| dna and rna polymerase activities of nuclei and hypotonic extracts of nuclei isolated from tomato golden mosaic virus infected tobacco leaves. | nuclei and hypotonically leached extracts of nuclei prepared from tomato golden mosaic virus (tgmv)-infected nicotiana benthamiana leaves have been used in in vitro dna and rna polymerisation reactions. the synthesis of virus-specific dna was resistant to aphidicolin, sensitive to n-ethylmaleimide and dideoxy ttp, and stimulated by kc1 and atp. variably virion (+) and complementary (-) strand dna of both the a and b genomic components were synthesised. virus-specific rna was synthesised in react ... | 1985 | 4069999 |
| the nucleotide sequence of maize streak virus dna. | the nucleotide sequence of the dna of maize streak virus (msv) has been determined. the data were accommodated into one dna circle of 2687 nucleotides, in contrast to previously characterised geminiviruses which have been shown to possess two circles of dna. comparison of the nucleotide sequences of the dna of msv with those of cassava latent virus (clv) and tomato golden mosaic virus (tgmv) showed no detectable homology. analysis of open reading frames revealed seven potential coding regions fo ... | 1984 | 6526009 |
| chromosomal location of endogenous geminivirus-related dna sequences in nicotiana tabacum l. | the n. tabacum (tobacco) nuclear genome carries approximately 25 multiple direct repeats of a geminivirus-related dna (grd) sequence that probably arose by illegitimate recombination, following geminivirus infection, during nicotiana evolution. each grd repeat carries sequences similar to the geminiviral al1 gene of the tomato golden mosaic virus (tgmv), encoding a protein required for viral dna replication, plus the cis-essential replication origin. using a cloned 14-kb grd repeat sequence as a ... | 1995 | 7551549 |
| complementation of african cassava mosaic virus ac2 gene function in a mixed bipartite geminivirus infection. | we have previously demonstrated that african cassava mosaic virus (acmv) dnas a and b efficiently complement the systemic spread of tomato golden mosaic virus (tgmv) dna a when co-agroinoculated onto nicotiana benthamiana. here, we show that a mixture of an acmv dna a ac2 mutant and dna b that is normally unable to systemically infect n. benthamiana can do so at low frequency when co-agroinoculated with tgmv dna a. analysis of viral dna showed that the ac2 mutation was retained during infection. ... | 1995 | 7561766 |
| sequence homology among the coat proteins of gemini viruses. | the coat proteins of the gemini viruses - african cassava latent virus, tomato golden mosaic virus and maize streak virus - are shown to have reasonable to good amino acid sequence homology. it is suggested that the maize streak virus genome is ancestral and the bipartite genomes of the other viruses evolved from it. | 1985 | 4026858 |
| potential gene products of bean golden mosaic virus have higher sequence homologies to those of tomato golden mosaic virus than to those of cassava latent virus. | comparison of the nucleotide sequences of the dnas of bean golden mosaic virus (bgmv), tomato golden mosaic virus (tgmv) and cassava latent virus (clv) revealed a fairly close relationship between bgmv dna1, tgmv dna1, and clv dna1 and a comparatively distant relationship between bgmv dna2, tgmv dna2, and clv dna2. the 200-base region common to the two dnas of each virus had little sequence homology, except for a highly conserved 33-36 base sequence potentially capable of forming a stable hairpi ... | 1988 | 3238924 |
| transient expression of heterologous rnas using tomato golden mosaic virus. | the genome of the geminivirus tomato golden mosaic virus (tgmv) consists of two circular dna molecules designated as components a and b. the a component contains the only virally-encoded function required for autonomous replication in infected plant cells. we used agroinoculation of petunia leaf discs with the a component to develop a transient expression system which permits direct examination of viral transcripts by s1 nuclease protection. the ar1 gene, which encodes the tgmv coat protein, was ... | 1988 | 3205715 |
| defective viral dna ameliorates symptoms of geminivirus infection in transgenic plants. | nicotiana benthamiana was transformed with a single copy of a tandem repeat of subgenomic dna b isolated from plants infected with a kenyan isolate of the bipartite geminivirus african cassava mosaic virus. symptoms in transformed plants were less severe than in nontransformed controls when challenged with virus or cloned dna of kenyan or nigerian isolates. symptom amelioration was associated with the mobilization and amplification of the subgenomic dna, producing a comparable reduction in the a ... | 1990 | 2385593 |
| transactivation in a geminivirus: al2 gene product is needed for coat protein expression. | the beta-glucuronidase (gus) reporter gene was used to replace the coat protein gene (open reading frame ar1) of tomato golden mosaic virus (tgmv) and transiently expressed in tobacco protoplasts. while these tgmv/gus genomes gave a high level of gus activity, genomes which also contained a mutation in the al2 open reading frame (tgmv/gus/al2-) did not express gus. gus activity could be restored by cotransfecting protoplasts with the tgmv/gus/al2- genome and a wild-type tgmv genome. thus, the al ... | 1991 | 1984661 |
| functional expression of the leftward open reading frames of the a component of tomato golden mosaic virus in transgenic tobacco plants. | the genome of the geminivirus tomato golden mosaic virus (tgmv) consists of two circular dna molecules designated as components a and b. we have constructed nicotiana benthamiana plants that are transgenic for the three overlapping open reading frames, al1, al2, and al3, from the left side of tgmv a. in the transgenic plants, the al open reading frames are under the control of the cauliflower mosaic virus (camv) 35s promoter. in tgmv infectivity assays, seven of 10 transgenic lines complemented ... | 1989 | 2562559 |
| systemic movement and symptom production following agroinoculation with a single dna of tomato yellow leaf curl geminivirus (thailand). | two different dna species were cloned from purified tomato yellow leaf curl geminivirus particles after annealing a specific primer to virus dna and generating a second strand; both were approximately 2.8 kbp in length. one clone contains sequences which hybridize to the coat protein gene of tomato golden mosaic virus and most likely represents the a dna of tomato yellow leaf curl virus (thailand). the other clone may represent the b dna of this geminivirus. both clones contain short sequences w ... | 1990 | 2219706 |
| infectivity and complete nucleotide sequence of the cloned genomic components of a bipartite squash leaf curl geminivirus with a broad host range phenotype. | through cloning and molecular analysis we have identified two highly homologous bipartite geminiviruses as causing squash leaf curl disease. mechanical and agrobacterium-mediated inoculation of plants with cloned viral dna components identified the two genomic components of sqlcv-e, a squash leaf curl virus with an unexpectedly broad host range for a whitefly-transmitted geminivirus. nucleotide sequence analysis of the genome of this virus showed it to have the same bipartite component organizat ... | 1991 | 1984668 |
| expression of an antisense viral gene in transgenic tobacco confers resistance to the dna virus tomato golden mosaic virus. | transgenic tobacco plants carrying a genetic cassette including an antisense dna sequence of the virally encoded al1 gene of the geminivirus tomato golden mosaic virus (tgmv) were constructed; al1 encodes a protein absolutely required for tgmv dna replication. these genetic cassettes also contained, on the same transcription unit, a gene encoding hygromycin resistance, which allowed selection for concomitant expression of the antisense gene. in transgenic lines, rna transcripts of the predicted ... | 1991 | 1862097 |
| molecular characterization of the al3 protein encoded by a bipartite geminivirus. | the genome of tomato golden mosaic virus (tgmv) is composed of two circular, single-stranded dna molecules that together contain 6 open reading frames (orfs). three of these orfs (designated al1, al2, and al3) overlap and are specified by multiple polycistronic mrnas. no rna specifying the al3 orf alone has been detected, suggesting that the al3 gene product is translated from an internal orf. a recombinant histidine-tagged-al3 fusion protein was purified from escherichia coli and used to raise ... | 1994 | 8030214 |
| synthesis of the tomato golden mosaic virus al1, al2, al3 and al4 proteins in vitro. | transcripts derived from the leftward region of tomato golden mosaic virus dna a were translated in wheat-germ and rabbit reticulocyte lysate systems. the largest protein (m(r) 40k) produced from transcripts encompassing open reading frame (orf) al1 was identified as the al1 protein by immunoprecipitation with al1-specific antibodies. however the main product was a protein of m(r) 10k, that was shown by in vitro mutagenesis to be the product of al4, an orf contained within al1 dna in a different ... | 1994 | 8046385 |
| expression of tgmv antisense rna in transgenic tobacco inhibits replication of bctv but not acmv geminiviruses. | transgenic tobacco plants expressing an antisense rna targeted against tomato golden mosaic virus (tgmv) show reduced/no symptoms and viral dna accumulation upon tgmv infection [5]. the targeted region includes the al1 gene, encoding an essential viral replication protein. this dna sequence is conserved in various other geminiviruses, suggesting they too might show inhibition of replication in these plants. we infected leaf material with african cassava mosaic virus (acmv) and beet curly top vir ... | 1994 | 8111023 |
| dna methylation inhibits propagation of tomato golden mosaic virus dna in transfected protoplasts. | the effects of methylation on plant viral dna replication have been studied in nicotiana tabacum protoplasts transfected with dna of the geminivirus tomato golden mosaic virus (tgmv). the transfected cells were also used to determine whether experimentally introduced methylation patterns are maintained in extrachromosomal viral dna. replacement of cytosine residues with 5-methylcytosine (m5c) reduced the amount of viral dna which accumulated in transfected protoplasts. the reduction was observed ... | 1992 | 1558945 |
| sequence-specific interaction with the viral al1 protein identifies a geminivirus dna replication origin. | the bipartite geminiviruses such as tomato golden mosaic virus (tgmv) and squash leaf curl virus (sqlcv) have two single-stranded circular genomic dnas, the a and b components, thought to be replicated from double-stranded circular dna intermediates. although it has been presumed that the origin sequences for viral replication are located in the highly conserved 200-nucleotide common region (cr) present in both genomic components and that the viral-encoded al1 protein interacts with these sequen ... | 1992 | 1392596 |
| african cassava mosaic virus di dna interferes with the replication of both genomic components. | natural infections of the geminivirus african cassava mosaic virus (acmv) are known to be associated with low levels of defective interfering (di) dnas. recently it has been demonstrated that extrachromosomal copies of the di dna, mobilized and amplified from an integrated di dna dimer, can ameliorate acmv symptoms in transformed nicotiana benthamiana, providing a possible means for the control of cassava mosaic disease. to further understand the molecular basis of the interference phenomenon, w ... | 1991 | 1853559 |
| tomato golden mosaic virus leftward gene expression: autoregulation of geminivirus replication protein. | the genome of the geminivirus tomato golden mosaic virus (tgmv) consists of two dna components, designated dna a and dna b. dna a encodes al1, the only viral protein required for dna replication. al1 protein interacts specifically with sequences in the common region that is conserved between the two genome components, near sequences involved in the transcription of complementary sense genes encoding bl1 protein and the al1 protein itself. in the experiments described here, we replaced the al1 an ... | 1993 | 8317105 |
| interaction between a geminivirus replication protein and origin dna is essential for viral replication. | the geminivirus, tomato golden mosaic virus (tgmv), encodes one protein, al1, that is absolutely required for viral dna replication. al1 interacts with the tgmv dna genome by binding specifically to the viral origin of replication. we have investigated the nature and significance of al1/origin interactions in vitro and in vivo by using competitive dna binding and transient replication assays. competition assays established that a 13-base pair (bp) element (5'-ggtagtaaggtag) containing two 5-bp d ... | 1994 | 8132573 |
| specificity of bipartite geminivirus movement proteins. | pseudorecombinants produced by exchanging genome components (dnas a and b) of the geminiviruses african cassava mosaic virus (acmv) and indian cassava mosaic virus (icmv), acmv, and tomato golden mosaic virus (tgmv), and tgmv and abutilon mosaic virus (abmv) are not infectious in their common host nicotiana benthamiana. in each case, dna a was unable to trans-replicate the heterogenomic dna b component in a n. benthamiana leaf disc assay. the non-viability of the pseudorecombinants has been expl ... | 1993 | 8372440 |
| tomato golden mosaic virus a component dna replicates autonomously in transgenic plants. | phenotypically normal petunia plants carrying chromosomal inserts of either the tomato golden mosaic virus (tgmv) a or the b component dna, as single or tandem inserts, were obtained using an agrobacterium tumefaciens ti plasmid-based transformation system. southern hybridization analysis revealed that the tandem, direct-repeat a plants contained free single and double stranded a component dnas. no free b component dna was detected in plants carrying tandem repeats of the b component. progeny of ... | 1986 | 3708687 |
| characterisation of multimeric dna forms associated with tomato golden mosaic virus infection. | homodimeric and trimeric double-stranded dna forms of both components of the genome of the geminivirus, tomato golden mosaic virus have been isolated from infected nicotiana tabacum plants and characterised. | 1988 | 3291824 |
| size reversion of african cassava mosaic virus coat protein gene deletion mutants during infection of nicotiana benthamiana. | mutants of african cassava mosaic virus containing extensive deletions across the coat protein gene that remove up to one-third of the genomic component have been constructed and shown to be infectious when mechanically inoculated onto nicotiana benthamiana by leaf abrasion. using n. tabacum protoplasts we demonstrate that mutant pclv.cp delta 11, containing a 712 bp deletion, is competent for replication in its deleted form. however, systemic spread of pclv. cp delta 11 and other deletion mutan ... | 1989 | 2732690 |
| tgmv replication protein al1 preferentially binds to single-stranded dna from the common region. | the al1 protein of tomato golden mosaic virus (tgmv) is encoded by the viral dna and has been shown to be essential for viral dna replication. we have over-expressed the al1 open reading frame in e. coli and purified the protein from bacterial extracts to near homogeneity. using various different techniques we have studied the interaction of the al1 protein with dna. the al1 protein is able to bind to dna containing the common region of the viral genome, which can be demonstrated by photochemica ... | 1993 | 8454066 |
| selection for wild type size derivatives of tomato golden mosaic virus during systemic infection. | a chimeric tomato golden mosaic virus (tgmv) a component dna, which results from replacement of the coding region of the viral coat protein gene (cp) with the larger bacterial beta-glucuronidase coding sequence (gus), can replicate in agroinoculated leaf discs but is unstable in systemically infected plants (1). we have made similar replacements of the tgmv cp gene with the gus coding sequence in both the sense and antisense orientations. both derivatives replicated in leaf discs inoculated via ... | 1990 | 2336387 |
| virus and host-specific adaptations in the bl1 and br1 genes of bipartite geminiviruses. | the host range of individual geminiviruses may be quite narrow, and closely related viruses can exhibit distinct host adaptations. two such bipartite geminiviruses are bean golden mosaic virus (gbmv) and tomato golden mosaic virus (tgmv). in both, the bl1 and br1 genes are required for the spread of virus infection in plants. we have investigated the contributions of bl1 and br1 to host-specific phenotypes of bgmv and tgmv by constructing hybrid viruses in which these coding regions were exchang ... | 1995 | 8553533 |
| a dna structure is required for geminivirus replication origin function. | the genome of the geminivirus tomato golden mosaic virus (tgmv) consists of two single-stranded circular dnas, a and b, that replicate through a rolling-circle mechanism in nuclei of infected plant cells. the tgmv origin of replication is located in a conserved 5' intergenic region and includes at least two functional elements: the origin recognition site of the essential viral replication protein, al1, and a sequence motif with the potential to form a hairpin or cruciform structure. to address ... | 1996 | 8523519 |
| in vivo analysis of plant pre-mrna splicing using an autonomously replicating vector. | in this paper, we demonstrate that an autonomously replicating plant expression vector can be used for analysis of pre-mrna splicing determinants in intact dicot cells. this vector system relies on the agrobacterium-mediated transfection of leaf discs with the a component of the geminivirus tomato golden mosaic virus (tgmv). insertion of intron sequences between viral promoter and terminator sequences results in the production of high levels of pre-mrna transcripts that are effectively and accur ... | 1991 | 2057358 |
| host and viral factors determine the dispensability of coat protein for bipartite geminivirus systemic movement. | geminiviruses have unique, twinned icosahedral particles which encapsidate circular single-stranded dna. their genomes are composed of either one or two dna segments. monopartite geminiviruses absolutely require a functional coat protein (cp) for infectivity, whereas bipartite geminivirus cp null mutants can infect plants systemically. however, we show here that a cp mutant of the bipartite tomato golden mosaic virus (tgmv), which can infect nicotiana benthamiana systemically, is confined to the ... | 1996 | 8615033 |
| interactions between geminivirus replication proteins. | geminiviruses are small dna viruses that replicate in the nuclei of infected plant cells. the closely related geminiviruses tomato golden mosaic virus and bean golden mosaic virus each encode a protein, al1, that catalyzes the initiation of rolling-circle replication. both viruses also specify a second replication protein, al3, that greatly enhances the level of viral dna accumulation. using recombinant proteins produced in a baculovirus expression system, we showed that al1 copurifies with a pr ... | 1996 | 8794317 |
| kinetics of tomato golden mosaic virus dna replication and coat protein promoter activity in nicotiana tabacum protoplasts. | we have analyzed the replication kinetics of the dna a and dna b genome components of the geminivirus tomato golden mosaic virus (tgmv) in protoplasts derived from nicotiana tabacum suspension culture. in addition, the kinetics of tgmv coat protein promoter activity, as measured by expression of a beta-glucuronidase (gus) reporter, have been examined. in our protoplast system, double-stranded dna forms of both viral genome components appeared by 18 hr post-transfection, while single-stranded dna ... | 1992 | 1736521 |
| transfection of heteroduplexes containing uracil.guanine or thymine.guanine mispairs into plant cells. | we have compared the fate of u.g mispairs or analogous t.g mispairs in dna heteroduplexes transfected into tobacco protoplasts. the heteroduplex dna consisted of tomato golden mosaic virus dna sequences in the escherichia coli vectors puc118 or puc119. after transfection, the mismatched u residues were lost with an efficiency of greater than 95%, probably as a result of the uracil-dna glycosylase pathway for excision of u residues in any sequence context. in contrast to the preferential removal ... | 1992 | 1515601 |
| inhibition of african cassava mosaic virus systemic infection by a movement protein from the related geminivirus tomato golden mosaic virus. | plant viruses encode proteins that mediate their movement through the host plant leading to the establishment of a systemic infection. we have analyzed the effect of tomato golden mosaic virus (tgmv) genes bl1 and br1, which are thought to be involved in the process of virus movement, on the infectivity of african cassava mosaic virus (acmv) in nicotiana benthamiana. recombinant genomes were constructed by replacing the acmv coat protein coding sequence with those of either bl1 or br1. replicati ... | 1992 | 1546454 |
| conserved sequence and structural motifs contribute to the dna binding and cleavage activities of a geminivirus replication protein. | tomato golden mosaic virus (tgmv), a member of the geminivirus family, has a single-stranded dna genome that replicates through a rolling circle mechanism in nuclei of infected plant cells. tgmv encodes one essential replication protein, al1, and recruits the rest of the dna replication apparatus from its host. al1 is a multifunctional protein that binds double-stranded dna, catalyzes cleavage and ligation of single-stranded dna, and forms oligomers. earlier experiments showed that the region of ... | 1998 | 9733736 |
| a geminivirus replication protein is a sequence-specific dna binding protein. | the genome of the geminivirus tomato golden mosaic virus (tgmv) consists of two circular dna molecules designated as components a and b. the a component encodes the only viral protein, al1, that is required for viral replication. we showed that al1 interacts specifically with tgmv a and b dna by using an immunoprecipitation assay for al1:dna complex formation. in this assay, a monoclonal antibody against al1 precipitated al1:tgmv dna complexes, whereas an unrelated antibody failed to precipitate ... | 1992 | 1498611 |
| geminivirus replication origins have a modular organization. | tomato golden mosaic virus (tgmv) and bean golden mosaic virus (bgmv) are closely related geminiviruses with bipartite genomes. the a and b dna components of each virus have cis-acting sequences necessary for replication, and their a components encode trans-acting factors are required for this process. we showed that virus-specific interactions between the cis- and trans-acting functions are required for tgmv and bgmv replication in tobacco protoplasts. we also demonstrated that, similar to the ... | 1994 | 8180499 |
| multiple cis elements contribute to geminivirus origin function. | the genome of the geminivirus tomato golden mosaic virus (tgmv) consists of two circular dna molecules which are dissimilar in sequence except for a highly conserved 200-bp common region that includes the origin for rolling circle replication. to better characterize the plus-strand origin, we analyzed the capacities of various tgmv common region sequences to support episomal replication in tobacco protoplasts when the viral replication proteins al1 and al3 were supplied in trans. these experimen ... | 1998 | 9514968 |
| bipartite geminivirus host adaptation determined cooperatively by coding and noncoding sequences of the genome. | bipartite geminiviruses are small, plant-infecting viruses with genomes composed of circular, single-stranded dna molecules, designated a and b. although they are closely related genetically, individual bipartite geminiviruses frequently exhibit host-specific adaptation. two such viruses are bean golden mosaic virus (bgmv) and tomato golden mosaic virus (tgmv), which are well adapted to common bean (phaseolus vulgaris) and nicotiana benthamiana, respectively. in previous studies, partial host ad ... | 2000 | 11080490 |
| two domains of the al1 protein mediate geminivirus origin recognition. | the geminiviruses tomato golden mosaic virus (tgmv) and bean golden mosaic virus (bgmv) have bipartite genomes. their a and b dna components contain cis-acting sequences that function as origins of replication, while their a components encode the trans-acting replication proteins--al1 and al3. earlier experiments demonstrated that virus-specific interactions between the cis- and trans-acting functions are required for tgmv and bgmv replication and that the al1 proteins of the two viruses specifi ... | 1997 | 9426458 |
| the tomato golden mosaic virus transactivator (trap) is a single-stranded dna and zinc-binding phosphoprotein with an acidic activation domain. | the al2 gene found in members of the genus begomovirus of the geminiviridae encodes a transcriptional activator protein (trap; also known as al2, ac2, or c2 protein). trap activates expression from the viral coat protein (cp) and br1 movement gene promoters in mesophyll cells and protoplasts and acts to derepress the cp promoter in vascular tissue. the experiments presented here were designed to elucidate some of the biochemical properties of this multifunctional regulatory protein and to define ... | 1999 | 10544077 |
| plants expressing tomato golden mosaic virus al2 or beet curly top virus l2 transgenes show enhanced susceptibility to infection by dna and rna viruses. | the al2 gene of the geminivirus tomato golden mosaic virus (tgmv) encodes a transcriptional activator protein (trap) that is required for efficient expression of the viral coat protein (cp) and br1 gene promoters. in contrast, l2, the positional homolog of al2 in the related beet curly top virus (bctv), is not required for cp expression, raising questions about the functional relationship between the al2 and l2 gene products. in this study, transgenic nicotiana benthamiana and n. tabacum var. sa ... | 2001 | 11414806 |
| genetic determinants of host-specificity in bipartite geminivirus dna a components. | geminiviruses are small, ssdna-containing plant viruses. bean golden mosaic virus (bgmv) and tomato golden mosaic virus (tgmv) have bipartite genomes, the components of which are designated a and b. although they are closely related, bgmv and tgmv nevertheless exhibit distinct host-specific phenotypes, with bgmv being well adapted to beans and tgmv being well adapted to nicotiana benthamiana. a previous study showed that the two open reading frames (orfs) of dna b only partially determine the ho ... | 1998 | 9837800 |
| genetic analysis of bipartite geminivirus tissue tropism. | the bipartite geminiviruses bean golden mosaic virus (bgmv), cabbage leaf curl virus (cablcv), and tomato golden mosaic virus (tgmv) exhibit differential tissue tropism in nicotiana benthamiana. in systemically infected leaves, bgmv remains largely confined to vascular-associated cells (phloem-limited), whereas cablcv and tgmv can escape into the surrounding mesophyll. previous work established that tgmv bri, the noncoding region upstream from the br1 open reading frame (orf), is required for me ... | 2001 | 11878900 |
| the nucleotide sequence and genome structure of mung bean yellow mosaic geminivirus. | complete nucleotide sequences of the infectious cloned dna components (dna 1 and dna 2) of mung bean yellow mosaic virus (mymv) were determined. mymv dna 1 and dna 2 consists of 2,723 and 2,675 nucleotides respectively. dna 1 and dna 2 have little sequence similarity except for a region of approximately 200 bases which is almost identical in the two molecules. analysis of open reading frames revealed nine potential coding regions for proteins of mol. wt. > 10,000, six in dna 1 and three in dna 2 ... | 1993 | 8231962 |
| tissue specificity of geminivirus infection is genetically determined. | the types of cells and tissues infected by a virus define its tissue tropism. determinants of tissue tropism in animal-infecting viruses have been extensively investigated, but little is known about plant viruses in this regard. some geminiviruses in the genus begomovirus exhibit phloem limitation and are restricted to cells of the vascular system, whereas others can invade mesophyll tissue. to identify viral genetic determinants of tissue tropism, we established a model system using two begomov ... | 2000 | 11090223 |
| adaptation from whitefly to leafhopper transmission of an autonomously replicating nanovirus-like dna component associated with ageratum yellow vein disease. | ageratum yellow vein disease is caused by the whitefly-transmitted monopartite begomovirus ageratum yellow vein virus and a dna beta satellite component. naturally occurring symptomatic plants also contain an autonomously replicating nanovirus-like dna 1 component that relies on the begomovirus and dna beta for systemic spread and whitefly transmission but is not required for maintenance of the disease. here, we show that systemic movement of dna 1 occurs in nicotiana benthamiana when co-inocula ... | 2002 | 11907341 |
| identification of a novel receptor-like protein kinase that interacts with a geminivirus nuclear shuttle protein. | despite extensive studies in plant virus-host interactions, the molecular mechanisms of geminivirus movement and interactions with host components remain largely unknown. a tomato kinase protein and its soybean homolog were found to interact specifically with the nuclear shuttle protein (nsp) of tomato golden mosaic virus (tgmv) and tomato crinkle leaf yellows virus (tcrlyv) through yeast two-hybrid screening and in vitro protein binding assays. these proteins, designated lenik (lycopersicon esc ... | 2004 | 14972531 |
| interaction between a geminivirus replication protein and the plant sumoylation system. | geminiviruses are small dna viruses that replicate in nuclei of infected plant cells after accumulation of host replication machinery. tomato golden mosaic virus (tgmv) and tomato yellow leaf curl sardinia virus (tylcsv) encode a protein, repac1 (or rep), that is essential for viral replication. rep/repac1 is an oligomeric protein that binds to double-stranded dna, catalyzes cleavage and ligation of single-stranded dna, and is sufficient for host induction. it also interacts with several host pr ... | 2004 | 14990696 |
| a novel motif in geminivirus replication proteins interacts with the plant retinoblastoma-related protein. | the geminivirus replication factor al1 interacts with the plant retinoblastoma-related protein (prbr) to modulate host gene expression. the al1 protein of tomato golden mosaic virus (tgmv) binds to prbr through an 80-amino-acid region that contains two highly predicted alpha-helices designated 3 and 4. earlier studies suggested that the helix 4 motif, whose amino acid sequence is strongly conserved across geminivirus replication proteins, plays a role in prbr binding. we generated a series of al ... | 2004 | 15078963 |
| regulation of a geminivirus coat protein promoter by al2 protein (trap): evidence for activation and derepression mechanisms. | tomato golden mosaic virus (tgmv) is a bipartite member of the subgroup iii geminiviridae. like all geminiviruses, tgmv replicates in the nucleus of susceptible cells by rolling circle replication (rcr). double-stranded replicative form dna generated during rcr serves as template for the transcription of viral genes by rna polymerase ii and the associated cellular transcription machinery. previous studies in tobacco protoplasts and nicotiana benthamiana leaf discs have shown that the viral al2 g ... | 1997 | 9191840 |
| computer analysis identifies sequence homologies between potential gene products of maize streak virus and those of cassava latent virus and tomato golden mosaic virus. | the amino acid sequences of the putative polypeptides of maize streak virus (msv) have been systematically compared with those of cassava latent virus (clv) and tomato golden mosaic virus (tgmv) using the programme diagon (8).conserved sequences have been detected between peptides encoded by the complementary (-) sense of msv and those of clv and tgmv, viz; the 40 200 mr polypeptide of clv-1 (3) and the 40 285 mr polypeptide of tgmv-a (4) show extensive homologies with the 17 768 mr and 31 388 m ... | 1985 | 24306572 |
| efficient whitefly transmission of african cassava mosaic geminivirus requires sequences from both genomic components. | clones of two subgroup iii geminiviruses, the common strain of tomato golden mosaic virus (cstgmv) and african cassava mosaic virus originating from kenya (acmv-k), were shown to be non-transmissible by whitefiles. lack of transmissibility of cloned acmv-k was investigated by exchanging genomic components with a whitefly-transmissible acmv isolate from nigeria (acmv-nog). neither pseudorecombinant was transmissible, indicating that defects in both genomic components contributed to the lack of tr ... | 1997 | 9225057 |
| adenosine kinase inhibition and suppression of rna silencing by geminivirus al2 and l2 proteins. | most plant viruses are initiators and targets of rna silencing and encode proteins that suppress this adaptive host defense. the dna-containing geminiviruses are no exception, and the al2 protein (also known as ac2, c2, and transcriptional activator protein) encoded by members of the genus begomovirus has been shown to act as a silencing suppressor. here, a three-component, agrobacterium-mediated transient assay is used to further examine the silencing suppression activity of al2 from tomato gol ... | 2005 | 15919897 |
| single-stranded dna of tomato leaf curl virus accumulates in the cytoplasm of phloem cells. | geminiviruses have been reported to replicate in, and localize to, the nuclei of host plant cells. we have investigated the tissue and intracellular distribution of the monopartite tomato leaf curl virus (tlcv) by in situ hybridization. contrary to the current understanding of geminiviral localization, single-stranded (ss) dna of tlcv accumulated in the cytoplasm. tlcv ssdna was also found in the nucleus, as was lower levels of replicative form double-stranded (ds) dna. under the same conditions ... | 2006 | 16457866 |
| distinct viral sequence elements are necessary for expression of tomato golden mosaic virus complementary sense transcripts that direct al2 and al3 gene expression. | transient expression studies using nicotiana benthamiana protoplasts and plants have identified sequences important for transcription of complementary sense rnas derived from tomato golden mosaic virus (tgmv) dna component a that direct expression of al2 and al3. transcription of two complementary sense rnas, initiating at nucleotides 1,935 (al1935) and 1,629 (al1629), is directed by unique sequences located upstream of each transcription initiation site. one element is located between 28 and 12 ... | 2006 | 17153924 |
| rrb1 and rrb2 encode maize retinoblastoma-related proteins that interact with a plant d-type cyclin and geminivirus replication protein. | unlike mammalian and yeast cells, little is known about how plants regulate g1 progression and entry into the s phase of the cell cycle. in mammalian cells, a key regulator of this process is the retinoblastoma tumor suppressor protein (rb). in contrast, g1 control in saccharomyces cerevisiae does not utilize an rb-like protein. we report here the cloning of cdnas from two zea mays genes, rrb1 and rrb2, that encode rb-related proteins. further, rrb2 transcripts are alternatively spliced to yield ... | 1997 | 9271385 |
| peptide aptamers that bind to a geminivirus replication protein interfere with viral replication in plant cells. | the al1 protein of tomato golden mosaic virus (tgmv), a member of the geminivirus family, is essential for viral replication in plants. its n terminus contains three conserved motifs that mediate origin recognition and dna cleavage during the initiation of rolling-circle replication. we used the n-terminal domain of tgmv al1 as bait in a yeast two-hybrid screen of a random peptide aptamer library constrained in the active site of the thioredoxin a (trxa) gene. the screen selected 88 trxa peptide ... | 2006 | 16731923 |
| tomato yellow spot virus, a tomato-infecting begomovirus from brazil with a closer relationship to viruses from sida sp., forms pseudorecombinants with begomoviruses from tomato but not from sida. | geminiviruses are characterized by a circular, single-stranded dna genome and twinned icosahedral particles. begomoviruses (whitefly-transmitted geminiviruses) are a major constraint to crop production worldwide. in brazil, tomato-infecting begomoviruses emerged as serious pathogens over the last 10 years, due to the introduction of a new biotype of the insect vector. tomato yellow spot virus (toysv) is a newly described begomovirus originally isolated from tomato, but phylogenetically closer to ... | 2006 | 17098986 |
| dna abrasion onto plants is an effective method for geminivirus infection and virus-induced gene silencing. | geminiviruses belong to a rapidly growing group of plant pathogens that contribute to crop losses in tropical and subtropical areas of the world. geminivirus infection is a model for plant dna replication and virus/host interactions. geminiviruses are also used as vectors to induce silencing of endogenous genes in several plant species. a method was analyzed for inoculating geminiviruses using plasmid dna rubbed onto leaves in the presence of an abrasive (dna abrasion). although the use of dna a ... | 2007 | 17337069 |
| al1-dependent repression of transcription enhances expression of tomato golden mosaic virus al2 and al3. | studies using nicotiana benthamiana protoplasts have determined that repression of upstream transcription by al1 protein enhances al2 and al3 expression in tomato golden mosaic virus (tgmv). mutations resulting in the inability of tgmv al1 protein to associate with its cognate binding site, result in a decrease in both al2 and al3 expression. reduced expression correlates with an increase in transcription from the al62 start site, and decreased transcription from downstream initiation sites (al1 ... | 2007 | 17407785 |
| a conserved binding site within the tomato golden mosaic virus al-1629 promoter is necessary for expression of viral genes important for pathogenesis. | we have identified a nine base pair sequence in tomato golden mosaic virus that is required for binding of nuclear proteins from tobacco and arabidopsis to viral dna. the sequence is located within the promoter for a 0.7 kb complementary sense mrna (al-1629). mutation of the binding site results in a two- to six-fold reduction in the accumulation of al-1629 mrna, leading to reduced al2 and al3 gene expression. viral sequences located immediately adjacent to the core binding site appear to influe ... | 2007 | 17532021 |
| geminivirus-induced gene silencing of the tobacco retinoblastoma-related gene results in cell death and altered development. | the retinoblastoma-related protein (rbr) is required for cell cycle control and differentiation and is expressed throughout the life of plants and animals. in this study, the tomato golden mosaic virus (tgmv) geminivirus vector was used to silence nbrbr1 in nicotiana benthamiana by microprojectile bombardment into fully developed leaves. similar to previous results using agroinoculation of a tobacco rattle virus silencing vector [park et al. (plant j 42:153, 2005)], developmental defects caused ... | 2007 | 17634748 |
| quantitative evaluation of six different viral suppressors of silencing using image analysis of transient gfp expression. | the effects of six different plant viral suppressors of gene silencing were compared using an automated image collection and analysis system developed for continual monitoring of gfp expression. suppressors were introduced into lima bean cotyledonary tissues either as 3'-gfp translational fusions or as co-introductions with the gfp gene on a separate plasmid. the resultant transient expression profiles for each suppressor depended on whether the suppressor was introduced as a fusion or co-introd ... | 2009 | 19198843 |
| functional equivalence of late gene promoters in bean golden mosaic virus with those in tomato golden mosaic virus. | in the bipartite geminivirus tomato golden mosaic virus (tgmv), the activity of late gene promoters is up-regulated by the multifunctional viral protein al2. cis-acting sequences required for al2-mediated promoter responses have not been well characterized. however, nucleotide sequence analysis has implicated a motif termed the conserved late element (cle). the cle is present in tgmv and many other begomoviruses, although it is not ubiquitous. here we analysed the regulation of late gene express ... | 2001 | 11172109 |
| expression of functional replication protein from tomato golden mosaic virus in transgenic tobacco plants. | the a component of the bipartite genome of the geminivirus tomato golden mosaic virus (tgmv) encodes the viral protein (al1) that is required for viral dna replication. we have constructed transgenic nicotiana benthamiana plants in which the al1 open reading frame is transcribed under the control of the cauliflower mosaic virus 35s promoter. the transgenic plants, which were phenotypically normal, produced a single transcript from the 35s-al1 construct and a 40-kda protein that cross-reacted wit ... | 1990 | 11607065 |
| high-frequency reversion of geminivirus replication protein mutants during infection. | the geminivirus replication protein al1 interacts with retinoblastoma-related protein (rbr), a key regulator of the plant division cell cycle, to induce conditions permissive for viral dna replication. previous studies of tomato golden mosaic virus (tgmv) al1 showed that amino acid l148 in the conserved helix 4 motif is critical for rbr binding. in this work, we examined the effect of an l148v mutation on tgmv replication in tobacco cells and during infection of nicotiana benthamiana plants. the ... | 2007 | 17670823 |
| functional analysis of a novel motif conserved across geminivirus rep proteins. | members of the geminiviridae have single-stranded dna genomes that replicate in nuclei of infected plant cells. all geminiviruses encode a conserved protein (rep) that catalyzes initiation of rolling-circle replication. earlier studies showed that three conserved motifs-motifs i, ii, and iii-in the n termini of geminivirus rep proteins are essential for function. in this study, we identified a fourth sequence, designated grs (geminivirus rep sequence), in the rep n terminus that displays high am ... | 2010 | 21084480 |
| dual interaction of plant pcna with geminivirus replication accessory protein (ren) and viral replication protein (rep). | geminiviruses replicate their small, single-stranded dna genomes in plant nuclei using host replication machinery. similar to most dicotyledonous plant-infecting geminiviruses, tomato yellow leaf curl sardinia virus (tylcsv) encodes a protein, ren, that enhances viral dna accumulation through an unknown mechanism. earlier studies showed that ren protein from another geminivirus, tomato golden mosaic virus (tgmv), forms oligomers and interacts with rep protein, the only viral protein essential fo ... | 2003 | 12919743 |
| expression of recombinant endostatin in agrobacterium-inoculated leaf disks of nicotiana tabacum var. xanthi. | recombinant endostatin was transiently expressed in agrobacterium-inoculated leaf disks of nicotiana tabacum var. xanthi with a molecular size of 23 kda. expression of endostatin from a replicating vector based on tomato golden mosaic virus (tgmv) was 170% higher at the transcript level and double higher at the protein level than from a control vector of a non-replicating construct. purified recombinant endostatin from tobacco leaf-disks has an anti-proliferative effect on bovine endothelial cel ... | 2004 | 15604777 |
| functional modulation of the geminivirus al2 transcription factor and silencing suppressor by self-interaction. | the dna genomes of geminiviruses have a limited coding capacity that is compensated for by the production of small multifunctional proteins. the al2 protein encoded by members of the genus begomovirus (e.g., tomato golden mosaic virus) is a transcriptional activator, a silencing suppressor, and a suppressor of a basal defense. the related l2 protein of beet curly top virus (genus curtovirus) shares the pathogenicity functions of al2 but lacks transcriptional activation activity. it is known that ... | 2007 | 17715241 |
| coilin, the signature protein of cajal bodies, differentially modulates the interactions of plants with viruses in widely different taxa. | cajal bodies (cbs) are distinct nuclear bodies physically and functionally associated with the nucleolus. in addition to their traditional function in coordinating maturation of certain nuclear rnas, cbs participate in cell cycle regulation, development, and regulation of stress responses. a key "signature" component of cbs is coilin, the scaffolding protein essential for cb formation and function. using an rna silencing (loss-of-function) approach, we describe here new phenomena whereby coilin ... | 2017 | 24637832 |
| interaction between the transcription factor attify4b and begomovirus al2 protein impacts pathogenicity. | the begomovirus al2 protein is a transcriptional activator, a silencing suppressor, and inhibitor of basal defense. al2 forms a complex at the cp promoter, through interaction with a plant-specific dna-binding protein, arabidopsis peapod2 (also known as tify4b). attify4b has three domains (ppd, tify and cct_2) conserved between homologs from different plant species. we confirmed that the al2 protein from tomato golden mosaic virus and cabbage leaf curl virus interacts with tify4b from arabidopsi ... | 2014 | 25011501 |
| identification of sequences required for al2-mediated activation of the tomato golden mosaic virus-yellow vein br1 promoter. | a 108 bp sequence has been identified in the tomato golden mosaic virus-yellow vein (yvtgmv) b component that is necessary and sufficient for al2-mediated activation of the br1 promoter. the sequence appears to have a bipartite arrangement, with elements located between -144 to -77 and -59 to -36 from the transcription start site, with both being required for activation by al2. these sequences are located upstream of a tata box and bind nuclear proteins from spinach, tomato and arabidopsis. thes ... | 2013 | 23486662 |
| the arabidopsis peapod2 transcription factor interacts with geminivirus al2 protein and the coat protein promoter. | the trap protein of bipartite begomoviruses activates the coat protein (cp) promoter in mesophyll and derepresses the promoter in vascular tissue through two sequences, located 60-125 bp and 1.2-1.5 kbp respectively, upstream of the cp gene. trap does not, however, exhibit specific binding to either sequence directly. we have identified a plant-specific dna-binding protein, arabidopsis peapod2 (ppd2), that specifically binds sequences mediating activation of the cp promoter of tomato golden mosa ... | 2009 | 19647846 |
| method: low-cost delivery of the cotton leaf crumple virus-induced gene silencing system. | we previously developed a virus-induced gene silencing (vigs) vector for cotton from the bipartite geminiviruscotton leaf crumple virus (clcrv). the original clcrv vigs vector was designed for biolistic delivery by a gene gun. this prerequisite limited the use of the system to labs with access to biolistic equipment. here we describe the adaptation of this system for delivery by agrobacterium (agrobacterium tumefaciens). we also describe the construction of two low-cost particle inflow guns. | 2012 | 22853641 |
| geminivirus al2 protein induces expression of, and interacts with, a calmodulin-like gene, an endogenous regulator of gene silencing. | rna silencing is an innate cellular response involved in antiviral defense. arabidopsis calmodulin-like protein 39 (at-rgscam) is related to known regulators of rna silencing in tomato and nicotiana tabacum. geminivirus al2 protein functions to suppress post-transcriptional and transcriptional gene silencing, possibly through induction of an endogenous regulator. in support of this, the at-rgscam promoter responds to tomato golden mosaic virus (tgmv) al2 in protoplasts and geminivirus infection ... | 2014 | 25010276 |
| cloned tomato golden mosaic virus back in tomatoes. | clones of tomato golden mosaic virus (tgmv), a key model for geminivirus research, have been transmitted back to their original host tomato for the first time. in contrast to the high pathogenicity in other solanaceous species, tgmv induced only very mild symptoms: a few chlorotic spots on the leaf lamina for the common variant (formerly strain cs), and limited vein yellowing for the yellow vein variant (yv). symptoms disappeared over time, though viral dna remained detectable in newly developed ... | 2012 | 22677771 |
| regulation of tomato golden mosaic virus al2 and al3 gene expression by a conserved upstream open reading frame. | a translational regulatory mechanism for tomato golden mosaic virus (tgmv) complementary-sense gene expression has been characterized. tgmv transcribes two mrnas, al-1935 and al-1629 transcripts, both of which contain the al2 and al3 open reading frames. however, al2 is only expressed from al-1629 whereas al3 is expressed from both. three aug translation initiation codons are located upstream of both the al2 and al3 coding regions, within the 5'-untranslated region (utr) of the al-1935 transcrip ... | 2009 | 19012941 |
| gene silencing from plant dna carried by a geminivirus. | the geminivirus tomato golden mosaic virus (tgmv) replicates in nuclei and expresses genes from high copy number dna episomes. the authors used tgmv as a vector to determine whether episomal dna can cause silencing of homologous, chromosomal genes. two markers were used to asses silencing: (1) the sulfur allele (su) of magnesium chelatase, an enzyme required for chlorophyll formation; and (2) the firefly luciferase gene (luc). various portions of both marker genes were inserted into tgmv in plac ... | 1998 | 15494056 |
| the nucleotide sequence of cloned wheat dwarf virus dna. | restriction analysis and cloning of virus-specific double-stranded dna isolated from plants infected with wheat dwarf virus (wdv) indicated that the virus genome, like that of maize streak virus (msv), consists of a single dna circle. the complete nucleotide sequence of cloned wdv dna (2749 nucleotides) has been determined. comparison of the potential coding regions in wdv dna with those in the dna of two strains of msv suggests that these viruses encode at least two functional proteins, the coa ... | 1985 | 15938050 |
| identification of a minimal sequence required for activation of the tomato golden mosaic virus coat protein promoter in protoplasts. | transient expression studies using a nicotiana benthamiana suspension cell-derived protoplast system have identified a minimal sequence that is necessary and sufficient for activation of the tomato golden mosaic virus coat protein (cp) promoter by the viral trap protein (also called al2). the sequence has a bipartite arrangement in which elements located between -125 to -107 and -96 to -60 from the transcription start site are both required for trap-mediated activation. one of the sequences (-96 ... | 2003 | 12573590 |
| host dna replication is induced by geminivirus infection of differentiated plant cells. | the geminivirus tomato golden mosaic virus (tgmv) replicates in differentiated plant cells using host dna synthesis machinery. we used 5-bromo-2-deoxyuridine (brdu) incorporation to examine dna synthesis directly in infected nicotiana benthamiana plants to determine if viral reprogramming of host replication controls had an impact on host dna replication. immunoblot analysis revealed that up to 17-fold more brdu was incorporated into chromosomal dna of tgmv-infected versus mock-infected, similar ... | 2002 | 12468723 |
| dual interaction of a geminivirus replication accessory factor with a viral replication protein and a plant cell cycle regulator. | geminiviruses replicate their small, single-stranded dna genomes through double-stranded dna intermediates in plant nuclei using host replication machinery. like most dicot-infecting geminiviruses, tomato golden mosaic virus encodes a protein, al3 or c3, that greatly enhances viral dna accumulation through an unknown mechanism. earlier studies showed that al3 forms oligomers and interacts with the viral replication initiator al1. experiments reported here established that al3 also interacts with ... | 2001 | 11162812 |
| complete nucleotide sequence of the infectious cloned dna components of tomato golden mosaic virus: potential coding regions and regulatory sequences. | the nucleotide sequences of the infectious cloned dna components of tomato golden mosaic virus (tgmv) have been determined. dna a (2588 nucleotides) and dna b (2508 nucleotides) have little sequence homology except for a region of 200 bases which is almost identical in the two molecules. analysis of open reading frames revealed six potential coding regions for proteins of mol. wt. >10 000, four in dna a and two in dna b. possible regulatory signals are identified and a model for bidirectional tr ... | 1984 | 16453557 |
| genetic analysis of the tomato golden mosaic virus. ii. the product of the al1 coding sequence is required for replication. | tomato golden mosaic virus (tgmv) belongs to the geminivirus subgroup that is characterized by a split genome consisting of two single-stranded circular dnas. the tgmv a genome component encodes the virus coat protein as well as all of the functions necessary for viral dna replication. analysis of the nucleotide sequence indicates that the tgmv a component has, in addition to the coat protein encoding orf, four overlapping open reading frames (orfs) with the potential to encode proteins of great ... | 1988 | 3405758 |
| the distinct disease phenotypes of the common and yellow vein strains of tomato golden mosaic virus are determined by nucleotide differences in the 3'-terminal region of the gene encoding the movement protein. | in nicotiana benthamiana, the common strain of the bipartite geminivirus tomato golden mosaic virus (cstgmv) induces extensive chlorosis whereas the yellow vein strain (yvtgmv) produces veinal chlorosis on systemically infected leaves. in datura stramonium, cstgmv produces leaf distortion and a severe chlorotic mosaic whereas yvtgmv produces only small chlorotic lesions on systemically infected leaves. genetic recombination and site-directed mutagenesis studies using infectious clones of cstgmv ... | 2001 | 11125157 |
| chromosome condensation induced by geminivirus infection of mature plant cells. | tomato golden mosaic virus (tgmv) is a geminivirus that replicates its single-stranded dna genome through double-stranded dna intermediates in nuclei of differentiated plant cells using host replication machinery. we analyzed the distribution of viral and plant dna in nuclei of infected leaves using fluorescence in situ hybridization (fish). tgmv-infected nuclei showed up to a sixfold increase in total volume and displayed a variety of viral dna accumulation patterns. the most striking viral dna ... | 2000 | 10704366 |
| the multifunctional character of a geminivirus replication protein is reflected by its complex oligomerization properties. | tomato golden mosaic virus (tgmv), a member of the geminivirus family, encodes one essential replication protein, al1, and recruits the rest of the dna replication apparatus from its plant host. tgmv al1 is an oligomeric protein that binds double-stranded dna and catalyzes cleavage and ligation of single-stranded dna. the oligomerization domain, which is required for dna binding, maps to a region that displays strong sequence and structural homology to other geminivirus rep proteins. to assess t ... | 2000 | 10692401 |
| cis elements that contribute to geminivirus transcriptional regulation and the efficiency of dna replication. | the a genomic component of the geminivirus tomato golden mosaic virus (tgmv) contains a 5' intergenic sequence that includes the overlapping al61 promoter and positive-strand origin of dna replication. the tgmv al1 protein negatively regulates its own transcription and mediates origin recognition by binding to a repeated motif shared by the al61 promoter and the viral origin. we examined a series of truncated or mutated 5' intergenic regions in transient expression and replication assay to ident ... | 1997 | 9261423 |
| genetic analysis of beet curly top virus: examination of the roles of l2 and l3 genes in viral pathogenesis. | the monopartite dna genome of beet curly top geminivirus (bctv, strain logan) contains four leftward (complementary sense) open reading frames (orfs) designated l1, l2, l3, and l4. we investigated the functions of the l2 and l3 orfs by mutational analysis. we found that in nicotiana benthamiana and sugarbeet plants, neither a functional l2 nor a functional l3 gene is required for infectivity. double mutants were also infectious, and no evidence for a synergistic effect of these genes was evident ... | 1995 | 7856079 |
| functional domains of a geminivirus replication protein. | tomato golden mosaic virus, a member of the geminivirus family, has a single-stranded dna genome that is replicated and transcribed in infected plant cells through the concerted action of viral and host factors. one viral protein, al1, contributes to both processes by binding to a directly repeated, double-stranded dna sequence located in the overlapping (+) strand origin of replication and al1 promoter. the al1 protein, which occurs as a multimeric complex in solution, also catalyzes dna cleava ... | 1997 | 9092519 |
| altered expression of arabidopsis genes in response to a multifunctional geminivirus pathogenicity protein. | geminivirus ac2 is a multifunctional protein that acts as a pathogenicity factor. transcriptional regulation by ac2 appears to be mediated through interaction with a plant specific dna binding protein, peapod2 (ppd2), that specifically binds to sequences known to mediate activation of the cp promoter of cabbage leaf curl virus (calcuv) and tomato golden mosaic virus (tgmv). suppression of both basal and innate immune responses by ac2 in plants is mediated through inactivation of snrk1.2, an arab ... | 2014 | 25403083 |
| tomato golden mosaic virus open reading frame al4 is genetically distinct from its c4 analogue in monopartite geminiviruses. | tomato golden mosaic virus (tgmv) is a bipartite geminivirus with six well-characterized genes. an additional open reading frame (orf), al4, lies within the essential al1 gene. recent studies of monopartite, dicot-infecting geminiviruses have revealed that mutations in their analogous c4 orfs have host-specific effects on infectivity, symptomatology, virus movement and/or viral dna accumulation. we have investigated whether tgmv has a similar host-specific requirement for al4. the phenotypes of ... | 1996 | 8760447 |
| complementable and noncomplementable host adaptation defects in bipartite geminiviruses. | members of the geminvirus group of plant viruses collectively infect a broad spectrum of species. individual viruses which are genetically very similar may nevertheless have distinct host ranges. two such geminiviruses are tomato golden mosaic virus (tgmv) and been golden mosaic virus (bgmv), for which common hosts have not previously been reported. each virus has two genome components, designated a and b. the a component is capable of autonomous replication and encapsidation, whereas the b comp ... | 1995 | 7676643 |
| a geminivirus induces expression of a host dna synthesis protein in terminally differentiated plant cells. | geminiviruses are plant dna viruses that replicate through dna intermediates in plant nuclei. the viral components required for replication are known, but no host factors have yet been identified. we used immunolocalization to show that the replication proteins of the geminivirus tomato golden mosaic virus (tgmv) are located in nuclei of terminally differentiated cells that have left the cell cycle. in addition, tgmv infection resulted in a significant accumulation of the host dna synthesis prot ... | 1995 | 7647562 |
| geminivirus pathogenicity protein c4 interacts with arabidopsis thaliana shaggy-related protein kinase atsketa, a component of the brassinosteroid signalling pathway. | beet curly top virus (bctv) c4 interacted with two members of the shaggy-related protein kinase family (atsketa and atskzeta) and a putative leucine-rich repeat receptor-like kinase (lrr-rlk) in a yeast two-hybrid assay. tomato golden mosaic virus (tgmv) ac4 also bound with similar efficiency to atsketa and atskzeta but was unable to interact with the lrr-rlk. bctv c4 interaction with atsketa was confirmed using an in vitro binding assay. the protein kinases were capable of autophosphorylation i ... | 2007 | 17280695 |
| heterologous complementation by geminivirus al2 and al3 genes. | the geminivirus group is diverse and contains viruses which can be placed into three distinct subgroups on the basis of their genome organization and biological properties. however, most dicot-infecting gemiviruses possess al1, al2, and al3 open reading frames. al1 encodes the only viral protein that is absolutely required for replication, al2 codes for a protein that transactivates the expression of virion sense promoters, and al3 specifies a protein that enhances viral dna replication. in the ... | 1994 | 8053144 |
| proliferating cell nuclear antigen transcription is repressed through an e2f consensus element and activated by geminivirus infection in mature leaves. | the geminivirus tomato golden mosaic virus (tgmv) amplifies its dna genome in differentiated plant cells that lack detectable levels of dna replication enzymes. earlier studies showed that tgmv induces the accumulation of proliferating cell nuclear antigen (pcna), the processivity factor for dna polymerase delta, in mature cells of nicotiana benthamiana. we sought to determine if pcna protein accumulation reflects transcriptional activation of the host gene. rna gel blot analysis detected an app ... | 2001 | 11402171 |