Characterization of a novel theta-type plasmid pSM409 of Enterococcus faecium RME isolated from raw milk
| Autor: | Suranjita Mitra, Swadesh Ranjan Biswas, Bidhan Chandra Mukhopadhyay, Sukhendu Mandal, Tawsif Ahmed Kazi |
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| Rok vydání: | 2020 |
| Předmět: |
0301 basic medicine
DNA Replication DNA Bacterial Sequence analysis Enterococcus faecium Biology Origin of replication Homology (biology) 03 medical and health sciences Open Reading Frames 0302 clinical medicine Plasmid Genetics Direct repeat Animals Replicon Amino Acid Sequence Gene Bacteriocin immunity Repetitive Sequences Nucleic Acid Base Sequence General Medicine 030104 developmental biology Milk 030220 oncology & carcinogenesis Cattle Plasmids |
| Zdroj: | Gene. 777 |
| ISSN: | 1879-0038 |
| Popis: | Enterococcal plasmids have generated renewed interest for their indispensable role in pathogenesis and dissemination of multidrug-resistance. Recently, a novel plasmid pSM409 (4303-bp, GC% = 33.6%), devoid of antibiotic-resistance and virulence genes, has been identified in Enterococcus faecium RME, isolated from raw milk by us. pSM409 contains six open reading frames encoding a replication initiator protein (RepB) and five accessory proteins: antitoxin epsilon, bacteriocin immunity protein, HsdS, and two hypothetical proteins. Comparative sequence analysis of pSM409 reveals a mosaic pattern of similarity with different loci obtained from different theta plasmids, which dictates the plasmid to be heterogeneous or mosaic, possibly due to recombination. The pSM409 comprised of a typical theta-type origin of replication with four and a half direct repeats (iterons) of 22 nucleotides. The pSM409-RepB shared 76–82% homology with the RepB of reported theta plasmids from different genera, with dissimilarities mostly in its DNA-binding and C-terminal domain. The RepB sequence-based phylogenetic tree revealed its distinct position relative to the reported ones. The RepB grouped in the same clade has identical DNA-binding domains and their cognate iterons, possibly due to their sequence-specific interaction to initiate plasmid replication. Comparative analysis of the pSM409-iteron reveals that the repeats markedly differed from their closest homologues. This clade-specific relationship provides a new concept of classifying theta plasmids. The theta-type replicon identified in pSM409 has been found to be unique to E. faecium RME, prompting us to further investigate its utility as a vector for genetic manipulation of enterococci for health and industry. |
| Databáze: | OpenAIRE |
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