Some uses of Transposons
- Transposon insertions can be isolated at a large number of sites on the bacterial chromosome. In principle, it is possible to find transposon insertions in any nonessential gene in the genome.
- A transposon insertion in a gene usually causes complete loss of function. With a few rare exceptions, transposon insertion mutations are null alleles.
- The phenotype of the insertion mutation is completely linked to antibiotic resistance in genetic crosses. Therefore, it is possible to transfer the mutation into a new strain by selecting for antibiotic resistance.
- Insertion mutants can be recovered at high frequency after low-level mutagenesis. Thus, the resulting mutant phenotype is unlikely to be due to multiple transposon insertion mutations. It is possible show that the mutant phenotype is due to the transposon insertion by a genetic backcross.
- Loss of the transposon insertion results in concomitant loss of the associated antibiotic resistance.
- Insertions in operons are usually strongly polar. Thus, transposon insertions can be used to determine whether genes are in an operon.
- Insertions can be obtained which are near but not within a gene of interest. (Such insertions are useful for constructing deletions, and for genetic mapping.)
- Insertions behave as point mutations in fine-structure genetic mapping.
- Transposons can provide a portable region of homology. Thus, recombination between transposons can be used to construct deletions or duplications with defined endpoints, or to form cointegrates between different genetic elements.
- Special transposons can be used to construct operon or gene fusions to reporter genes.
Kleckner, N., J. Roth, and D. Botstein. 1977. Genetic engineering in vivo using translocatable drug-resistance elements. New methods in bacterial genetics. J. Mol. Biol. 116: 125-159.
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Last modified October 14, 2003