Isolation and cloning of Streptomyces terminal fragments

Streptomyces species have a linear chromosome of approximately 8 Mb in size. Many strains also carry linear plasmids. Most of these linear elements contain terminal proteins covalently bound to the 5' ends of the DNA. Using a method for the visualisation of terminal DNA fragments in agarose gels, it was possible to see three fragments in S. rimosus and five fragments in S. avermitilis. The method was also used to clone the 298 bp BamHI fragment carrying the left end of plasmid SLP2. Analysis of the sequence showed that the end resembled other Streptomyces chromosome and plasmid ends, but there were eight palindromes (instead of seven) and a tandem duplication of a 14 bp sequence.