title: [Replication and conjugation of Streptomyces small plasmid pDYM4. 3k].
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.
  
  
  CONCLUSIONS
  Streptomyces small plasmid pDYM4. 3k was able to autonomous replication and conjugal transferring.
authors.affiliation: Key Laboratory of Synthetic Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Sciences, Chinese Academy of Sciences, Shanghai 200032, China. zhoumin1108@gmail.com
authors.forename: Min
authors.initials: M
authors.lastname: Zhou
authors.forename: Yumei
authors.initials: Y
authors.lastname: Dai
authors.forename: Li
authors.initials: L
authors.lastname: Zhong
authors.forename: Zhongjun
authors.initials: Z
authors.lastname: Qin
mesh_terms: D003001:Cloning, Molecular; D021141:Nucleic Acid Amplification Techniques / Q000379:methods*; D010957:Plasmids / Q000096:biosynthesis* / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013302:Streptomyces / Q000235:genetics*