The chromosomal DNA ofStreptomyces lividans66 is linear

摘要

SummaryTwo copies of a DNA sequence similar or identical to one end of the linear plasmid SLP2 were found on theStreptomyces lividanschromosome. Restriction mapping showed that these sequences represented free ends. Electrophoretic retardation and glass‐binding studies indicated that the telomeres carry covalently bound proteins. Moreover, the chromosome migrated as an 8Mb linear DNA in pulsed‐field gel electrophoresis. A similar finding with the chromosomes of six otherStreptomycesspecies suggested that a linear chromosome may be characteristic of the genus. TheS. lividanschromosome can be circularized by joining the two ends by artificial targeted recombination or by spontaneous deletions spanning both telomeres. Thus the chromosome appears to be able to exist, in viable bacteria, as a linear or a circular molec