The procaryotic transposon Tn5 inserts into many different sites within a single gene, but some sites (hotspots) are targeted repeatedly. Hotspots are not closely related in sequence, but most have G/C pairs at the ends of the nine base pairs duplicated by Tn5 insertion. In pBR322, the major hotspot coincides with the "-10 region" of the tet promoter. We mutated the G/C pairs at this hotspot an...

Tn5 is a composite bacterial transposon that encodes a protein, transposase (Tnp), required for movement of the transposon. The initial step in the transposition pathway involves specific binding of Tnp to 19-bp end recognition sequences. Tn5 contains two different specific end sequences, termed outside end (OE) and inside end (IE). In Escherichia coli, IE is methylated by Dam methylase (IE(ME)...

Genomic evolution has been profoundly influenced by DNA transposition, a process whereby defined DNA segments move freely about the genome. Transposition is mediated by transposases, and similar events are catalyzed by retroviral integrases such as human immunodeficiency virus-1 (HIV-1) integrase. Understanding how these proteins interact with DNA is central to understanding the molecular basis...

We approached the identification of Ensifer (Sinorhizobium) meliloti conjugal functions by random Tn5-B13 mutagenesis of the pSmeLPU88a plasmid of E. meliloti strain LPU88 and the subsequent selection of those mutants that had lost the ability to mobilize the small plasmid pSmeLPU88b. The Tn5-B13-insertion site of one of the mutants was cloned as an EcoRI-restricted DNA fragment that after subs...

This communication reports an analysis of Tn5yIS50 target site selection by using an extensive collection of Tn5 and IS50 insertions in two relatively small regions of DNA (less than 1 kb each). For both regions data were collected resulting from in vitro and in vivo transposition events. Since the data sets are consistent and transposase was the only protein present in vitro, this demonstrates...

Transposon Tn5 encodes streptomycin resistance in addition to kanamycin-neomycin resistance. This resistance was not detectable in Escherichia coli but was efficiently expressed in Rhizobium meliloti and certain other strains. By analysis of cloned Tn5 restriction endonuclease fragments, the streptomycin resistance (str) gene was located in the right-hand side of the central region as the trans...