Molecular characterization of plasmids pS7a and pS7b fromLactococcus lactissubsp.lactisbv. diacetylactis S50 as a base for the construction of mobilizable cloning vectors

Abstract

Aims: Strain Lactococcus lactis subsp. lactis bv. diacetylactis S50 harbours five theta‐replicating plasmids (pS6, pS7a, pS7b, pS80 and pS140). The aim of this study was to characterize domains involved in the replication and conjugative mobilization of the small plasmids pS7a and pS7b, which are structurally very similar. Methods and Results: Complete nucleotide sequences of pS7a and pS7b were determined by cloning DNA fragments of different sizes into Escherichia coli vectors. Linearized plasmids and four EcoRI fragments of the pS7a and pS7b were cloned into an origin probe vector. Constructed plasmids (pSEV10, pSK10, pISE1a and pISE1b) were able to replicate in the strain L. lactis subsp. cremoris MG1363. In addition, experiments showed that plasmids pS7a and pS7b contained oriT sequences and their conjugative transfer directly depended on the presence of pS80 in donor cells. Conclusions: Plasmids pS7a and pS7b contained typical lactococcal theta replication origin and repB gene that enable them to replicate in the strain L. lactis subsp. cremoris MG1363. Plasmid pS80 plays a key role in the conjugative transfer of small plasmids. Significance and Impact of the Study: Plasmids pS7a and pS7b‐based derivatives could be valuable tools for genetic manipulation, studying processes of plasmid maintenance and horizontal gene transfer in lactococci.

Acquisition through Horizontal Gene Transfer of Plasmid pSMA198 by Streptococcus macedonicus ACA-DC 198 Points towards the Dairy Origin of the Species

“…lactis biovar. diacetylactis S50 isolated from butter [ 42 ]. Once more, these structures are highly conserved among several lactococcal plasmids including pCI305 [ 42 , 43 ].…”

Origin-of-transfer sequences facilitate mobilisation of non-conjugative antimicrobial-resistance plasmids inStaphylococcus aureus

“…The relaxase- in trans mechanism of mobilisation has been documented for the mobilisation of non-conjugative genomic islands and cryptic chromosomal oriT sites by ICEs ( 27 ) and plasmids ( 29 , 32 ). Mobilisation of lactococcal plasmids pS7a and pS7b occurs with the help of a helper plasmid pS80, which carries a similar oriT sequence and presumably encodes a Mob protein compatible with pS7a and pS7b ( 30 ). Additionally a distinct mechanism of mobilisation has been described for Bacillus subtilis plasmids, which likely involves interactions between plasmid RCR-Rep proteins and the ICE Bs 1-encoded T4SS ( 28 ).…”

Plasmids from Food Lactic Acid Bacteria: Diversity, Similarity, and New Developments

“…Plasmids of L. lactis are involved in essential functions, e.g., bacteriocin production [ 56 , 57 , 58 , 59 ], cadmium resistance [ 60 , 61 ], antibiotic resistance [ 62 ], as well as in industrially relevant and significant characteristics, namely citrate utilization [ 63 ], casein utilization [ 55 , 64 ], lactose utilization [ 55 , 63 , 64 , 65 ], oligopeptide transport [ 63 , 65 , 66 ], orotate transport [ 67 ], cation transport [ 62 , 65 , 68 ], stress response and adaption [ 62 , 63 , 68 , 69 ], exopolysaccharide production [ 70 ], anti-phage restriction/modification systems [ 61 , 62 , 63 , 71 , 72 , 73 , 74 ], folate biosynthesis [ 65 ], proteolysis [ 65 , 75 ], and conjugal transfer [ 76 ].…”