کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
2824173 | 1161624 | 2013 | 12 صفحه PDF | دانلود رایگان |
![عکس صفحه اول مقاله: Characterization of pMRI 5.2, a rolling-circle-type plasmid from Lactobacillus plantarum BFE 5092 which harbours two different replication initiation genes Characterization of pMRI 5.2, a rolling-circle-type plasmid from Lactobacillus plantarum BFE 5092 which harbours two different replication initiation genes](/preview/png/2824173.png)
Plasmid pMRI 5.2 from Lactobacillus plantarum BFE 5092 was sequenced and analysed. The sequence consists of 5206 bp with a mol% G + C content of 35.8%. Nine putative open reading frames were identified. A typical pC194 family double strand origin (dso) and a putative single strand origin (sso) were predicted upstream of a rep gene. This rep gene encoded a replication protein of 314 amino acids exhibiting 98% amino acid sequence identity to the Rep protein of plasmid pLAB1000 from Lactobacillus hilgardii. A mob gene encoding a mobilization protein was also identified and this protein showed high amino acid similarity to Mob proteins from various L. plantarum plasmids. Downstream of the mob gene, a second putative replication region was identified that is similar to the pMV158 family of plasmids. It contains a dso as well as a putative sso, and encodes the 52 amino acid repressor-like protein RepA, the replication initiation protein RepB of 215 amino acids, and the 48 amino acid RepC that is similar to ORFD of the lactococcal plasmid pWVO1. RT-PCR and qRT-PCR expression analyses of the rep and repB genes showed that the repB gene was expressed at a higher level. To confirm that the plasmid replicated by the rolling-circle-type mechanism, the presence of a characteristic single strand intermediate DNA was shown to be produced during replication. Plasmid copy number was ca. 30 per equivalent chromosome copy number based on qRT-PCR analyses. The plasmid also encodes four additional putative proteins of unknown function. The unusual feature of a rolling-circle plasmid having two different plasmid-encoded replication initiation proteins from different replicon families suggests that the genes for these may have originated from different plasmids.
► The cryptic plasmid pMRI 5.2 from L. plantarum BFE 5092 was completely sequenced.
► Replication was determined to be via the rolling circle mechanism.
► Plasmid copy number was determined to be approx. 30 per chromosome equivalent.
► The plasmid was unusual as it contained two replication initiation genes and origins of replication.
► The repB replication initiation gene was expressed at a higher level.
Journal: Plasmid - Volume 69, Issue 2, March 2013, Pages 160–171