STRUCTURAL-ANALYSIS OF THE GIANT LINEAR PLASMID SCP1 IN VARIOUS STREPTOMYCES-COELICOLOR STRAINS

The methylenomycin biosynthetic gene cluster was previously shown to b e present on the 350 kb giant linear plasmid SCP1. The structures of S CP1 in various Streptomyces coelicolor A3(2) strains were analysed by pulsed field gel electrophoresis (PFGE). S. coelicolor A3(2) strains 1 147, M138 and M146, previously genetically characterized as SCP1+, con tained the free form of SCP1. S. coelicolor 1984 and 2106, earlier cha racterized as SCP1'-cysB and a stable cysD donor respectively, were fo und to contain very large linear plasmids, 550 kb and 1700 kb in size. Strain JCM4979, another SCP1+ derivative of A3(2), had a series of SC P1-related linear plasmids of 390-630 kb. The integrated states of SCP 1 in S. coelicolor SCP1-NF strains, an NF-like strain and a stable pab A donor were confirmed by PFGE, which revealed a lack of the intact SC P1 termini. In addition, a 70 kb linear plasmid was found in Streptomy ces violaceoruber SANK95570, another methylenomycin producer. However, the plasmid was shown by hybridization to a methylenomycin resistance gene not to carry the methylenomycin gene cluster of this strain.