A linear DNA plasmid from Streptomyces rochei with an inverted terminal repetition of 614 base pairs.

The terminal structure of a linear plasmid pSLA2 , which was isolated from Streptomyces rochei , was analysed. The 5' ends of pSLA2 DNA were blocked by the association of a protein probably covalently bonded with the DNA. This block is removed by alkali treatment and blunt ends with 5'-phosphate and 3'-hydroxy termini were released. The two terminal fragments of pSLA2 were cloned and the nucleotide sequence was determined. An inverted terminal repetition of 614 bp was found along with the presence of further interrupted homologous sequences beyond this area up to 800 bp. These are the first inverted terminal repeat sequences found in microbial linear plasmids.