Characterization of the Genome of a Rod-shaped Virus Infecting Spiroplasma citri

Dickinson, Matthew; Townsend, R.

doi:10.1099/0022-1317-65-9-1607

Cited by 21 publications

(6 citation statements)

References 15 publications

(12 reference statements)

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“…Plectroviruses with homologous genes of S . citri plectroviruses (Sha et al 2000) and a similar replication mechanism (Dickinson and Townsend 1984) were isolated from Acholeplasma (Gourlay and Wyld 1973; Steinick et al 1980), another insect/plant-associated Mollicutes genus distantly related to spiroplasmas (fig. 1).…”

Section: Resultsmentioning

confidence: 99%

“…However, the range of genome sizes (6.8 kb [Sha et al 2000] to 8.5 kb [Dickinson and Townsend 1984]) and nonconservation in gene contents of plectroviruses (Sha et al 2000) do suggest they may carry bacterial DNA through imprecise excision of prophage genome from the host chromosome. Furthermore, plectroviruses may be able to invade different strains or even different species of the Citri clade, as indicated by the experimental infection of various S .…”

Section: Resultsmentioning

confidence: 99%

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Complete Genomes of Two Dipteran-Associated Spiroplasmas Provided Insights into the Origin, Dynamics, and Impacts of Viral Invasion in Spiroplasma

Chen

et al. 2013

Genome Biology and Evolution

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Spiroplasma is a genus of wall-less, low-GC, Gram-positive bacteria with helical morphology. As commensals or pathogens of plants, insects, ticks, or crustaceans, they are closely related with mycoplasmas and form a monophyletic group (Spiroplasma–Entomoplasmataceae–Mycoides) with Mycoplasma mycoides and its relatives. In this study, we report the complete genome sequences of Spiroplasma chrysopicola and S. syrphidicola from the Chrysopicola clade. These species form the sister group to the Citri clade, which includes several well-known pathogenic spiroplasmas. Surprisingly, these two newly available genomes from the Chrysopicola clade contain no plectroviral genes, which were found to be highly repetitive in the previously sequenced genomes from the Citri clade. Based on the genome alignment and patterns of GC-skew, these two Chrysopicola genomes appear to be relatively stable, rather than being highly rearranged as those from the Citri clade. Phylogenetic analyses suggest that the susceptibility to plectroviral invasion probably originated in the common ancestor of the Citri clade or one of its subclades. This susceptibility may be attributed to the absence of antiviral systems found in the Chrysopicola clade. Using the virus-free genomes of the Chrysopicola clade as references, we inferred the putative viral integration sites in the Citri genomes. Comparisons of syntenic regions suggest that the extensive viral invasion in the Citri clade promoted genome rearrangements and expansions. More importantly, the viral invasion may have facilitated horizontal gene transfers that contributed to adaptation in the Citri clade.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Complete Genomes of Two Dipteran-Associated Spiroplasmas Provided Insights into the Origin, Dynamics, and Impacts of Viral Invasion in Spiroplasma

Chen

et al. 2013

Genome Biology and Evolution

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“…5 Davis, 1977, and B. C. Kirkpatrick, unpublished results). In addition to dsDNA viral replicative forms, viral ssDNA has been described for some strains of S. citri (8). Such ssDNA is readily degraded by treatment with S1 nuclease.…”

Section: Resultsmentioning

confidence: 99%

“…Plasmid DNA from Spiroplasma (2,3,24,25,29,(33)(34)(35) and Mycoplasma (4,40) species has been described. In addition, double-stranded (ds) and single-stranded (ss) DNA associated with spiroplasma, mycoplasma, and acholeplasma viruses have been described (8,21,34). The mollicute plasmids characterized to date are cryptic, and transfer of plasmid DNA between Mollicutes has not yet been demonstrated (34).…”

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confidence: 99%

Identification and characterization of plasmids from the western aster yellows mycoplasmalike organism

Kuske

Kirkpatrick

1990

J Bacteriol

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Supercoiled double-stranded DNA molecules (plasmids) were isolated from plants infected with three laboratory strains of western aster yeiows mycoplasma-like organism (AY-MLO) by using cesium chlorideethidium bromide density gradients. Southern blot analysis, using plasmids from the severe strain of AY-MLO (SAY-MLO) Plant pathogenic mycoplasma-like organisms (MLOs) cause disease in a large number of higher plants (5,23). MLOs inhabit the phloem sieve elements of plants and are transmitted between plants by phloem-feeding insects (37). MLOs multiply in both plant and insect hosts (27). MLOs resemble culturable members of the genus Mycoplasma (class Mollicutes) in morphology and antibiotic sensitivity (22), but because they have not yet been successfully cultured in vitro they have remained largely unclassified. Very little is known about their genetic composition or the mechanisms by which they cause disease.The presence of extrachromosomal DNA in the Mollicutes is well established (10,21,34). Plasmid DNA from Spiroplasma (2,3,24,25,29,[33][34][35] and Mycoplasma (4, 40) species has been described. In addition, double-stranded (ds) and single-stranded (ss) DNA associated with spiroplasma, mycoplasma, and acholeplasma viruses have been described (8,21,34). The mollicute plasmids characterized to date are cryptic, and transfer of plasmid DNA between Mollicutes has not yet been demonstrated (34).Plasmid-borne genes are important in determining pathogenicity and virulence in several plant-pathogenic bacteria (6, 31). The possibility that plant-pathogenic MLOs possess plasmid DNA with the potential to affect MLO pathogenicity prompted the present investigation. We describe here the isolation and characterization of plasmids present in laboratory and field isolates of the western aster yellows MLO (AY-MLO). Isolation of DNA from plants and leafhoppers. Symptomatic shoot apices, leaf petioles, and midribs were cut into small pieces and ground in cold mortars in PS buffer (7) without fructose. Ground tissues were filtered through Miracloth (Behring Diagnostics), and the filtrate was centrifuged at 17,500 x g for 30 min at 4°C. The pellet was suspended in Tris-EDTA buffer (15 mM Tris, 3 mM EDTA, pH 8) containing 1% sodium dodecyl sulfate (SDS), incubated on ice for 10 min, and centrifuged at 9,260 x g for 5 min at 4°C. The clarified supernatant was extracted with an equal volume of neutralized phenol followed by chloroform-isoamyl alcohol (24:1, vol/vol), and the nucleic acids were ethanol precipitated (20). Chilled, live, or frozen leafhoppers were chopped in PS buffer and macerated in a tissue homogenizer. The extract was centrifuged, and DNA was isolated as described above. MATERIALS AND METHODSDNA isolation from spiroplasmas. Spiroplasma citri (Maroc isolate) and Spiroplasma kunkelii (California isolate 245) were cultured in a modified MlA medium (17). Cells were harvested by centrifugation, washed in cold phosphatebuffered saline, and centrifuged again. The pellet was sus-1628 on May 11, 2018 by guest

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“…In the studies described in the preceding paragraph, the resistant spiroplasma strains had been derived from strains that produced the virus being investigated or a closely related virus (2,6). As a result, the genomes of these resistant spiroplasma strains already contained complete (2) or partial (6) copies of the viral genomes, a fact that complicates the interpretation of results.…”

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confidence: 99%

Resistance of Spiroplasma citri Lines to the Virus SVTS2 Is Associated with Integration of Viral DNA Sequences into Host Chromosomal and Extrachromosomal DNA

Sha¹,

Melcher²,

Davis³

et al. 1995

Appl Environ Microbiol

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Spiroplasmavirus SVTS2, isolated from Spiroplasma melliferum TS2, produces plaques when inoculated onto lawns of Spiroplasma citri M200H, a derivative of the type strain Maroc R8A2. S. citri strains MR2 and MR3, originally selected as colonies growing within plaques on a lawn of M200H inoculated with SVTS2, were resistant to SVTS2. Genomic DNA fingerprints and electrophoretic protein profiles of M200H, MR2, and MR3 were similar, but three proteins present in M200H were missing or significantly reduced in both resistant lines. None of these three polypeptides reacted with antiserum against S. citri membrane proteins, indicating that they probably are not surface-located virus receptors. Electroporation with SVTS2 DNA produced 1.5 ؋ 10 5 transfectants per g of DNA in M200H but none in MR2 or MR3, suggesting that resistance may result from inhibition of viral replication. The digestion patterns of the extrachromosomal double-stranded (ds) DNA of these lines were similar. Three TaqI fragments of MR2 extrachromosomal DNA that were not present in M200H extrachromosomal DNA hybridized strongly to an SVTS2 probe, and two of these fragments plus an additional one hybridized with the MR3 extrachromosomal DNA, indicating that a fragment of SVTS2 DNA was present in the extrachromosomal ds DNA of MR2 and MR3 but not of M200H. When the restricted genomes of all three lines were probed with SVTS2 DNA, strong hybridization to two EcoRI fragments of chromosomal MR2 and MR3 DNA but not M200H DNA indicated that SVTS2 DNA had integrated into the genomes of MR2 and MR3 but not of M200H. When MR3 extrachromosomal ds DNA containing a 2.1-kb SVTS2 DNA fragment was transfected into M200H, the transformed spiroplasmas were resistant to SVTS2. These results suggest that SVTS2 DNA fragments, possibly integrated into the chromosomal or extrachromosomal DNA of a previously susceptible spiroplasma, may function as viral incompatibility elements, providing resistance to superinfection by SVTS2.

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Characterization of the Genome of a Rod-shaped Virus Infecting Spiroplasma citri

Cited by 21 publications

References 15 publications

Complete Genomes of Two Dipteran-Associated Spiroplasmas Provided Insights into the Origin, Dynamics, and Impacts of Viral Invasion in Spiroplasma

Complete Genomes of Two Dipteran-Associated Spiroplasmas Provided Insights into the Origin, Dynamics, and Impacts of Viral Invasion in Spiroplasma

Identification and characterization of plasmids from the western aster yellows mycoplasmalike organism

Resistance of Spiroplasma citri Lines to the Virus SVTS2 Is Associated with Integration of Viral DNA Sequences into Host Chromosomal and Extrachromosomal DNA

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