Analysis of a region from the bacteriophage resistance plasmid pCI528 involved in its conjugative mobilization between Lactococcus strains

Lucey, Mary Catherine; Daly, Charles; Fitzgerald, Gerald F.

doi:10.1128/jb.175.18.6002-6009.1993

Cited by 19 publications

(12 citation statements)

References 53 publications

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“…However, no gene encoding conjugative function was present in pGdh442, indicating that pGdh442 is not self-transmissible but rather is mobilizable by the sex factor of MG1363 that encodes conjugative functions (Gasson et al, 1995), as reported elsewhere for many L. lactis plasmids (Lucey et al, 1993).…”

Section: Plasmid Mobilizationmentioning

confidence: 80%

Sequence analysis of the mobilizable lactococcal plasmid pGdh442 encoding glutamate dehydrogenase activity

2007

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A novel plasmid named pGdh442 had previously been isolated from a plant Lactococcus lactis strain. This plasmid encodes two interesting properties with applications in the dairy industry: a glutamate dehydrogenase activity that stimulates amino acid conversion to aroma compounds, and cadmium/zinc resistance that can be used as a selectable marker. Moreover, this plasmid can be transferred naturally to other strains, but appears to be incompatible with certain other lactococcal plasmids. During this study, the complete sequence of pGdh442 (68 319 bp) was determined and analysed. This plasmid contains 67 ORFs that include 20 IS elements that may have mediated transfer events between L. lactis and other genera living in the same biotope, such as Streptococcus, Pediococcus and Lactobacillus. Even though it is a low-copy-number plasmid, it is relatively stable due to a theta replication mode and the presence of two genes involved in its maintenance system. However, pGdh442 is incompatible with pSK08-derived protease/lactose plasmids because both possess the same replication and partition system. pGdh442 is not self-transmissible, but can be naturally transmitted via mobilization by conjugative elements carried by the chromosome or by other plasmids, such as the 712-type sex factor, which is widely distributed in L. lactis. In addition to several genes already found on other L. lactis plasmids, such as the oligopeptide transport and utilization genes, pGdh442 also carries several genes not yet identified in L. lactis. Finally, it does not carry genes that would trigger concern over its presence in human food. INTRODUCTIONLactococcus lactis is a lactic acid bacterium (LAB) widely used as a starter culture for the production of various fermented dairy products. Although this bacterium is commonly found in milk, it is also naturally present on plants and on parts of the bodies of cows (Nomura et al., 2006;Salama et al., 1995;Teuber, 1995). Typically, Lactococcus strains possess an abundance of plasmid DNA. Many large L. lactis plasmids are self-transmissible or mobilizable by conjugative elements carried by the chromosome or plasmids of the host strain (Gasson et al., 1995). Through their natural transfer, these plasmids increase the probability of the gene moving between bacteria, and enable strains to acquire a wide variety of new genetic traits. They thus endow their hosts with many traits which offer a selective advantage to colonize specific biotopes. For example, the majority of dairy strains have adapted to growth in milk by acquiring plasmids that encode lactose catabolism (De Vos & Gasson, 1989), casein degradation (Kok, 1990), citrate utilization (Kempler & McKay, 1979) and oligopeptide transport (Yu et al., 1996). In addition, strains isolated from plant and animal environments, which contain a wide variety of cytotoxic compounds, have developed appropriate protection mechanisms (Putman et al., 2000), such as multidrug resistance, nisin resistance and heavy metal resistance (Dougherty et al., 1998;Liu et al.,...

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Section: Plasmid Mobilizationmentioning

confidence: 80%

Sequence analysis of the mobilizable lactococcal plasmid pGdh442 encoding glutamate dehydrogenase activity

2007

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“…Indeed, we have recently found that another conjugative plasmid, pCBG104 (10), encoding an undefined conjugative transfer system, is capable of mobilizing pRH001 (R. M. Hickey, D. P. Twomey, R. P. Ross, and C. Hill, unpublished work). However, in contrast to the oriT loci of pCI528 and pRS01, which can be mobilized by the ML3/712 class sex factor (33,38), the pMRC01 oriT is apparently not mobilized by this element. This inability to mobilize the pMRC01 oriT may be a reflection of inherent differences in the secondary structure of this element.…”

Section: ϫ4mentioning

confidence: 96%

“…1C). A similar sequence is also present in the self-transmissible conjugative lactococcal plasmids pRS01 (38) and pCI528 (33) and in several lactococcal plasmids, including pAH33 (41), pNZ4000 (48), pSRQ900 (16), pBL1 (34), and pWV01 (three copies present; 30). Plasmids from other lactic acid bacteria, such as the Lactobacillus plantarum phage resistance plasmid pLKS (15), the Lactobacillus helveticus cryptic plasmid pLH2 (43), and the Leuconostoc mesenteroides plasmid pTXL1 (accession no.…”

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confidence: 99%

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Exploitation of Plasmid pMRC01 To Direct Transfer of Mobilizable Plasmids into Commercial Lactococcal Starter Strains

Hickey

Twomey

Ross

et al. 2001

Appl Environ Microbiol

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Genetic analysis of the 60.2-kb lactococcal plasmid pMRC01 revealed a 19.6-kb region which includes putative genes for conjugal transfer of the plasmid and a sequence resembling an origin of transfer (oriT). This oriT-like sequence was amplified and cloned on a 312-bp segment into pCI372, allowing the resultant plasmid, pRH001, to be mobilized at a frequency of 3.4 ؋ 10 ؊4 transconjugants/donor cell from an MG1363 (recA mutant) host containing pMRC01. All of the resultant chloramphenicol-resistant transconjugants contained both pRH001 and genetic determinants responsible for bacteriocin production and immunity of pMRC01. This result is expected, given that transconjugants lacking the lacticin 3147 immunity determinants (on pMRC01) would be killed by bacteriocin produced by the donor cells. Indeed, incorporation of proteinase K in the mating mixture resulted in the isolation of transformants, of which 47% were bacteriocin deficient. Using such an approach, the oriT-containing fragment was exploited to mobilize pRH001 alone to a number of lactococcal hosts. These results demonstrate that oriT of pMRC01 has the potential to be used in the development of mobilizable food-grade vectors for the genetic enhancement of lactococcal starter strains, some of which may be difficult to transform.

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“…Self-transmissible conjugative plasmids have the ability to form effective cell-to-cell contact, while mobilization plasmids are only able to prepare their DNA for transfer (Steele and McKay 1989). In contrast, nonself-transferable plasmids contain only a cis-acting transfer origin (oriT) and mobA gene, while other conjugal functions have to be provided in trans from true conjugative plasmid or a chromosomally located sex factor (Lucey et al 1993;Lanka and Wilkins 1995). Conjugation has proven to be a useful gene transfer system for the genetic analysis of lactococci (Gasson 1990).…”

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confidence: 99%

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

Strahinić¹,

Kojić²,

Tolinački

et al. 2009

Journal of Applied Microbiology

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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.

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Analysis of a region from the bacteriophage resistance plasmid pCI528 involved in its conjugative mobilization between Lactococcus strains

Cited by 19 publications

References 53 publications

Sequence analysis of the mobilizable lactococcal plasmid pGdh442 encoding glutamate dehydrogenase activity

Sequence analysis of the mobilizable lactococcal plasmid pGdh442 encoding glutamate dehydrogenase activity

Exploitation of Plasmid pMRC01 To Direct Transfer of Mobilizable Plasmids into Commercial Lactococcal Starter Strains

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

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