Instability of Tn5 in a plasmid cloning vector for the cyanobacterium Anacystis nidulans.

Transposon Tn5 was used to produce insertions within the region of a cyanobacterial shuttle vector previously identified as necessary for transformation of Anacystis nidulans. These transposon-containing plasmids were used to transform a plasmid-cured derivative of Anacystis strain R2 and tested for structural stability of the transforming plasmid. The transposon DNA was deleted from all the plasmids containing Tn5 within the cyanobacterial replication region. Inserts in the vector DNA were physically stable and expressed the kanr gene. The internal Tn5 HindIII fragment was also cloned into each of the three HindIII sites in the shuttle plasmid. Inserts in two of these sites were stable, whereas inserts into the third site were not.