Humans have developed many uses for plasmids and have created software to record the DNA sequences of plasmids for use in many different techniques. They also investigated the presence of two key elements of plasmid mobility, type IV pili coupling protein (T4CP) and the ATPase VirB4 (Smillie et al., 2010). Yagi J. M., Sims D., Brettin T., Bruce D., Madsen E. L. (2009). Plasmids are so common in bacteria and archaea.. They successfully identified 160 circular sequences carrying a gene with a plasmid replication domain, and the majority of these sequences were novel (Jorgensen et al., 2014). [10] Smaller plasmids make use of the host replicative enzymes to make copies of themselves, while larger plasmids may carry genes specific for the replication of those plasmids. Irrespective of the organism the structure or the typical nature of the plasmid does not undergo any major change. Due to their artificial nature, lab plasmids are commonly referred to as vectors or constructs. To insert a gene of interest into a vector, scientists may utilize one of a variety of. When a virulence plasmid is inside a bacterium, it turns that bacterium into a pathogen, which is an agent of disease. [12], Plasmids almost always carry at least one gene. This sits in the cytoplasm of the bacterial cell.. Plasmids usually carry at least one gene, and many of the genes that plasmids carry are beneficial to their host organisms. Drives transcription of the target gene. This type of system was first found in plasmid R1. Conjugative plasmids contain a set of transfer genes which promote sexual conjugation between different cells. The ease of modifying plasmids and the ability of plasmids to self-replicate within a cell make them attractive tools for the life scientist or bioengineer. Metcalf W. W., Zhang J. K., Apolinario E., Sowers K. R., Wolfe R. S. (1997). Conjugation is one of the most effective mechanisms to spread genetic elements among bacteria (Guglielmini et al., 2011). What is a non-conjugative plasmid? In essence, this is a scaled-up miniprep followed by additional purification. Plasmids have been classified based on incompatibility since the 1970s. Jeon C. O., Park M., Ro H. S., Park W., Madsen E. L. (2006). They are mainly found in bacteria, but also exist naturally in archaea and eukaryotes such as yeast and plants. Cytoplasmic viral episomes (as in poxvirus infections) can also occur. Many of the genes carried by a plasmid are beneficial for the host cells, for example: enabling the host cell to survive in an environment that would otherwise be lethal or restrictive for growth. Toxin-antitoxin systems could prevent harmful large deletions in a bacterial genome, though arguably deletions of large coding regions are fatal to a daughter cell regardless. Small polydispersed DNAs (spcDNAs), a type of eccDNA, are commonly found in conjunction with genome instability. (2010) reported that about 14% of the full-sequenced plasmids were predicted to be conjugative. Tilly et al. It is likely that plasmids with Rep types of pDOJH10S have a broad host range in the phylum Actinobacteria. An intermediate class of plasmids are mobilizable, and carry only a subset of the genes required for transfer. sharing sensitive information, make sure youre on a federal Although A. baumannii is a ubiquitous organism, . EcDNAs could be clustered together within the nucleus, which can be referred to as ecDNA hubs. de Been M., Lanza V. F., de Toro M., Scharringa J., Dohmen W., Du Y., et al.. (2014). E. coli is found naturally in the human gut and in other animals, but certain strains of E. coli can cause severe diarrhea and vomiting. Therefore, the GC content of the plasmid is likely to be important for determining its host range. Other types of plasmids are often related to yeast cloning vectors that include: The mitochondria of many higher plants contain self-replicating, extra-chromosomal linear or circular DNA molecules which have been considered to be plasmids. The average size of these plasmids was 4.6 kb, while that of RepABC-type plasmids was 483 kb (Figure (Figure3C),3C), suggesting that the newly characterized Rep proteins may be appropriate for the replication of small plasmids. proposed an efficient method to identify each plasmid based on multiplex PCR (Bunikis et al., 2011). They may contain genes that enhance the survival of an organism, either by killing other organisms or by defending the host cell by producing toxins. Multiple plasmids can coexist in the same cell, each with different functions. The majority of the plasmids from Corynebacterineae were found in Corynebacterium (38 plasmids), Mycobacterium (29 plasmids), and Rhodococcus (31 plasmids). Incompatible plasmids (belonging to the same incompatibility group) normally share the same replication or partition mechanisms and can thus not be kept together in a single cell.[16][17]. Luo Y. R., Kang S. G., Kim S. J., Kim M. R., Li N., Lee J. H., et al.. (2012). Many plasmids have been identified from environmental samples, including the human gut, by metagenomic analyses (Elsaied et al., 2011; Kristiansson et al., 2011; Zhang et al., 2011; Brolund et al., 2013; Song et al., 2013). The cloning method is ultimately chosen based on the plasmid you want to clone into. (C) Histograms of plasmid size (left) and GC content (right) in phylum Actinobacteria. (A) Histograms of plasmid size (left) and GC content (right) of Firmicutes in each class. In addition to the chromosome, bacteria often contain plasmids . (2012). A plasmid that cannot trigger the sexual conjugation process C. A plasmid that codes for toxins that kill conjugative plasmids D. A plasmid that prevents the sexual conjugation process from occurring, 3. This type of ecDNA is commonly seen in cancer cells of various histologies, but virtually never in normal cells. hundred million. Alvarado A., Garcillan-Barcia M. P., de la Cruz F. (2012). Sequence analysis of three plasmids harboured in. After the gene of interest is inserted, the plasmids are introduced into bacteria by a process called transformation. As for the distribution of the GC content of the plasmids, both types showed a wide range of values (2374%; Figure Figure2D,2D, right), probably because various hosts harbor both mobilizable and conjugative plasmids. Methods of direct detection by PCR using degenerate primers have been reported for IncP-1, IncP-7, and IncP-9 plasmids from environmental samples (Dealtry et al., 2014) and for plasmids of different MOB families (Alvarado et al., 2012). A foreign DNA element (such as the gene for insulin) is then spliced into the plasmid. Plasmids refer to extrachromosomal free circular DNA found in the cytoplasm. A plasmid is a small circular piece of DNA found in bacterial cells, and someone new to plasmids may need some extra guidance to understand the specific components that make up a plasmid and why each is important. However, this code is quite universal and is slightly different in mitochondrial DNA of fungi, animals, protists and plants. Xiong J., Alexander D. C., Ma J. H., Deraspe M., Low D. E., Jamieson F. B., et al.. (2013). [10] Among the 4602 plasmids in the database, 137 plasmids were found in Archaea: 112 plasmids were in Euryarcheoata (Figure (Figure1A)1A) and 23 plasmids were in Crenarchaeota. Arnold H. P., She Q., Phan H., Stedman K., Prangishvili D., Holz I., et al.. (1999). In a bacterium, different plasmids can only co-occur if they are compatible with each other. Guglielmetti S., Mora D., Parini C. (2007). Approximately half of the plasmids in class Rhodosprillales were found in Acetobacter (60 of 122 plasmids; Table S1). When an F+ bacterium conjugates with an F bacterium, two F+ bacterium result. Control of ColE1 plasmid replication by antisense RNA. Kristiansson E., Fick J., Janzon A., Grabic R., Rutgersson C., Weijdegrd B., et al.. (2011). The pNOB8-type plasmids are larger in size (around 30 kb) than pRN-type plasmids (less than 10 kb) and are known to be conjugative (She et al., 1998). A unique feature of Borrelia is its segmented genome consisting of multiple circular and linear plasmids in addition to its linear chromosome within a single cell (Casjens et al., 2000). Royal Society of Chemistry Publishing - Why do plasmids manipulate the expression of bacterial phenotypes? Thus, all of the bacteria are placed on an antibiotic plate to select for ones that took up a plasmid. Resistance or R plasmids contain genes that help a bacterial cell defend against environmental factors such as poisons or antibiotics. Bethesda, MD 20894, Web Policies The transmission of antibiotic resistance to Enterococcus is mediated by the pheromone-responsiveness and broad host range of Inc18 group plasmids (Palmer et al., 2010). [5], Mitochondrial DNA can play a role in the onset of disease in a variety of ways. Most plants inherit mtDNA maternally with one noted exception being the redwood Sequoia sempervirens that inherit mtDNA paternally. More than 90% of the plasmids in the database were identified in 22 phyla: Proteobacteria (2142 sequences, 47%), Firmicutes (1129 sequences, 25%), Spirochaetes (423 sequences, 9.2%), Actinobacteria (269 sequences, 5.8%), Cyanobacteria (136 sequences, 3.0%) Bacteroidetes (74 sequences, 1.6%), Chlamydiae (67 sequences, 1.5%), and Tenericutes (62 sequences, 1.3%; Figure Figure1A).1A). Some Col factors and R factors can transfer themselves from one cell to another and thus are capable of spreading rapidly through a bacterial population. The average size of the 4602 plasmids (79.8 kb) was larger than those of 1730 plasmids (63.5 kb). Some episomes, such as herpesviruses, replicate in a rolling circle mechanism, similar to bacteriophages (bacterial phage viruses). Most plasmids are double-stranded circular DNA molecules, but few linear plasmids have been identified in Borrelia, Streptomyces, and some Proteobacteria. Culture-independent methods have recently been developed to isolate and identify novel types of plasmids and to detect plasmid transfers (Heuer and Smalla, 2012). Torres M. J., Rubia M. I., Bedmar E. J., Delgado M. J. [12] Low-copy-number plasmids that exist only as one or a few copies in each bacterium are, upon cell division, in danger of being lost in one of the segregating bacteria. [52][7][53], ecDNA is responsible for a large number of the more advanced and most serious cancers, as well as for the resistance to anti-cancer drugs.[54]. A method for purifying high quality and high yield plasmid DNA for metagenomic and deep sequencing approaches. [10], In order for plasmids to replicate independently within a cell, they must possess a stretch of DNA that can act as an origin of replication. This method enables researchers to search for plasmids in a wider microcosm containing the uncultivated microbial fraction (Heuer et al., 2012). Two plasmids were found to share >83% identity with the sequence of the Rep protein from pOZ176: pPNAP01, a plasmid of Polaromonas naphthalenivorans CJ2, encodes proteins involved in the degradation of naphthalene (Jeon et al., 2003, 2006; Yagi et al., 2009), and pBB1 (GenBank/EMBL/DDBJ accession no. Plasmid replication control by antisense RNA. Taken together, these findings suggest that the nucleotide sequences of the replication systems used by previously-known Inc group plasmids could be important tools for classifying other plasmids. Theyare mainly found in bacteria, but also exist naturally in archaea and eukaryotes such as yeast and plants. Fluorescence in situ hybridization (FISH) using specific probes targeting 16S rRNA sequences and in situ PCR in transconjugant cells are able to detect transconjugants at the single-cell level (Amann and Fuchs, 2008; Cenciarini-Borde et al., 2009; Wagner and Haider, 2012). Of the 4602 plasmids included in our analysis, 388 plasmids could be classified using the 26 Rep families, and 383 of them were found in Firmicutes (Table S1). The average size of the pUT-type plasmids was 68.4 kb, which was larger than Rep20 type plasmids and smaller than RepABC-type plasmids (Figure (Figure3C).3C). Understanding the recognition pathways has implications towards prevention and treatment of diseases. A plasmid is a small circular DNA molecule found in bacteria and some other microscopic organisms. A classification system for plasmids from enterococci and other Gram-positive bacteria. According to the Pseudomonas genome database (http://www.pseudomonas.com/), the GC contents of Pseudomonas aeruginosa ranged from 66.1 to 66.6% (average GC contents = 66.4%). Straley S. C., Plano G. V., Skrzypek E., Haddix P. L., Fields K. A. Gene amplifications in cancer are often on extrachromosomal, circular elements. Fertility plasmids, also known as F-plasmids, contain transfer genes that allow genes to be transferred from one bacteria to another through conjugation. [21] In multicellular animals, including humans, the circular mtDNA chromosome contains 13 genes that encode proteins that are part of the electron transport chain and 24 genes for Other mitochondrial proteins; these genes are broken down into 2 rRNA genes and 22 tRNA genes. [36] The function of eccDNA have not been widely studied, but it has been proposed that the production of eccDNA elements from genomic DNA sequences add to the plasticity of the eukaryotic genome and can influence genome stability, cell aging and the evolution of chromosomes.[37]. Based on the hypothesis, the relationships of GC contents between the plasmid and the host genome might be also important for predicting when the plasmid was introduced into the host species. McLeod M. P., Warren R. L., Hsiao W. W., Araki N., Myhre M., Fernandes C., et al.. (2006). Several cancer viruses, including Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus, are maintained as latent, chromosomally distinct episomes in cancer cells, where the viruses express oncogenes that promote cancer cell proliferation. The distribution of classified plasmids is shown in beige (pBL1 family), spring green (pCG1/pNG2 family), yellow (pMSC262 family), brown (plasmids with TapR1, TpgR1 Tac, and/or Tpc), light brown (pDOJH10S-type), and gray (IncP-1 plasmids), black (other Rep types), and white (unclassified plasmids). Plasmids are well suited to genetic engineering in other ways. Which is NOT one of the five main types of plasmids? These include a gene that confers resistance to particular antibiotics (ampicillin is most frequently used for bacterial strains), an origin of replication to allow the bacterial cells to replicate the plasmid DNA, and a suitable site for cloning (referred to as a multiple cloning site). Bacteriocins are found in many types of bacteria including E. coli, which gets them from the plasmid ColE1. Liu M. A., Kwong S. M., Jensen S. O., Brzoska A. J., Firth N. (2013). Yamashita et al. These linear plasmids require specialized mechanisms to replicate their ends. Specialized tools exist that allow ecDNA to be identified, such as, Viral DNA are an example of extrachromosomal DNA. Recently, the type bacterium that causes the sexually transmitted infection gonorrhea has become so resistant to a class of antibiotics called quinolones that a new class of antibiotics, called cephalosporins, has started to be recommended by the World Health Organization instead. (2009, 2011) and Smillie et al. However, plasmids, like viruses, are not generally classified as life. FOIA If you have a question about a specific plasmid element that you would like answered or any topic suggestions for our Plasmids 101 series, please let us know in the comments. There are five main classes: Plasmids can belong to more than one of these functional groups. Of these, 101 plasmids were classified into the RepABC type group (Table S1). Plasmids conferring resistance and virulence to Bacilli, including Enterococcus (Bacilliales) and Staphylococcus (Lactobacilliales), are causative agents of hospital infection outbreaks. Talking Glossary of Genomic and Genetic Terms. Such events are frequently triggered by the transposition of mobile elements or by the presence of unstable elements such as non-canonical (non-B) structures. Several insights into the mechanisms of replication and conjugative transfer used by plasmids are summarized first, followed by a description of the features of representative plasmids in several phyla. In the latter, much larger volumes of bacterial suspension are grown from which a maxi-prep can be performed. Start the replication process with their transfer genes B. Dijkshoorn L., Nemec A., Seifert H. (2007). This is a cheap and easy way of mass-producing the protein the gene codes for, for example, insulin. Daughter cells that retain a copy of the plasmid survive, while a daughter cell that fails to inherit the plasmid dies or suffers a reduced growth-rate because of the lingering poison from the parent cell. Some of the many things that plasmids can be used to do include: Addgene has compiled various educational resources to facilitate plasmid use in the lab. Conception Some plasmids can exist in single stranded form as intermediaries of their replication cycle or can be the replicative forms or the prophage state of some phages. [10] Plasmids can also provide bacteria with the ability to fix nitrogen. The phylum Actinobacteria includes a wide variety of bacteria with different morphologies, physiologies, and metabolic properties, and they have various kinds of plasmids (Ventura et al., 2007). [3][8] The most commonly amplified oncogenes in cancer are found on ecDNA and have been shown to be highly dynamic, re-integrating into non-native chromosomes as homogeneous staining regions (HSRs)[51][3] and altering copy numbers and composition in response to various drug treatments. Multiplex PCR as a tool for validating plasmid content of. More genomic information will be necessary for understanding the genetic evolution of these plasmids and their host chromosome. Jensen S. O., Apisiridej S., Kwong S. M., Yang Y. H., Skurray R. A., Firth N. (2010b). The antibiotic resistance gene allows for selection in bacteria. The Rep20 replication initiator from the pAG20 plasmid of, Terminal proteins essential for the replication of linear plasmids and chromosomes in, Recruitment of terminal protein to the ends of. Minimally, lab-created plasmids have an origin of replication, selection marker, and cloning site. Taton A., Unglaub F., Wright N. E., Zeng W. Y., Paz-Yepes J., Brahamsha B., et al.. (2014). Fluorescent cells are also detectable and separable with the use of flow cytometry or a micromanipulator at the single cell level; both methods have a strong potential to identify actual host ranges of plasmids (Musovic et al., 2010; Shintani et al., 2014a). Here, the Hok (Host-Killing) protein is not translated as long as the Sok antisense RNA is present. However, this classification is not appropriate for non-transmissible plasmids. Several shuttle vectors are available for certain genera within Euryarcheoata, such as halophiles (Haloarcula), methanogens (Methaonococcus and Methonosarcina), and Thermococcales (Pyrococcus). Garcilln-Barcia et al. Their 143 plasmids are characterized by a highly variable plasmid number (from 0 to 11) and size (from 150 to 1683 kb). Stillwell L. C., Thurston S. J., Schneider R. P., Romine M. F., Fredrickson J. K., Saffer J. D. (1995). Cesareni G., Helmer-Citterich M., Castagnoli L. (1991). A subset of 158 plasmids classified into Inc1 to Inc18 groups was found in Lactobacillales, including Enterococcus (36 plasmids), Lactobacilllus (56 plasmids), Lactococcus (15 plasmids), and Streptococcus (34 plasmids; Table S1). [26], Eukaryotic chloroplasts, as well as the other plant plastids, also contain extrachromosomal DNA molecules. Michelle R. McGehee, in Molecular Biology (Third Edition), 2019 2 General Properties of Plasmids Plasmids are usually circular molecules of DNA, although occasionally, plasmids that are linear or made of RNA exist. Omissions? (2005). Allows for selection of plasmid-containing bacteria. Although the IncP-1 to IncP-14 groups have been found in Pseudomonas, only 21 plasmids in the order Pseudomonadales were classified into these groups; the other 93 plasmids classified into these Inc groups were in other orders (including Enterobacteriales and Thiotrichales), other classes (including Alphaproteobacteria and Betaproteobacteria), or even other phyla (including Actinobacteria and Thermotogae; Table S1). Within this phylum, 1077 plasmids were classified using previously known Rep proteins. Euryarcheoata includes all methanogens, haloarchaea, and some hyperthermophilic genera such as Pyrococcus and Thermococcus. Plasmids are used in the techniques and research of genetic engineering and gene therapy by gene transfer to bacterial cells or to cells of superior organisms, whether other plants, animals, or other living organisms, to improve their resistance to diseases or to improve their growth rates or to improve any other required traits. A positive association between increased mtDNA levels and an increased risk for developing kidney tumors has been observed but there does not appear to be a link between mtDNA levels and the development of stomach cancer. Indeed, even in the identical host species, the ranges of GC contents of plasmids were wider than those of the host genome sequence. This review summarizes the current situation of the classification of fully sequenced plasmids based on their host taxonomy and their features of replication and conjugative transfer. [45] For this reason, organelle DNA, including mtDNA, is inherited from the mother. This results in relatively large amounts (several hundred micrograms) of very pure plasmid DNA. [49], Gene amplification is among the most common mechanisms of oncogene activation. [3] The ecDNA notation encompasses all forms of the large, oncogene-containing, extrachromosomal DNA found in cancer cells. Wang J., Stephan R., Karczmarczyk M., Yan Q., Hachler H., Fanning S. (2013). Such plasmids are in fact common among fungi and higher plants. The bacterium Escherichia coli (E. coli) has several virulence plasmids. Expansion of a plasmid classification system for Gram-positive bacteria and determination of the diversity of plasmids in. Acinetobacter baumannii is known to be an important pathogen, and the plasmids in the genus Acinetobacter are considered to be key genetic factors in the spread of multi-drug resistance (Dijkshoorn et al., 2007; Evans and Amyes, 2014). This method has also facilitated the successful identification of several novel types of plasmids (Jones and Marchesi, 2007; Zhang et al., 2011; Burmolle et al., 2012). A plasmid that is attached to the cell membrane or integrated into the bacterial chromosome is called an episome ( q.v. carried out a plasmidome network analysis of all available complete bacterial plasmids to identify and characterize the most recent horizontal gene transfer or plasmid transfer (Yamashita et al., 2014). Accessibility [5] The fact that this organelle contains its own DNA supports the hypothesis that mitochondria originated as bacterial cells engulfed by ancestral eukaryotic cells. Structure of 2 plasmid found in yeast. ecDNA are much larger than eccDNA, and are visible by light microscopy. In this case, researchers grow bacteria containing a plasmid harboring the gene of interest. Pinto U. M., Pappas K. M., Winans S. C. (2012). The use, distribution or reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. The plasmids in Actinobacteria were large and had high GC contents (Figures 1B,C). These pieces of DNA are important because they can confer special abilities to the cell, such as antibiotic resistance or the ability to break down complex sugars. Additionally, plasmids are being investigated as a way to transfer genes into human cells as part of gene therapy. These elements carry core genes and have codon usage similar to the chromosome, yet use a plasmid-type replication mechanism such as the low copy number RepABC. Their transfers are induced by pheromones generated from lipoprotein signal peptides encoded on the host chromosome (Clewell, 2007; Dunny, 2007). and transmitted securely. In this review, known plasmids for which the complete sequence was available were classified by their host and their (putative) replication or transfer systems. However, many plasmids also have selectable markers for use in other cell types. The diversity of conjugative relaxases and its application in plasmid classification. Several rolling-circle replication plasmids were found in C. glutamicum, and the pBL1 (including pAG3 and pCG2) and pCG1 (including pCG4 and pGA2) families were proposed (Tauch et al., 2003a). Degradative plasmids, which enable the digestion of unusual substances, e.g. Sok RNA decays relatively rapidly. Mobile genetic elements (MGEs) carrying catabolic genes, Management of Microbial Resources in the Environment. IncW plasmids were found in many bacterial sources in the 1980s. Guglielmini J., Quintais L., Garcilln-Barcia M. P., de la Cruz F., Rocha E. P. (2011). [22] The number of mtDNA molecules per mitochondrion varies from species to species, as well as between cells with different energy demands. Structure and Functions of Bacterial Plasmid. Mobile genetic elements: the agents of open source evolution, Regulation of bacterial conjugation: balancing opportunity with adversity. [16][17], The long, linear "borgs" that co-occur with a species of archaeon which may host them and shares many of their genes could be an unknown form of extrachromosomal DNA structures. There are several methods to isolate plasmid DNA from bacteria, ranging from the miniprep to the maxiprep or bulkprep. This was probably because the sizes of the plasmids are closely related to their replication systems. Plants also show uniparental mtDNA inheritance. Structure, function, and evolution of linear replicons in. The distribution of plasmid size was bimodal, and the 269 putative rolling-circle replication plasmids had a smaller average size (5713 bp), while the average size of the 200 theta-type replication plasmids was larger (45,498 bp; Figure Figure4B,4B, left). Different TLRs in human detect different PAMPS: lipopolysaccharides by TLR4, viral dsRNA by TLR3, viral ssRNA by TLR7/TLR8, viral or bacterial unmethylated DNA by TLR9. Other plasmids found were IncB/O/K/Z, IncR, IncN and P0111 as well as some plasmids containing mainly phage like genes (phage/phage plasmid) (8 out of 42 plasmids). Enter your email address to receive updates about the latest advances in genomics research. Plasmids in Streptomycieae are found in Streptomyces species, and several of them are large linear plasmids. "[9] The term's early usage included any bacterial genetic material that exists extrachromosomally for at least part of its replication cycle, but because that description includes bacterial viruses, the notion of plasmid was refined over time to comprise genetic elements that reproduce autonomously. Ainsworth S., Stockdale S., Bottacini F., Mahony J., van Sinderen D. (2014). Sometimes called EEs, extrachromosomal elements, have been associated with genomic instability in eukaryotes. Seto M., Kimbara K., Shimura M., Hatta T., Fukuda M., Yano K. (1995). Smillie et al. Any newcomer who joins a molecular biology lab will undoubtedly be asked to design, modify, or construct a plasmid. The gene to be replicated is normally inserted into a plasmid that typically contains a number of features for their use. Genetic tools used in the analysis of archaea are currently being developed. Each bacterium with a plasmid gives rise to a cluster of identical, plasmid-containing bacteria called a colony. A plasmid is a small, circular piece of DNA that is different than the chromosomal DNA, which is all the genetic material found in an organism's chromosomes. Extrachromosomal DNA (ecDNA) found in cancer have historically been referred to as Double minute chromosomes (DMs), which present as paired chromatin bodies under light microscopy. This plasmid carries genes required for survival of its host, including the resT gene, which encodes a telomere resolvase involved in the resolution of the replicated telomeres of the linear chromosome and plasmids in B. burgdorferi (Tilly et al., 2012).