Figure 1.

The structures of the Mu elements examined. (A) The DNA sequence of the terminal inverted repeat (TIR) adjacent to the mudrA gene in MuDR (TIRA). 5′TIRA refers to the first 144 bp of the TIR and includes the known binding site for the MuDR transposase. The Hinf I site has long been diagnostic for methylation in Mu TIRs. The adjacent 3′TIRA includes the last 75 bp of the TIR along with 56 bp of internal sequences corresponding to a portion of the mudrA 5′ UTR, indicated by arrows. This region includes both of the alternative transcriptional start sites for mudrA. (B) A diagram of the structure of MuDR, Muk, and d107. TIRs are indicated as open triangles and exons as shaded boxes. The regions missing in Muk and d107 are indicated by dashed lines. (C) The structure of the Mu1 insertion at a1-mum2. (D) The sequence of the Mu1 TIR, divided into its 5′ and 3′ parts. The transposase binding site is as indicated, as are additional protected sites within the 3′ portion of the Mu1 TIR.