THE STREPTOMYCES-LIVIDANS 66-CHROMOSOME CONTAINS A 1 MB DELETOGENIC REGION FLANKED BY 2 AMPLIFIABLE REGIONS

Genetic instability in Streptomyces species often involves large delet ions sometimes accompanied by DNA amplification. Two such systems in S treptomyces lividans 66 involve the production of mutants sensitive to chloramphenicol and the production of mutants resistant to the galact ose analogue 2-deoxygalactose, respectively. Overlapping cosmids were isolated that span the ca. 1 Mb region between the two amplifiable reg ions. The structure of the region was confirmed by restriction mapping using the rarely cutting enzymes AseI, BfrI and DraI and pulsed-field gel electrophoresis. The region contains a non-clonable gap flanked b y inverted repeats; the structure is consistent with the presence of a physical gap, i.e. a linear chromosome.