Interaction of DNA with the Movement Proteins of Geminiviruses Revisited

Plant viruses move through plasmodesmata (PD) either as nucleoprotein complexes (NPCs) or as tubuleguided encapsidated particles with the help of movement proteins (MPs). To explore how and why MPs specialize in one mechanism or the other, we tested the exchangeability of MPs encoded by DNA and RNA virus genomes by means of an engineered alfalfa mosaic virus (AMV) system. We show that Caulimoviridae (DNA genome virus) MPs are competent for RNA virus particle transport but are unable to mediate NPC movement, and we discuss this restriction in terms of the evolution of DNA virus MPs as a means of mediating DNA viral genome entry into the RNA-trafficking PD pathway.

mentioning

confidence: 99%

Caulimoviridae Tubule-Guided Transport Is Dictated by Movement Protein Properties

Sánchez‐Navarro

Fajardo

Zicca

et al. 2010

“…For bipartite begomoviruses, this process requires two proteins, encoded by the component designated DNA B: the nuclear shuttle protein (NSP) and the cell-to-cell movement protein (MP). These proteins act cooperatively to move the viral DNA from its site of replication in the nucleus to the cytoplasm and into adjacent plant cells (32).The geminivirus MP and NSP recognize DNA in a form-and size-specific manner (12,29). The NSP shuttles newly replicated viral DNA between the nucleus and the cytoplasm (42).…”

mentioning

confidence: 99%

“…The geminivirus MP and NSP recognize DNA in a form-and size-specific manner (12,29). The NSP shuttles newly replicated viral DNA between the nucleus and the cytoplasm (42).…”

mentioning

confidence: 99%

The Nuclear Shuttle Protein ofTomato Leaf Curl New Delhi VirusIs a Pathogenicity Determinant

Hussain

Mansoor

Iram

et al. 2005

Geminiviruses are single-stranded DNA viruses that infect a broad range of dicotyledonous and monocotyledonous plants. Viruses of the family Geminiviridae have been classified into four genera based on host range and genome organization (30). Of these, the whitefly-transmitted geminiviruses (genus Begomovirus) are the largest group, with more than 100 virus species identified so far (8). Geminiviruses replicate in the nuclei of host cells by a rolling-circle replication mechanism (reviewed in reference 11). For the propagation of infection in the host, these viruses encode movement proteins that direct the viral genome to the cortical cytoplasm and across the barrier of the cell wall. For bipartite begomoviruses, this process requires two proteins, encoded by the component designated DNA B: the nuclear shuttle protein (NSP) and the cell-to-cell movement protein (MP). These proteins act cooperatively to move the viral DNA from its site of replication in the nucleus to the cytoplasm and into adjacent plant cells (32).The geminivirus MP and NSP recognize DNA in a form-and size-specific manner (12,29). The NSP shuttles newly replicated viral DNA between the nucleus and the cytoplasm (42). MP traps these NSP-viral DNA complexes in the cytoplasm and redirects them to and across the plant cell wall (24,43). In adjacent cells, the NSP-viral DNA complexes are released, and NSP targets the viral DNA to the nucleus to initiate new rounds of infection. This process of movement is highly regulated. Recently, an acetyltransferase has been isolated from Arabidopsis thaliana that interacts with the NSP encoded by the bipartite begomovirus Cabbage leaf curl virus (22). This protein regulates the nuclear export of the viral DNA and is highly conserved in plants.

“…The 5S rRNA gene was partially sequenced using the primer pair 5Ј-TAAGAAAATCTAGAGTGTAAGGAATGTTGGATGCGAT TATAT-3Ј and 5Ј-TTCATTAATACAAGCTTTACCAAAAAAAAAAATACA ACACGAAA-3Ј, as previously described for the bisulfite-converted top strand (4,24). The bacterial plasmid pBluescript II SK(Ϫ) (Stratagene, Amsterdam, Netherlands), with a size similar to that of geminivirus DNA (2,961 bp), was transreplicated with the help of phage R408 to obtain artificial standard phage progeny lacking methylation as described previously (34). Phage corresponding to 10, 50, 100, or 1,000 ng of ssDNA were mixed with leaf samples from uninfected plants, and DNA extraction was performed as described for virus-infected plant tissue.…”

Section: Microorganisms and Plants Agroinfectious Clones Of Tylcsv (mentioning

confidence: 99%

“…(50) and AbMV (X15983 and X15984) (22) were inoculated into the experimental host Nicotiana benthamiana Domin and grown in a greenhouse with supplementary lighting or in a climate chamber as described previously (81), under containment according to gene technology license S2. The Escherichia coli bacteria and phages used have been described previously (34). In addition, leaves of naturally occurring AbMV-infected ornamental Abutilon plants (80) were used.…”

mentioning

confidence: 99%

Conformation-Selective Methylation of Geminivirus DNA

Paprotka

Deuschle

Metzler

et al. 2011

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...