Replication and conjugation of Streptomyces small plasmid pDYM4. 3k

Abstract:

Abstract:［Objective］ Streptomyces sp.X335，harboring a 4.3-kb plasmid pDYM4.3k，was isolated from Tibet sample． Cloning，sequencing，analyzing and functional investigations of pDYM4. 3k．［Methods］Prime walking to obtain plasmid sequence，BLAST to predict gene function，Southern hybridization to determine replication intermediates，and mating to test conjugal function of plasmid．［Results］The complete nucleotide sequence of pDYM4. 3k consisted of 4346 bp，encoding 3 genes of which one resembled Streptomyces major conjugative gene tra and other two were with unknown functions． Experiments demonstrated that a new gene of pDYM4. 3k and its upstream c． 300 bp were required for plasmid replication． Single-stranded pDYM4. 3k as a replication intermediate was detected，indicating it rolling-cirle replication mode． pDYM4. 3k could conjugal transfer among Streptomyces lividans． ［Conclusion］ Streptomyces small plasmid pDYM4. 3k was able to autonomous replication and conjugal transferring．