Analysis of functions in plasmid pHZ1358 influencing its genetic and structural stability in Streptomyces lividans 1326
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- Sun, Y., He, X., Liang, J. et al. Appl Microbiol Biotechnol (2009) 82: 303. doi:10.1007/s00253-008-1793-7
The complete DNA sequence of plasmid pHZ1358, a widely used vector for targeted gene disruption and replacement experiments in many Streptomyces hosts, has been determined. This has allowed a detailed analysis of the basis of its structural and segregational instability, compared to the high copy number plasmid pIJ101 of Streptomyces lividans 1326 from which it was derived. A 574-bp DNA region containing sti (strong incompatibility locus) was found to be a determinant for segregational instability in its original S. lividans 1326 host, while the structural instability was found to be related to the facile deletion of the entire Escherichia coli-derived part of pHZ1358, mediated by recombination between 36-bp direct repeats. A point mutation removing the BamHI site inside the rep gene encoding a replication protein (rep*) and/or a spontaneous deletion of the 694-bp region located between rep and sti including the uncharacterized ORF85 (orf85−) produced little or no effect on stability. A pHZ1358 derivative (pJTU412, sti−, rep*, orf85−) was then constructed which additionally lacked one of the 36-bp direct repeats. pJTU412 was demonstrated to be structurally stable but segregationally unstable and, in contrast to sti+ pHZ1358, allowed efficient targeted gene replacement in S. lividans 1326.