Basis of Transposition and Gene Amplification by Tn1721 and Related Tetracycline-resistance Transposons
This extract was created in the absence of an abstract.
Excerpt
A novel property of transposable elements has been detected in the closely related tetracycline-resistance (Tcr) transposons Tn1721 and Tn1771, i.e., the ability to amplify a 5.3-kb portion comprising the drug-resistance genes (tet region). A model accounting for both recA-dependent gene amplification and recA-independent transposition to other replicons is shown in Figure 1 (Schmitt et al. 1979; Schöffl and Pühler 1979). The salient features include three identical repeats, two of which bracket the repetitious tet region in direct orientation; the third, inversely oriented, is located at one terminus of the minor transposon. Each repeat contains an EcoRI restriction site. These repeat sequences divide Tn1721 into two domains, one responsible for translocation and the other responsible for drug resistance. This paper includes (1) results in support of this model and a discussion of (2) the possible origin and (3) physiological significance of transposons like Tn1721.
RESULTS AND DISCUSSION
The 5.3 kb EcoRI...
