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Gene Review

exo  - 

Enterobacteria phage lambda

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Disease relevance of exo

  • Following hybridization of the primer to the r-stand of bacteriophage lambda CI85657, sequences of the newly grown ollgonucleotide chains were determined by a) partial exonuclease digestion followed by two-dimensional fingerprinting; b) determination of pyrimidine tracts; and c) nearest neighbor analyses [1].
  • The gapped plasmid was introduced into Escherichia coli cells expressing the red alpha (exo) and red beta (bet) genes of lambda [2].
  • Through the enzymatic ligation of restriction enzyme fragments, the exo III gene, xth, was transferred to a thermoinducible, integration-proficient lambda phage and to a chimeric ColE1-lambda plasmid that was thermoinducible for lambda-directed DNA replication [3].
  • These results are discussed in terms of a model in which Abc2 converts the RecBCD exonuclease for use in the P22 phage recombination pathway [4].
  • Baculovirus alkaline nuclease possesses a 5'-->3' exonuclease activity and associates with the DNA-binding protein LEF-3 [5].

High impact information on exo

  • The beta protein of bacteriophage lambda acts in homologous genetic recombination by catalyzing the annealing of complementary single-stranded DNA produced by the lambda exonuclease [6].
  • The RecBCD enzyme of Escherichia coli promotes recombination preferentially at chi nucleotide sequences and has in vivo helicase and strong duplex DNA exonuclease (exoV) activities [7].
  • The structure formed at the 5' terminus of the DNA product which blocks phosphorylation by T4 polynucleotide kinase remains unknown, but its removal with phage lambda exonuclease allows at least some reutilization of recognition sites by EcoB as well as phosphorylation of the newly formed 5' termini [8].
  • In this paper, we describe a new strategy, based both on the use of a microsatellite specific probing and on the creation of nested deleted clones with the Exonuclease III, in order to position microsatellites in a range allowing direct sequencing [9].
  • We have used three approaches to studying the interaction of lambda Int protein with bacteriophage attachment site DNA, POP': location of binding sites by retention of DNA fragments in a filter binding assay, reconstruction of a binding site by DNA synthesis and protection of a binding site from an exonuclease [10].

Biological context of exo

  • These plasmids include an origin of replication and a segment of the bacteriophage lambda genome comprising the red genes (exo, bet and gam) under their native control [11].
  • The left termini of these substitutions are formed either by a crossover between the lambda exo gene and a short exo-homologous segment of Qsr' (2/5), or by a crossover between sequences to the left of attL and an unmapped distant region of the host chromosome (3/5) [12].
  • The bacteriophage lambda genes exo and bet, whose products (lambda exonuclease and beta protein, respectively; Red phenotype) mediate homologous recombination of lambda phages, have been cloned under lacPO lacIq control on multi-copy plasmids [13].
  • Of these two recombination proteins, one is an exonuclease whose action on double-stranded DNA produces 3' single-stranded ends; the other, called beta protein, is a DNA binding protein that promotes the renaturation of complementary single strands [14].
  • Use of exonuclease for rapid polymerase-chain-reaction-based in vitro mutagenesis [15].

Associations of exo with chemical compounds

  • However, adeturon do not modify the exonuclease activity [16].
  • Thus, radioprotection mediated by DDC should involve free hydroxyl radical scavenging and a minor activity of exonuclease [16].

Analytical, diagnostic and therapeutic context of exo


  1. The nucleotide sequence in the promoter region of the gene N in bacteriophage lambda. Kleid, D.G., Agarwal, K.L., Khorana, H.G. J. Biol. Chem. (1975) [Pubmed]
  2. Evidence for the double-strand break repair model of bacteriophage lambda recombination. Takahashi, N., Kobayashi, I. Proc. Natl. Acad. Sci. U.S.A. (1990) [Pubmed]
  3. Cloning of the exonuclease III gene of Escherichia coli. Rogers, S.G., Weiss, B. Gene (1980) [Pubmed]
  4. Bacteriophage P22 Abc2 protein binds to RecC increases the 5' strand nicking activity of RecBCD and together with lambda bet, promotes Chi-independent recombination. Murphy, K.C. J. Mol. Biol. (2000) [Pubmed]
  5. Baculovirus alkaline nuclease possesses a 5'-->3' exonuclease activity and associates with the DNA-binding protein LEF-3. Mikhailov, V.S., Okano, K., Rohrmann, G.F. J. Virol. (2003) [Pubmed]
  6. Rings and filaments of beta protein from bacteriophage lambda suggest a superfamily of recombination proteins. Passy, S.I., Yu, X., Li, Z., Radding, C.M., Egelman, E.H. Proc. Natl. Acad. Sci. U.S.A. (1999) [Pubmed]
  7. Interaction with the recombination hot spot chi in vivo converts the RecBCD enzyme of Escherichia coli into a chi-independent recombinase by inactivation of the RecD subunit. Köppen, A., Krobitsch, S., Thoms, B., Wackernagel, W. Proc. Natl. Acad. Sci. U.S.A. (1995) [Pubmed]
  8. The DNA restriction endonuclease of Escherichia coli B. II. Further studies of the structure of DNA intermediates and products. Endlich, B., Linn, S. J. Biol. Chem. (1985) [Pubmed]
  9. A new strategy useful for rapid identification of microsatellites from DNA libraries with large size inserts. Baron, B., Poirier, C., Simon-Chazottes, D., Barnier, C., Guénet, J.L. Nucleic Acids Res. (1992) [Pubmed]
  10. Studies on the binding of lambda Int protein to attachment site DNA: identification of a tight-binding site in the P' region. Davies, R.W., Schreier, P.H., Kotewicz, M.L., Echols, H. Nucleic Acids Res. (1979) [Pubmed]
  11. A set of recombineering plasmids for gram-negative bacteria. Datta, S., Costantino, N., Court, D.L. Gene (2006) [Pubmed]
  12. Structure of cryptic lambda prophages. Redfield, R.J., Campbell, A.M. J. Mol. Biol. (1987) [Pubmed]
  13. Expression of the phage lambda recombination genes exo and bet under lacPO control on a multi-copy plasmid. Zagursky, R.J., Hays, J.B. Gene (1983) [Pubmed]
  14. The beta protein of phage lambda binds preferentially to an intermediate in DNA renaturation. Karakousis, G., Ye, N., Li, Z., Chiu, S.K., Reddy, G., Radding, C.M. J. Mol. Biol. (1998) [Pubmed]
  15. Use of exonuclease for rapid polymerase-chain-reaction-based in vitro mutagenesis. Shyamala, V., Ames, G.F. Gene (1991) [Pubmed]
  16. Radioprotective effect of sodium diethyldithiocarbamate (DDC) and S-2-aminoethyl-isothioronicadenosin-5-triphosphate (adeturon) in gamma-irradiated Escherichia coli cells. Fuentes, J.L., Capetillo, N., Ferrer, M., Padrón, E., Altanés, S., Llagostera, M. Mutat. Res. (1998) [Pubmed]
  17. Isolation and crystallization of lambda exonuclease. van Oostrum, J., White, J.L., Burnett, R.M. Arch. Biochem. Biophys. (1985) [Pubmed]
  18. Optimization of PCR/lambda exonuclease-mediated synthesis of sense and antisense DNA probes for in situ hybridization. Michel, D., Trembleau, A., Moyse, E., Brun, G. Histochem. J. (1997) [Pubmed]
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