Structure of the Maize Streak Virus Geminate Particle

Zhang, Wei; Olson, Norman H.; Baker, Timothy S.; Faulkner, Lee; Agbandje‐McKenna, Mavis; Boulton, Margaret I.; Davies, Jeffrey W.; McKenna, Robert

doi:10.1006/viro.2000.0739

Cited by 184 publications

(134 citation statements)

References 33 publications

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“…A pH of 8.0 has also been chosen for ACMV purification for cryo-EM (Böttcher et al, 2004) under the assumption that this pH is close to that of phloem sap and insect gut (Fife & Frampton, 1936;Hocking, 1980). In contrast, the structure of maize streak virus (MSV), which belongs to the genus Mastrevirus, was determined from a preparation purified at pH 4.8 (Zhang et al, 2001). So far, only one systematic investigation of the pH-dependent stability of geminiviruses has been accomplished (Matyis et al, 1975).…”

Section: Introductionmentioning

confidence: 99%

Disassembly of African cassava mosaic virus

Kittelmann

Jeske

2008

Journal of General Virology

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The plant-infecting geminiviruses encapsidate their single-stranded DNA genome in characteristic twinned particles that are unique among viruses. These particles are formed by joining two incomplete T51 icosahedra. African cassava mosaic virions were purified by densitygradient centrifugation from infected Nicotiana benthamiana plants and analysed for their stability with respect to pH changes and heat treatment by using electron microscopy. Negative staining and rotary shadowing revealed stable virions as well as isolated capsomeres between pH 4.0 and 8.5. At pH 9.0 and above, particles disintegrated, whereas they mainly aggregated at a pH below 6.0. Heating the preparations to 55 6C and above resulted in the complete loss of any discernible structure. A low proportion (approx. 10 %) of particles ejected their DNA within the pH range of 6.0-8.5. Most virions released their DNA at the top (15.9 %) or the shoulder (71.4 %) of the twin particles and only 12.7 % at the waist. Compared with the expected numbers of pentameric capsomeres at the top (9 %), the shoulder (45.5 %) or the waist (45.5 %), the results revealed a preferential DNA release from the top and shoulder of the geminate particle. INTRODUCTIONThe small plant pathogenic geminiviruses are distributed all over the world and have caused severe economic damages in tropical and subtropical countries (Moffat, 1999). African cassava mosaic virus (ACMV) is the most prevalent pathogen of cassava in Africa (Fauquet & Fargette, 1990); it belongs to the genus Begomovirus (Stanley et al., 2005), and is transmitted by the whitefly Bemisia tabaci (Gennadius). Its bipartite genome consists of two circular single-stranded DNA molecules (DNA A and DNA B). The three-dimensional structure of the geminate (twin) ACMV particles has been resolved by cryo-electron microscopy (EM) and image reconstruction (Böttcher et al., 2004). The two incomplete T51 icosahedra of the virion are formed by 110 copies of a single capsid protein (CP) with pentameric capsomere organization. Each half of the geminate particle is built up by 11 pentameric capsomeres, one pentamer missing to complete a T51 icosahedron. The two halves are joined at the place of the missing capsomeres, forming the waist of the particle (see Fig. 7). The two capsomeres at both ends of the particle with strict fivefold symmetry will be called the 'top capsomeres', the adjacent five capsomeres on each side of the virion with local fivefold symmetry will be called the 'shoulder capsomeres' and the five remaining capsomeres at the waist will be called the 'waist capsomeres' (see Fig. 7). The single CP possesses a molecular mass of 30.1 kDa and a calculated pI of 10.0. Each geminate particle encapsidates one circular DNA molecule so that two virions are needed for infection in case of bipartite geminiviruses.Encapsidating the viral genome, the geminivirus CP is important for insect transmission (Briddon et al., 1990; Höfer et al., 1997; Höhnle et al., 2001;Kheyr-Pour et al., 2000; Noris et al., 1998) and transport of the...

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Section: Introductionmentioning

confidence: 99%

Disassembly of African cassava mosaic virus

Kittelmann

Jeske

2008

Journal of General Virology

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“…We do not know whether the proposed size selection capability of NSP is biologically functional until the transport complex has been isolated from infected plants. On the other hand, CP must be able to package viral ssDNA of genomic and subgenomic sizes to form twinned particles or half-size solitary particles (12,56). These ssDNA samples were obviously excluded from the protein binding in the gel mobility shift assay (Fig.…”

Section: Discussionmentioning

confidence: 99%

“…Geminiviral capsids are composed of a single CP, encoded by the gene V1, V2, or AV1 (also known as AR1), depending on the geminivirus (56). The geminivirus genome may be segmented (bipartite) or not (monopartite), and in both cases one DNA molecule occupies the complete twinned particle (3,56).…”

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Interaction of DNA with the Movement Proteins of Geminiviruses Revisited

Hehnle

Wege

Jeske

2004

J Virol

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Geminiviruses manage the transport of their DNA within plants with the help of three proteins, the coat protein (CP), the nuclear shuttle protein (NSP), and the movement protein (MP). The DNA-binding capabilities of CP, NSP, and MP of Abutilon mosaic virus (AbMV; family Geminiviridae; genus Begomovirus) were scrutinized using gel mobility shift assays and electron microscopy. CP and NSP revealed a sequence-independent affinity for both double-stranded and single-stranded DNA, as has been previously reported for other begomoviruses. MP interacted selectively with dimeric supercoiled plasmid DNA in the electrophoretic assay. Further apparent size-and form-selective binding capacities of MP have been previously reported for another geminivirus (Bean dwarf mosaic virus), but in the case of AbMV, they have been identified as the result of electrophoretic interference rather than of complex formation. Without these complications, electron microscopy confirmed the assembly of double-stranded supercoiled DNA with NSP and MP into conspicuous structures and provided the first direct evidence for cooperative interaction of MP, NSP, and DNA. Based on these results and previous ones, a transport model of geminiviruses is discussed in which NSP packages DNA and MP anchors this complex to the protoplasmic leaflets of plasma membranes and microsomes for cell-to-cell movement.

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“…Their DNA is packed into icosahedral twin particles (8,83). Four geminivirus genera have been described, differing in genome organization, host range, and insect vector (67).…”

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Conformation-Selective Methylation of Geminivirus DNA

Paprotka

Deuschle

Metzler

et al. 2011

J Virol

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Geminiviruses with small circular single-stranded DNA genomes replicate in plant cell nuclei by using various double-stranded DNA (dsDNA) intermediates: distinct open circular and covalently closed circular as well as heterogeneous linear DNA. Their DNA may be methylated partially at cytosine residues, as detected previously by bisulfite sequencing and subsequent PCR. In order to determine the methylation patterns of the circular molecules, the DNAs of tomato yellow leaf curl Sardinia virus (TYLCSV) and Abutilon mosaic virus were investigated utilizing bisulfite treatment followed by rolling circle amplification. Shotgun sequencing of the products yielded a randomly distributed 50% rate of C maintenance after the bisulfite reaction for both viruses. However, controls with unmethylated single-stranded bacteriophage DNA resulted in the same level of C maintenance. Only one short DNA stretch within the C2/C3 promoter of TYLCSV showed hyperprotection of C, with the protection rate exceeding the threshold of the mean value plus 1 standard deviation. Similarly, the use of methylation-sensitive restriction enzymes suggested that geminiviruses escape silencing by methylation very efficiently, by either a rolling circle or recombination-dependent replication mode. In contrast, attempts to detect methylated bases positively by using methylcytosine-specific antibodies detected methylated DNA only in heterogeneous linear dsDNA, and methylation-dependent restriction enzymes revealed that the viral heterogeneous linear dsDNA was methylated preferentially.Methylation of DNA is commonly investigated using methylation-sensitive restriction enzymes and bisulfite sequencing, which converts unmethylated cytosines into uracil. The products are usually amplified by PCR and sequenced after bacterial cloning (14, 23). The critical steps in various protocols are the complete conversion of unmethylated cytosines to uracil (26, 78) and the design of appropriate primers for the converted DNA (reviewed in references 58 and 85). Several bioinformatic tools have been developed to analyze the results (9, 46-48, 66, 71), including recent improvements for the analysis of plant DNA cytosine methylation (27,35).Eukaryotes methylate cytosine at C 5 by methyltransferases, which differ between plants, fungi, and mammals (reviewed in reference 25). In mammals, symmetric CpG sites are usually preferred, whereas nearly every cytosine residue in plant DNA can be methylated (reviewed in reference 5). As a result, only 2 to 8% of mammalian DNA is methylated, compared to up to 50% of DNA in higher plants (reviewed in reference 84). The methylation status is highly dynamic. In plants, demethylation is mediated by DNA glycosylases and strand cleavage (84), a mechanism which would inactivate single-stranded DNA (ssDNA). In addition to C-methylation, N 6 -adenine methylation is well known for bacteria but rarely described for plants (19,74).The circular ssDNA-containing geminiviruses (reviewed in reference 37) are important plant pathogens causing severe damag...

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Structure of the Maize Streak Virus Geminate Particle

Cited by 184 publications

References 33 publications

Disassembly of African cassava mosaic virus

Disassembly of African cassava mosaic virus

Interaction of DNA with the Movement Proteins of Geminiviruses Revisited

Conformation-Selective Methylation of Geminivirus DNA

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