Replication and evolution of Streptomyces plasmids

Abstract:

Recently, with the development of isolating and detecting large plasmids and high-throughput DNA sequencing technology, rapid progresses have been made on Streptomyces large circular and linear plasmids. In contrast to bacterial theta-type plasmids, Streptomyces theta-type plasmids reveal diversity and novelty on the structures of replication origins, functions of replication and regulation proteins. The newly identified replication origins of linear plasmids show that it can also be located near one telomere, and two or more functional origins are observed in one molecule. The newly sequenced telomeres indicate that formation of secondary structure rather than “folding-back” is important for telomere replication. Sequences of Streptomyces circular and linear plasmids imply their close relationship. Sequencing results also show that co-integration of circular plasmid and phage, and experiments demonstrate their inter-conversion under certain conditions. These results indicate that diversity, novelty and evolutionary relationship of Streptomyces circular and linear plasmids and phages.