Characterization of plasmid pLP224 from lactobacillus plantarum PC518 and analysis of conservation and diversity of pMV158 plasmid family

Abstract:

[Background] Lactobacillus plantarum has a lot of natural plasmids. Analyzing the sequence characteristics of these plasmids was beneficial to research the genetic information of them. [Objective] To identify a new plasmid isolated from L. plantarum PC518 and analyze conservation and diversity of plasmids belonging to a family. [Methods] Plasmid DNA was isolated from L. plantarum PC518, and two plasmid DNA libraries were constructed after enzyme digestion. New sequences in the libraries were identified by sequencing and BLAST alignment. The whole sequence of the plasmid was completed by reverse PCR. the new plasmid was annotated. The phylogenetic tree of Rep protein was built by MEGA X, and analysis of binding sequence was carried out. [Results] Plasmid pLP224 was a 1 766 bp circular molecule with a (G+C)mol% content of 41.39%. The maximum sequence similarity with known plasmids was 86.85%. pLP224 belonged to the pMV158 family of rolling-circle replication. The results of phylogenetic tree based on Rep protein showed that the closer evolution distance was the higher similarity of binding sequence, and the farther evolution distance was the lower similarity of binding sequence. [Conclusion] pLP224 was a new member of the pMV158 family. The nick sequences of dso site belonging to the pMV158 family were conservative, and the binding sequences belonging to the pMV158 family were diverse. The Rep protein varies with the binding sequence. The difference of Rep protein was conducive to the coexistence in a host, which was the basis for the continuous existence and stable evolution of a family.