An improved transposon (ThD73) for Haloarcula hispanica is described, Based
on the halobacterial insertion sequence ISH28, it showed little target seq
uence specificity but was biased toward a lower G+C content. Twenty randoml
y selected ThD73 mutants were analyzed, and the DNA flanking their insertio
ns revealed several recognizable sequences, including two (unrelated) ISH e
lements.