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Defining the minimal length of sequence homology required for selective gene isolation by TAR cloning.

  • Noskov, V N
  • Koriabine, M
  • Solomon, G
  • Randolph, M
  • Barrett, J C
  • Leem, S H
  • Stubbs, L
  • Kouprina, N
  • Larionov, V
Published Article
Nucleic Acids Research
Oxford University Press
Publication Date
Mar 15, 2001
PMID: 11239009


The transformation-associated recombination (TAR) cloning technique allows selective and accurate isolation of chromosomal regions and genes from complex genomes. The technique is based on in vivo recombination between genomic DNA and a linearized vector containing homologous sequences, or hooks, to the gene of interest. The recombination occurs during transformation of yeast spheroplasts that results in the generation of a yeast artificial chromosome (YAC) containing the gene of interest. To further enhance and refine the TAR cloning technology, we determined the minimal size of a specific hook required for gene isolation utilizing the Tg.AC mouse transgene as a targeted region. For this purpose a set of vectors containing a B1 repeat hook and a Tg.AC-specific hook of variable sizes (from 20 to 800 bp) was constructed and checked for efficiency of transgene isolation by a radial TAR cloning. When vectors with a specific hook that was >/=60 bp were utilized, approximately 2% of transformants contained circular YACs with the Tg.AC transgene sequences. Efficiency of cloning dramatically decreased when the TAR vector contained a hook of 40 bp or less. Thus, the minimal length of a unique sequence required for gene isolation by TAR is approximately 60 bp. No transgene-positive YAC clones were detected when an ARS element was incorporated into a vector, demonstrating that the absence of a yeast origin of replication in a vector is a prerequisite for efficient gene isolation by TAR cloning.

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