1. Effect of IS3 transposase on lac duplication formation.
Effect of IS3 transposase on lac duplication formation. All strains except the one at the far left have a deletion of the defective IS3B element. For each strain, the two duplication types were determined: IS3 (open columns) and REP plus SJ (red columns). In the third, fourth, and fifth strain, IS3A and IS3C sequences are present but transposase (Tnp) production has been eliminated from one, the other, or both elements by a base substitution in the initiation codon of the tnp gene. In the strain at the far right (shaded column), both IS3A and IS3C were individually replaced by directly oriented copies of the rifR gene, leaving lac flanked by identical sequence repeats with no encoded transposase.
Andrew B. Reams et al. Genetics 2012;192:
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