J. Nucleotide sequence of the major early region of bacteriophage phi 29. Gene. 1982 Mar;17(3):323–335. doi: 10.1016/0378-1119(82)90149-4. [DOI] [PubMed] [Google Scholar]
  69. Zaballos A., Lázaro J. M., Méndez E., Mellado R. P., Salas M. Effects of internal deletions on the priming activity of the phage phi 29 terminal protein. Gene. 1989 Nov 30;83(2):187–195. doi: 10.1016/0378-1119(89)90104-2. [DOI] [PubMed] [Google Scholar]
  70. Zaballos A., Mellado R. P., Salas M. Initiation of phage phi 29 DNA replication by mutants with deletions at the amino end of the terminal protein. Gene. 1988;63(1):113–121. doi: 10.1016/0378-1119(88)90550-1. [DOI] [PubMed] [Google Scholar]

Articles from Nucleic Acids Research are provided here courtesy of Oxford University Press

RESOURCES