Molecular and General Genetics MGG

, Volume 197, Issue 2, pp 328–336 | Cite as

A molecular model for conjugational recombination in Escherichia coli K12

  • Robert G. Lloyd
  • Allyn Thomas


Conjugational recombination in Escherichia coli was investigated by measuring lacZ+ product, β-galactosidase, in crosses between lacZ mutants. Enzyme production in both Hfr and F-prime crosses was detected very soon after transfer of the donor lacZ allele. The level of enzyme activity was reduced by no more than two-fold when the recipient carried a recB mutation. With an F-prime donor, recombination appeared to be restricted largely to a short period immediately after transfer, with little evidence of recombination during subsequent exponential growth of the transconjugant cells. These observations are interpreted to suggest that recA dependent recombination is able to initiate with high efficiency at gaps present in the donor DNA before synthesis of a complementary strand is completed, and independently of recB function. A molecular model for conjugational recombination based on this idea is presented in terms of the known activities of recA and recBC products. Some of the predictions of the model are tested by analysing the recombinant genotypes produced in Hfr crosses with multiply marked strains.


Enzyme Escherichia Coli Enzyme Activity Recombination Exponential Growth 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Arthur HM, Lloyd RG (1980) Hyper-recombination in uvrD mutants of Escherichia coli K12. Mol Gen Genet 180:185–191Google Scholar
  2. Bachmann BJ (1972) Pedigrees of some mutant strains of Escherichia coli K-12. Bacteriol Rev 36:525–557Google Scholar
  3. Bachmann BJ (1983) Linkage map of Escherichia coli K12, edition 7. Microbiol Rev 47:180–230Google Scholar
  4. Barbour SD, Nagaishi H, Templin A, Clark AJ (1970) Biochemical and genetic studies of recombination proficiency in Escherichia coli. II Rec+ revertants caused by indirect suppression of Rec- mutations. Proc Natl Acad Sci USA 67:128–135Google Scholar
  5. Birge EA, Low KB (1974) Detection of transcribable recombination products following conjugation in Rec+, RecB-, and RecC- strains of Escherichia coli K12. J Mol Biol 83:447–457Google Scholar
  6. Bresler SE, Krivonogov SV, Lanzov VA (1978) Scale of the genetic map and genetic control of recombination after conjugation in Escherichia coli K12. Mol Gen Genet 166:337–346Google Scholar
  7. Clark AJ (1973) Recombination deficient mutants of E. coli and other bacteria. Annu Rev Genet 7:67–86Google Scholar
  8. Cox MM, Lehman IR (1981) recA protein of Escherichia coli promotes branch migration, a kinetically distinct phase of DNA strand exchange. Proc Natl Acad Sci USA 78:3433–3437Google Scholar
  9. Dower NA, Stahl FW (1981) χ-activity during transduction-associated recombination. Proc Natl Acad Sci USA 78:7033–7037Google Scholar
  10. Ganesan AK, Seawell PC (1975) The effect of lexA and recF mutations on postreplication repair and DNA synthesis in Escherichia coli K12. Mol Gen Genet 141:189–205Google Scholar
  11. Gillen JR, Willis DK, Clark AJ (1981) Genetic analysis of the RecE pathway for genetic recombination in Escherichia coli K-12. J Bacteriol 145:521–532Google Scholar
  12. Hall JD, Howard-Flanders P (1972) Recombinant F′ factors from Escherichia coli K12 strains carrying recB or recC. J Bacteriol 110:578–584Google Scholar
  13. Horii ZI, Clark AJ (1973) Genetic analysis of the RecF pathway to genetic recombination in Escherichia coli K12: isolation and characterisation of mutants. J Mol Biol 80:327–344Google Scholar
  14. Kaiser K, Murray NE (1979) Physical characterization of the “Rac prophage”. Mol Gen Genet 175:159–174Google Scholar
  15. Kingsman A, Willetts N (1978) The requirements for conjugal DNA synthesis in the donor strain during Flac transfer. J Mol Biol 122:287–300Google Scholar
  16. Kolodner R (1980) Genetic recombination of bacterial plasmid DNA: Electron microscopic analysis of in vitro intramolecular recombination. Proc Natl Acad Sci USA 77:4847–4851Google Scholar
  17. Kushner SR, Nagaishi H, Templin A, Clark AJ (1971) Genetic recombination in Escherichia coli: The role of Exonuclease I. Proc Natl Acad Sci USA 68:824–827Google Scholar
  18. Kushner SR, Nagaishi H, Clark AJ (1972) Indirect suppression of recB and recC mutations by Exonuclease I deficiency. Proc Natl Acad Sci USA 69:1366–1370Google Scholar
  19. Laban A, Cohen A (1981) Interplasmidic and intraplasmidic recombination in Escherichia coli K12. Mol Gen Genet 184:200–207Google Scholar
  20. Little JW, Mount DW (1982) The SOS regulatory system of Escherichia coli. Cell 29:11–22Google Scholar
  21. Lloyd RG (1978) Hyper-recombination in Escherichia coli K12 mutants constitutive for protein synthesis. J Bacteriol 134:929–935Google Scholar
  22. Lloyd RG (1983) lexA dependent recombination in uvrD strains of Escherichia coli. Mol Gen Genet 189:157–161Google Scholar
  23. Lloyd RG, Barbour SD (1974) The genetic location of the sbcA gene of Escherichia coli. Mol Gen Genet 134:157–171Google Scholar
  24. Lloyd RG, Johnson S (1979) Kinetics of recA function in conjugational recombinant formation. Mol Gen Genet 169:219–228Google Scholar
  25. Lloyd RG, Low B (1976) Some genetic consequence of changes in the level of recA gene function in Escherichia coli K12. Genetics 84:675–695Google Scholar
  26. Lloyd RG, Thomas A (1983) On the nature of the RecBC and RecF pathways of conjugal recombination in Escherichia coli. Mol Gen Genet 190:156–161Google Scholar
  27. Lloyd RG, Low B, Godson GN, Birge EA (1974) Isolation and characterisation of an Escherichia coli K12 mutant with a temperature-sensitive RecA- phenotye. J Bacteriol 120:407–415Google Scholar
  28. Lloyd RG, Picksley SM, Prescott C (1983) Inducible expression of a gene specific to the RecF pathway for recombination in Escherichia coli K12. Mol Gen Gent 190:162–167Google Scholar
  29. Lloyd RG, Benson FE, Shurvinton CE (1984) Effect of ruv mutations on recombination and DNA repair in Escherichia coli. Mol Gen Genet 194:303–309Google Scholar
  30. Lovett ST, Clark AJ (1983) Genetic analysis of regulation of the RecF pathway of recombination in Escherichia coli K12. J Bacteriol 153:1471–1478Google Scholar
  31. Lovett ST, Clark AJ (1984) Genetic analysis of the recJ gene of Escherichia coli K-12. J Bacteriol 157:199–196Google Scholar
  32. Picksley SM, Attfield PV, Lloyd RG (1984) Repair of DNA double-strand breaks in Escherichia coli K12 requires a functional recN product. Mol Gen Genet 195:267–274Google Scholar
  33. Radding C (1982) Homologous pairing and strand exchange in genetic recombination. Annu Rev Genet 16:405–437Google Scholar
  34. Rothman RH, Clark AJ (1977) The dependence of postreplication repair on uvrB in a recF mutant of Escherichia coli K12. Mol Gen Genet 155:279–286Google Scholar
  35. Shurvinton CE, Lloyd RG (1982) Damage to DNA induces expression of the ruv gene of Escherichia coli. Mol Gen Genet 185:352–355Google Scholar
  36. Siddiqi O, Fox Fox MS (1973) Integration of donor DNA in bacterial conjugation. J Mol Biol 77:101–123Google Scholar
  37. Taylor A, Smith GR (1980) Unwinding and rewinding of DNA by the RecBC enzyme. Cell 22:447–457Google Scholar
  38. Telander-Muskavitch KM, Linn S (1981) A unified mechanism for the nuclease and unwinding activities of the recBC enzyme of Escherichia coli. J Biol Chem 257:2641–2648Google Scholar
  39. Thomas A, Lloyd RG (1980) Altered regulation of the recA gene in Escherichia coli strains carrying a recA-linked suppressor of lexA. Mol gen Genet 179:355–358Google Scholar
  40. Willetts NS, Mount DW (1969) Genetic analysis of recombination-deficient mutants of Escherichia coli K-12 carrying rec mutations cotransducible with thyA. J Bacteriol 100:923–934Google Scholar
  41. Willetts N, Skurray R (1980) The conjugation system of F-like plasmids. Annu Rev Genet 14:41–76Google Scholar

Copyright information

© Springer-Verlag 1984

Authors and Affiliations

  • Robert G. Lloyd
    • 1
  • Allyn Thomas
    • 1
  1. 1.Genetics DepartmentUniversity of NottinghamNottinghamU.K.

Personalised recommendations