| three-dimensional structure of satellite tobacco mosaic virus at 2.9 a resolution. | the crystal structure of satellite tobacco mosaic virus (stmv) has been solved by a combination of multiple isomorphous replacement and molecular replacement methods and refined at 2.9 a resolution to a conventional r-factor of 0.215. stmv, a t = 1 icosahedral virus, is the smallest whose structure has been determined. the coat protein is an eight-stranded "swiss roll" beta-barrel with an amino-terminal strand that extends away from the beta-barrel by more than 60 a. this strand is primarily res ... | 1993 | 8510153 |
| transfection of whole plants from wounds inoculated with agrobacterium tumefaciens containing cdna of tobacco mosaic virus. | we engineered cdna of tobacco mosaic tobamovirus (tmv) into agrobacterium tumefaciens for inoculation of plant cells. the resulting bacterial strains were used to transfect tobacco (nicotiana tabacum cv. xanthi and xanthi/nc) with wild type and a defective virus. lesion formation on xanthi/nc tobacco was used to measure the timing and efficiency of transfection. infections mediated by agrobacterium produced lesions an average of two days later than infections produced by inoculation with virions ... | 1993 | 8514842 |
| low level of genetic drift in foreign sequences replicating in an rna virus in plants. | the accumulation of mutations was measured in foreign sequences constituting a portion of a hybrid virus derived from the 6.4-kb (+) rna virus, tobacco mosaic tobamovirus (tmv). neither of the two foreign sequences tested (dihydrofolate reductase and neomycin phosphotransferase ii) are functionally required by the virus, so they should be free of selective pressures and should be a true measure of viral sequence drift in whole plants. four hybrid virus populations, two of each foreign sequence, ... | 1993 | 8517013 |
| analysis of a tobacco mosaic virus strain capable of overcoming n gene-mediated resistance. | the genome of ob, a tobamovirus that overcomes the n gene-mediated hypersensitive response (hr), was cloned as a cdna, and its nucleotide sequence was determined. the genomic organization of ob is similar to that of other tobamoviruses, consisting of 6506 nucleotides and containing at least four open reading frames. these open reading frames encode a 126-kd polypeptide with a 183-kd readthrough product, a 30.6-kd movement protein, and an 18-kd coat protein. a bacteriophage t7 promoter sequence w ... | 1993 | 8518557 |
| cysteine trnas of plant origin as novel uga suppressors. | we have isolated and sequenced chloroplast (chl) and cytoplasmic (cyt) cysteine trnas from nicotiana rustica. both trnas carry a gca anticodon but beyond that differ considerably in their nucleotide sequences. one obvious distinction resides in the presence of n6-isopentenyladenosine (i6a) and 1-methylguanosine (m1g) at position 37 in chl and cyt trna(cys) respectively. in order to study the potential suppressor activity of trnas(cys) we used in vitro synthesized zein mrna transcripts in which a ... | 1995 | 8524647 |
| multiple serine phosphorylation sites on the 30 kda tmv cell-to-cell movement protein synthesized in tobacco protoplasts. | p30, the protein required for cell-to-cell movement of tobacco mosaic virus (tmv), has a slightly reduced mobility on sds-polyacrylamide gels when isolated by immunoprecipitation from tmv-infected protoplasts compared with that of p30 translated from viral rna in vitro. further investigation established a probable cause for the difference in mobility between the two: protoplasts incorporate [32p]orthophosphate into p30 at multiple sites, predominantly as phosphoserine. tryptic peptide mapping re ... | 1995 | 8528282 |
| green-fluorescent protein as a new vital marker in plant cells. | the green-fluorescent protein (gfp) from jellyfish aequorea victoria has been used as a convenient new vital marker in various heterologous systems. however, it has been problematic to express gfp in higher eukaryotes, especially in higher plants. this paper reports that either a strong constitutive or a heat-shock promoter can direct the expression of gfp which is easily detectable in maize mesophyll protoplasts. in this single-cell system, bright green fluorescence emitted from gfp is visible ... | 1995 | 8528289 |
| cloning and properties of a rice gene encoding phenylalanine ammonia-lyase. | phenylalanine ammonia-lyase (pal) genomic sequences were isolated from a rice (oryza sativa l.) genomic library using a pcr-amplified rice pal dna fragment as a probe. there is a small family of pal genes in the rice genome. the nucleotide sequence of one pal gene, zb8, was determined. the zb8 gene is 4660 bp in length and consists of two exons and one intron. it encodes a polypeptide of 710 amino acids. the transcription start site was 137 bp upstream from the translation initiation site. rice ... | 1995 | 8534851 |
| assessment of the mutagenicity of extracts of tmv-coat-protein-gene induced transgenic tomato by the umu-test. | we examined the mutagenicity of extracts (juice and ethanol extract) from a transgenic tomato that was established by transfection of a gene encoding the coat protein of tobacco mosaic virus (tmv) to the f1 hybrid between lycopersicon esculentum la1000 and l. peruvianum pi128650, by the umu-test with salmonella typhimurium ta1535/psk1002 as the test organism. the extracts showed no detectable mutagenicity. the extracts from the above-mentioned f1 hybrids and wild tomatoes and cultivars (l. peruv ... | 1995 | 8541659 |
| [effect of synthesizing molecules of double-stranded rna in transgenic tobacco plants on resistance to tobacco mosaic virus]. | | 1993 | 8358319 |
| structural comparison of the plant satellite viruses. | detailed structures are now available for three plant satellite viruses, satellite tobacco necrosis virus (stnv), satellite tobacco mosaic virus (stmv), and satellite panicum mosaic virus (spmv). it is, therefore, possible to compare the tertiary structure of viral protein subunits, their quaternary interactions, and the interactions of protein subunits with the rna genome. this analysis indicates that, in spite of common function and preservation of a "jelly-roll" motif in the protein monomer, ... | 1995 | 8553559 |
| characterization of tobacco plants expressing a bacterial salicylate hydroxylase gene. | transgenic tobacco plants that express the bacterial nahg gene encoding salicylate hydroxylase have been shown to accumulate very little salicylic acid and to be defective in their ability to induce systemic acquired resistance (sar). in recent experiments using transgenic nahg tobacco and arabidopsis plants, we have also demonstrated that salicylic acid plays a central role in both disease susceptibility and genetic resistance. in this paper, we further characterize tobacco plants that express ... | 1995 | 8555459 |
| the coat protein of potato virus x is a strain-specific elicitor of rx1-mediated virus resistance in potato. | the rx1 gene in potato confers extreme resistance to potato virus x (pvx). to investigate the mechanism and elicitation of rx resistance, protoplasts of potato cv. cara (rx1 genotype) and maris bard (rx1 genotype) were inoculated with pvx and tobacco mosaic virus (tmv). at 24 h post-inoculation in maris bard protoplasts there was at least 100-fold more pvx rna than in protoplasts of cara. tmv rna accumulated to the same level in both types of protoplast. however, when the tmv was inoculated toge ... | 1995 | 8580963 |
| a ribozyme gene and an antisense gene are equally effective in conferring resistance to tobacco mosaic virus on transgenic tobacco. | ribozymes of the hammerhead class can be designed to cleave a target rna in a sequence-specific manner and can potentially be used to specifically modulate gene activity. we have targeted the tobacco mosaic virus (tmv) genome with a ribozyme containing three catalytic hammerhead domains embedded within a 1 kb antisense rna. the ribozyme was able to cleave tmv rna at all three target sites in vitro at 25 degrees c. transgenic tobacco plants were generated which expressed the ribozyme or the corre ... | 1996 | 8602148 |
| the pr-1a promoter contains a number of elements that bind gt-1-like nuclear factors with different affinity. | the 900 bp promoter region of the tobacco pr-1a gene was divided into eight fragments using pcr. the fragments were tested for their ability to bind to nuclear factors isolated from tobacco leaf. band shift assays demonstrated that all but one of the fragments specifically interacted with nuclear proteins. from competition experiments it was determined that the same nuclear factors bind various promoter fragments with different affinity. moreover, efficient competition with a synthetic tetramer ... | 1996 | 8605301 |
| mapping of the red clover necrotic mosaic virus subgenomic rna. | the red clover necrotic mosaic dianthovirus capsid protein is expressed in vivo from a subgenomic rna (sgrna) identical to the 3'-terminal 1.5 kb of rna-1. the 5' leader sequence of the capsid protein sgrna is 62 nucleotides, contains a 14-nucleotide putative promoter sequence homologous to the rna-1 5' terminus, and exhibits a high level of similarity with the tobacco mosaic virus 5' leader translational enhancer element omega. analysis of the rna-1 secondary structure, in the region adjacent t ... | 1996 | 8607270 |
| a central pseudoknotted three-way junction imposes trna-like mimicry and the orientation of three 5' upstream pseudoknots in the 3' terminus of tobacco mosaic virus rna. | a three-dimensional model of the histidylable 3'-terminal trna-like domain of tobacco mosaic virus rna is proposed on the basis of a comparative structural analysis, chemical and enzymatic probing, combined with graphical modeling of three rna constructs of increasing size (38, 108, and 182 nt) derived from the 3'-terminal viral rna sequence. the comparison between the probing patterns of the three rnas allowed the determination of the relative orientation of these structural domains in the full ... | 1996 | 8608444 |
| bidirectional uncoating of the genomic rna of a helical virus. | an essential step in the initiation of a virus infection is the release of the viral genome from the other constituents of the virus particle, a process referred to as uncoating. we have used reverse transcription and polymerase chain reaction amplification procedures to determine the rate and direction of in vivo uncoating of the rod-shaped tobacco mosaic virus. the virus particles contain a single 6.4-kb rna molecule that lies between successive turns of a helical arrangement of coat protein s ... | 1996 | 8610154 |
| movement of a barley stripe mosaic virus chimera with a tobacco mosaic virus movement protein. | the tobacco mosaic virus (tmv) 30k movement protein (mp) gene was inserted into a full-length cdna clone of barley stripe mosaic virus (bsmv) rna beta replacing the triple gene block (tgb). the resulting recombinant nd-mpt genome, consisting of infectious wt transcripts of bsmv rnas alpha and gamma, together with the hybrid rna beta transcript, was inoculated onto test plants to study the functional compatibility between the bsmv tgb-adapted genetic system and the tobamovirus transport gene. nd- ... | 1996 | 8610434 |
| comparison of the nucleic acid- and ntp-binding properties of the movement protein of cucumber mosaic cucumovirus and tobacco mosaic tobamovirus. | the cucumber mosaic virus (cmv) 3a movement protein (mp) was compared directly to the well-characterized tobacco mosaic virus (tmv) 30k mp by cloning the genes encoding these proteins into escherichia coli, isolating the e. coli-expressed mps, and characterizing them with regard to rna- and ntp-binding activities. the two mps were shown to bind single-stranded rna and dna cooperatively, but with no sequence specificity. however, discrete lengths of cmv rna 3 could be protected against rnase dige ... | 1996 | 8615008 |
| inhibition of a plant virus infection by analogs of melittin. | an approach that enables identification of specific synthetic peptide inhibitors of plant viral infection is reported. synthetic analogs of melittin that have sequence and structural similarities to an essential domain of tobacco mosaic virus coat protein were found to possess highly specific antiviral activity. this approach involves modification of residues located at positions analogous to those that are critical for virus assembly. the degree of inhibition found correlates well with sequence ... | 1995 | 8618922 |
| non-canonical translation mechanisms in plants: efficient in vitro and in planta initiation at auu codons of the tobacco mosaic virus enhancer sequence. | the 5' untranslated leader (omega sequence) of tobacco mosaic virus (tmv) genomic rna was utilized as a translational enhancer sequence in expression of the 17 kda putative movement protein (pr17) of potato leaf roll luteovirus (plrv). in vitro translation of rnas transcribed from appropriate chimeric constructs, as well as their expression in transgenic potato plants, resulted in the expected wild-type pr17 protein, as well as in larger translational products recognized by pr17-specific antiser ... | 1996 | 8628648 |
| mapping nucleotides in the 126-kda protein gene that control the differential symptoms induced by two strains of tobacco mosaic virus. | the differential symptom determinants of the holmes' masked (m) and u1 strains of tobacco mosaic virus previously were mapped to the 5'-coterminal open reading frame (orf) encoding the 126-kda protein and the n-terminal two-thirds of the 183-kda protein. both proteins influence viral rna accumulation, but the function of, and impact on, symptom formation by large domains within the 126-kda gene, which are not conserved with sequences in analogous orfs from other related viruses, are unknown. in ... | 1996 | 8661430 |
| isolation and characterization of the 102-kilodalton rna-binding protein that binds to the 5' and 3' translational enhancers of tobacco mosaic virus rna. | tobacco mosaic virus (tmv) is a positive-sense, single-stranded rna virus the genome of which acts as a mrna in the cytoplasm. on infection, tmv mrna is efficiently and selectively translated by the host translation machinery despite the lack of a poly(a) tail, which is normally required for efficient translation. both the 68-base 5' leader (omega) and the 205-base 3' untranslated region of tmv promote efficient translation. a 25-base poly(caa) region within omega and the upstream pseudoknot dom ... | 1996 | 8663059 |
| the polymerase-like core of brome mosaic virus 2a protein, lacking a region interacting with viral 1a protein in vitro, maintains activity and 1a selectivity in rna replication. | brome mosaic virus (bmv), a member of the alphavirus-like super-family of positive-strand rna viruses, encodes two proteins required for viral rna replication: 1a and 2a. 1a contains m7g methyltransferase- and helicase-like domains, while 2a contains a polymerase (pol)-like core flanked by n- and c-terminal extensions. genetic studies show that bmv rna replication requires 1a-2a compatibility implying direct or indirect 1a-2a interaction in vivo. in vitro, la interacts with the n-terminal 125-am ... | 1996 | 8676500 |
| complete nucleotide sequence and synthesis of infectious in vitro transcripts from a full-length cdna clone of a rakkyo strain of tobacco mosaic virus. | the complete nucleotide sequence of the genome of a rakkyo strain of tobacco mosaic virus (tmv-r), which exhibits distinct host range differences from the common strain of tmv, was determined. the overall nucleotide sequence homology with tmv-u1 (a common strain of tmv) is 94.2%. the amino acid sequence homologies of the four encoded proteins (180k, 130k, 30k, coat protein) are from 95.9% to 98.0% compared with tmv-u1. to facilitate the analysis of the novel host range of tmv-r, a full-length cl ... | 1996 | 8678834 |
| a mammalian 2-5a system functions as an antiviral pathway in transgenic plants. | resistance to virus infections in higher vertebrates is mediated in part through catalysis of rna decay by the, interferon-regulated 2-5a system. a functional 2-5a system requires two enzymes, a 2-5a synthetase that produces 5'-phosphorylated, 2',5'-linked oligoadenylates (2-5a) in response to double-stranded rna, and the 2-5a-dependent rnase l. we have coexpressed these human enzymes in transgenic tobacco plants by using a single plasmid containing the cdnas for both human rnase l and a low mol ... | 1996 | 8692895 |
| expression of the green fluorescent protein-encoding gene from a tobacco mosaic virus-based vector. | a cdna fragment encompassing the aequorea victoria green fluorescent protein-encoding gene (gfp) was introduced into a genomic cdna clone of tobacco mosaic virus (tmv). infectious rna transcripts produced in vitro were used to inoculate tobacco (nicotiana benthamiana) leaves. after 1-2 days, bright green fluorescent areas could be visualized upon illumination with a long-wave ultraviolet (uv) light source. the virus was capable of infecting and expressing gfp in plant tissues both locally (in th ... | 1996 | 8707059 |
| complete replication in vitro of tobacco mosaic virus rna by a template-dependent, membrane-bound rna polymerase. | a crude membrane-bound rna polymerase, obtained by differential centrifugation of extracts of tomato leaves infected with tobacco mosaic tobamovirus (tomato strain l) tmv-l), was purified by sucrose density gradient centrifugation. removal of the endogenous rna template with micrococcal nuclease rendered the polymerase template dependent and template specific. the polymerase was primer independent and able to initiate rna synthesis on templates containing the 3'-terminal sequences of the tmv-l p ... | 1996 | 8709249 |
| the 126- and 183-kilodalton proteins of tobacco mosaic virus, and not their common nucleotide sequence, control mosaic symptom formation in tobacco. | nucleotide substitutions at two positions within the open reading frame encoding the 126-kda protein in the attenuated masked (m) strain of tobacco mosaic tobamovirus (tmv) to those found in the virulent u1-tmv genome led to the induction of near u1-tmv-like symptoms on leaves of nicotiana tabacum l. cv. xanthi nn by progeny virus (m. h. shintaku, s. a. carter, y. bao, and r. s. nelson, virology 221:218-225, 1996). in this study, further site-directed mutations were made at these positions withi ... | 1996 | 8709266 |
| the n gene of tobacco confers resistance to tobacco mosaic virus in transgenic tomato. | it has been proposed that cloned plant disease resistance genes could be transferred from resistant to susceptible plant species to control important crop plant diseases. the recently cloned n gene of tobacco confers resistance to the viral pathogen, tobacco mosaic virus. we generated transgenic tomato plants bearing the n gene and demonstrate that n confers a hypersensitive response and effectively localizes tobacco mosaic virus to sites of inoculation in transgenic tomato, as it does in tobacc ... | 1996 | 8710948 |
| [construction and analysis of transgenic plants of nicotiana tabacum l. expressing a bacterial gene for beta-1,3-glucanase. ii. transgenic tobacco plants expressing the bacterial beta-glucanase gene from clostridium thermocellum,--a model for studying the differential expression of stress response-related genes]. | the modified hybrid beta-1,3-glucanase gene (glc) of clostridium thermocellum was expressed in tobacco nicotiana tabacum. the glc gene was cloned into two plasmids, pc27-glc and pc29-glc, in which its expression was controlled by the tr2' promoter of the 2' gene of t-dna and the rbcs promoter of arabidopsis, respectively. these constructions were used for transformation of agrobacteria followed by transfer into plants. in transformed plants, each plasmid caused a high level of activity of thermo ... | 1996 | 8713621 |
| tobacco mosaic virus movement protein-mediated protein transport between trichome cells. | tobacco mosaic virus movement protein (tmv mp) is required to mediate viral spread between plant cells via plasmodesmata. plasmodesmata are cytoplasmic bridges that connect individual plant cells and ordinarily limit molecular diffusion to small molecules and metabolites with a molecular mass up to 1 kd. here, we characterize functional properties of nicotiana clevelandii trichome plasmodesmata and analyze their interaction with tmv mp. trichomes constitute a linear cellular system and provide a ... | 1995 | 8718620 |
| tobacco mosaic virus movement protein associates with the cytoskeleton in tobacco cells. | tobacco mosaic virus movement protein p30 complexes with genomic viral rna for transport through plasmodesmata, the plant intercellular connections. although most research with p30 focuses on its targeting to and gating of plasmodesmata, the mechanisms of p30 intracellular movement to plasmodesmata have not been defined. to examine p30 intracellular localization, we used tobacco protoplasts, which lack plasmodesmata, for transfection with plasmids carrying p30 coding sequences under a constituti ... | 1995 | 8718621 |
| efficient promoter cassettes for enhanced expression of foreign genes in dicotyledonous and monocotyledonous plants. | a series of chimeric promoters for higher-level expression of foreign genes in plants was constructed as fusions of a gene for beta-glucuronidase (gus) with the terminator of a gene for nopaline synthase (nos) or of the cauliflower mosaic virus (camv) 35s transcript, and the strength of these promoters was assayed in transient and stable expression systems in tobacco and rice. as parts of these promoters, the camv 35s core promoter, three different 5'-upstream sequences of the 35s promoter, the ... | 1996 | 8720924 |
| comparative interaction kinetics of two recombinant fabs and of the corresponding antibodies directed to the coat protein of tobacco mosaic virus. | two recombinant fab fragments, 57p and 174p, recognizing peptide 134-146 of the coat protein of tobacco mosaic virus have been cloned, sequenced and expressed in escherichia coli. they differ by 15 amino acid changes in the sequence of their variable region. the interaction kinetics of the fabs with the wild-type and four mutant peptides have been compared using a biacoretm biosensor instrument. the recombinant fab 174p had the same reactivity as the fab fragment obtained by enzymatic cleavage o ... | 1996 | 8723318 |
| electron holographic observation for biological specimens: electron holography of bio-specimens. | electron holography has been applied to the observation of biological filaments. the technique has some advantages over conventional imaging for observing weak-phase objects such as small unstained biological structures. to avoid artificial structural transformation of the sample owing to the interaction with the supporting film, a holey carbon film was used to support the filaments. a tobacco mosaic virus bridged over a hole was observed as a cylindrical shape; the contrast distribution across ... | 1996 | 8763170 |
| vertical dimension of hydrated biological samples in tapping mode scanning force microscopy. | the vertical dimensions of the well-characterized test samples tobacco mosaic virus, t4 bacteriophage polyhead, purple membrane, and hexagonally packed intermediate (hpi) layer were investigated by tapping mode scanning force microscopy (sfm) in solution. purple membrane and hpi layer were imaged in both contact mode and tapping mode sfm for direct comparison. all vertical dimensions match the known heights. the practical implications of the absence of frictional forces in tapping mode are discu ... | 1996 | 8785308 |
| the complete nucleotide sequence of odontoglossum ringspot virus (cy-1 strain) genomic rna. | the complete nucleotide sequence of the genomic rna of odontoglossum ringspot virus cy-1 strain (orsv cy-1) was determined using cloned cdna. this sequence is 6611 nucleotides long containing four open reading frames, which correspond to 126 k, 183 k, 31 k, and 18 k proteins. its genomic organization is similar to other tobamoviruses, tmv-v(vulgare), tmv-l (tomato strain), tobacco mild green mosaic virus (tmgmv) and cucumber green mottle mosaic virus (cgmmv). the 5' non-coding regions of orsv cy ... | 1995 | 8789059 |
| mass spectrometry and viral analysis. | electrospray ionization (esi) mass spectrometry is a powerful new approach for analyzing biomolecules and biomolecular complexes. previous studies have provided evidence that non-covalent biomolecular complexes can be observed by esi mass spectrometry; it is not clear, however, whether the native conformation of the biomolecules is maintained throughout the ionization and analysis process. we set out to address this question using live viruses. | 1996 | 8807827 |
| molecular cloning of a metallothionein-like gene from nicotiana glutinosa l. and its induction by wounding and tobacco mosaic virus infection. | the cloning and characterization of genes expressed in plant disease resistance could be an initial step toward understanding the molecular mechanisms of disease resistance. a metallothionein-like gene that is inducible by tobacco mosaic virus and by wounding was cloned in the process of subtractive cloning of disease resistance-response genes in nicotiana glutinosa. one 530-bp cdna clone (kc9-10) containing an open reading frame of 81 amino acids was characterized. genomic southern blot hybridi ... | 1996 | 8819331 |
| incorporation of microcrystals by growing protein and virus crystals. | in the course of time-lapse video and atomic force microscopy (afm) investigations of macromolecular crystal growth, we frequently observed the sedimentation of microcrystals and three-dimensional nuclei onto the surfaces of much larger, growing protein or virus crystals. this was followed by the direct incorporation over time of the smaller crystals into the bulk of the larger crystals. in some cases, clear indications were present that upon absorption of the small crystal onto the surface of t ... | 1996 | 8820491 |
| differences in the subcellular localization of tobacco mosaic virus and cucumber mosaic virus movement proteins in infected and transgenic plants. | our study reveals differences in the way that tobacco mosaic virus (tmv) and cucumber mosaic virus (cmv) movement proteins (mps) partition with cellular components separated into four fractions from different aged leaves of infected and transgenic plants. immunoblot analyses showed that tmv and cmv mps associated predominantly with components in the cell wall fractions from leaves of transgenic plants. in infected tissue, highest levels of tmv mp were found in the organelle fractions from young ... | 1995 | 8847533 |
| invasion of minor veins of tobacco leaves inoculated with tobacco mosaic virus mutants defective in phloem-dependent movement. | to fully understand vascular transport of plant viruses, the viral and host proteins, their structures and functions, and the specific vascular cells in which these factors function must be determined. we report here on the ability of various cdna-derived coat protein (cp) mutants of tobacco mosaic virus (tmv) to invade vascular cells in minor veins of nicotiana tabacum l. cv. xanthi nn. the mutant viruses we studied, tmv cp-o, u1mcp15-17, and snc015, respectively, encode a cp from a different t ... | 1996 | 8855325 |
| expression of class i o-methyltransferase in healthy and tmv-infected tobacco. | tobacco possesses two distinct classes of o-methyltransferases (omts; s-adenosyl-l-methionine:o-diphenol o-methyltransferases; ec 2.1.1.6). here we report on the cloning and the expression pattern of the class i omt that is specifically involved in lignin biosynthesis. near-full-length cdnas have been isolated from tobacco libraries constructed from leaf and stem poly(a)+ rna. sequence analysis demonstrated that the omt i clones derived from two different mrna species. the two types of omt i mrn ... | 1996 | 8870267 |
| teaching light scattering spectroscopy: the dimension and shape of tobacco mosaic virus. | the tobacco mosaic virus is used as a model molecular assembly to illustrate the basic potentialities of light scattering techniques (both static and dynamic) to undergraduates. the work has two objectives: a pedagogic one (introducing light scattering to undergraduate students) and a scientific one (stabilization of the virus molecular assembly structure by the nucleic acid). students are first challenged to confirm the stabilization of the cylindrical shape of the virus by the nucleic acid, at ... | 1996 | 8874039 |
| viral rna trafficking is inhibited in replicase-mediated resistant transgenic tobacco plants. | transgenic tobacco (nicotiana tabacum cv. turkish samsun nn) plants expressing a truncated replicase gene sequence from rna-2 of strain fny of cucumber mosaic virus (cmv) are resistant to systemic cmv disease. this is due to suppression of virus replication and cell-to-cell movement in the inoculated leaves of these plants. in this study, microinjection protocols were used to directly examine cell-to-cell trafficking of cmv viral rna in these resistant plants. cmv rna fluorescently labeled with ... | 1996 | 8901636 |
| carboxylate interactions involved in the disassembly of tobacco mosaic tobamovirus. | structural studies of tobacco mosaic tobamovirus (tmv) have identified two coat protein (cp) intersubunit carboxyl-carboxylate interactions and one cp carboxylate-rna phosphate interaction whose electrostatic repulsion is believed to drive virion disassembly. in this study, the involvement of each interaction in the disassembly process was examined. site-directed mutagenesis was used to replace selected negatively charged cp residues, e or d, with neutral residues, q or n, respectively. purified ... | 1996 | 8918529 |
| long pcr and its application to hepatitis viruses: amplification of hepatitis a, hepatitis b, and hepatitis c virus genomes. | in this study we amplified virtually the entire genomes of hepatitis a virus (a member of the picornaviridae family), hepatitis b virus (a member of the hepadnaviridae family), and hepatitis c virus (a member of the flaviviridae family) by using the recently described technique of long pcr. in order to do this, we first demonstrated, using the lambda phage, that long pcr can be made highly sensitive and the sensitivity can be further enhanced by nested long pcr. we also showed, using tobacco mos ... | 1996 | 8940452 |
| functional mapping of conserved residues located at the vl and vh domain interface of a fab. | the interface between the vl and vh domains of antibodies is highly conserved. to investigate the influence of conserved interface residues on fab function, 13 interface residues were subjected to codon-based combinatorial alanine scanning mutagenesis in fab 57p, specific for peptide 134 to 151 of the coat protein of tobacco mosaic virus. the 13 single mutants were analysed by western blot to determine the effect of interface modifications on fab expression. the kinetic rate constants of peptide ... | 1996 | 8950262 |
| mapping of host range restriction of the rakkyo strain of tobacco mosaic virus in nicotiana tabacum cv. bright yellow. | the rakkyo strain (tmv-r) and the common strain (tmv-u1) of tobacco mosaic virus exhibit distinct host range differences. tmv-r infects rakkyo plants, a monocot host that tmv-u1 is unable to infect. however, tmv-r causes only latent infection in nicotiana tabacum cv. bright yellow (by) in inoculated leaves, whereas tmv-u1 infects by systemically and induces mosaic symptoms. complete nucleotide sequencing of the tmv-r genomic rna revealed amino acid changes in the 130k/ 180k replicase proteins, t ... | 1996 | 8955039 |
| tobamovirus cross protection using a potexvirus vector. | cross protection is the ability of one virus to prevent or delay infection by a related challenge virus. to examine this phenomena, a potato x potexvirus (pvx) vector (chapman et al., 1992, plant j. 2, 549) was used to systemically express the tobacco mosaic tobamovirus (tmv) coat protein (cp) open reading frame in nicotiana benthamiana. pvx constructs induce mild mosaic symptoms in n. benthamiana, whereas tmv infection results in rapid systemic necrosis and plant death. healthy plants or plants ... | 1996 | 8955042 |
| pathogenesis-related functions of plant beta-1,3-glucanases investigated by antisense transformation--a review. | plant beta-1,3-glucanases (beta glu) have been implicated in several physiological and developmental processes, e.g., cell division, microsporogenesis, pollen germination, fertilization and seed germination. these enzymes, particularly the antifungal class-i vacuolar isoforms, are also believed to be part of the defences of plants against fungal infection. the function of beta glu in tobacco and nicotiana sylvestris has been investigated by antisense transformation. transformation with gla, the ... | 1996 | 8955634 |
| isolation and characterization of a tobacco mosaic virus-inducible myb oncogene homolog from tobacco. | salicylic acid (sa) plays an important role in signaling the activation of plant defense responses against pathogen attack including induction of pathogenesis-related (pr) proteins. to gain further insight into the sa-mediated signal transduction pathway, we have isolated and characterized a tobacco mosaic virus (tmv)-inducible myb oncogene homolog (myb1) from tobacco. the myb1 gene was induced upon tmv infection during both the hypersensitive response and development of systemic acquired resist ... | 1996 | 8962166 |
| [modification of tobacco mosaic virus envelope protein using trinitrobenzenesulfonic acid]. | the process of modification of tobacco mosaic virus (tmv) coat protein with a lysine-specific reagent trinitrobenzenesulfonic acid (tnbs) was studied. tmv coat protein molecule is known to contain just two lys residues (k53 and k68) localized in the same region of tmv coat protein subunit tertiary structure at a distance of about 70ao from the virion axis. tnbs was used to modify the coat protein of wild type (u1) tmv and that of a coat protein ts-mutant ts21-66, bearing two amino-acid substitut ... | 1996 | 8999317 |
| identification of a salicylic acid-responsive element in the promoter of the tobacco pathogenesis-related beta-1,3-glucanase gene, pr-2d. | the tobacco pathogenesis-related pr-2d gene encodes an acidic beta-1,3-glucanase. expression of the pr-2d: uida(gus) chimeric gene is induced in leaves undergoing the hypersensitive resistance response to tobacco mosaic virus and after treatment with salicylic acid (sa), a chemical believed to play an important role(s) in disease resistance. we have constructed transgenic tobacco plants which carry various segments of the pr-2d promoter fused to a heterologous core 35s promoter driving the uida( ... | 1996 | 9011089 |
| modeling supra-molecular helices: extension of the molecular surface recognition algorithm and application to the protein coat of the tobacco mosaic virus. | geometric matching of molecular surfaces appears to be essential for the formation of binary molecular complexes and of supra-molecular aggregates. the structure of a binary complex is characterized by the best geometric match, whereas the structure of an aggregate is characterized by the best combined match, i.e. the sum of all the internal matches in the system. we describe a method to identify and quantify the binary matches between molecules and then use them to form the supra-molecular heli ... | 1997 | 9054976 |
| properties of the coat protein of a new tobacco mosaic virus coat protein ts-mutant. | amino acid substitutions in a majority of tobacco mosaic virus (tmv) coat protein (cp) ts-mutants have previously been mapped to the same region of the cp molecule tertiary structure, located at a distance of about 70 a from tmv virion axis. in the present work some properties of a new tmv cp ts-mutant ts21-66 (two substitutions i21=>t and d66=>g, both in the 70-a region) were studied. thermal inactivation characteristics, sedimentation properties, circular dichroism spectra, and modification by ... | 1997 | 9055205 |
| structural analysis of a-protein of cucumber green mottle mosaic virus and tobacco mosaic virus by synchrotron small-angle x-ray scattering. | the size and shape of a-protein of tobacco mosaic virus coat protein (tmvp) and cucumber green mottle mosaic virus coat protein (cgmmvp) were evaluated by means of small-angle x-ray scattering (saxs) using a synchrotron radiation source, complemented by electron microscopic observations. the results imply that tmv and cgmmv a-proteins are composed of three and two subunits, respectively, stacked in the shape of an isosceles triangular prism at lower ionic strength. considering the difference of ... | 1997 | 9112608 |
| a novel inhibitor of cap-dependent translation initiation in yeast: p20 competes with eif4g for binding to eif4e. | in the yeast saccharomyces cerevisiae a small protein named p20 is found associated with translation initiation factor eif4e, the mrna cap-binding protein. we demonstrate here that p20 is a repressor of cap-dependent translation initiation. p20 shows amino acid sequence homology to a region of eif4g, the large subunit of the cap-binding protein complex eif4f, which carries the binding site for eif4e. both, eif4g and p20 bind to eif4e and compete with each other for binding to eif4e. the eif4e-p2 ... | 1997 | 9118949 |
| nontranslatability and dissimilar behavior in plants and protoplasts of viral rna and movement protein complexes formed in vitro. | it was found that the fusion (his)6-movement proteins (mps) of two tobamoviruses (tmv ui and a crucifer-infecting tobamovirus, crtmv) were efficient nonspecific translational repressors. the in vitro translation of viral rnas was blocked by incomplete 30k mp-rna complexes formed at the mp:rna molar ratios of 100-150:1. similar results were obtained with the barley stripe mosaic hordeivirus (bsmv)-encoded 58k mp; however, the translation inhibiting activity of the 58k mp was manifested only in th ... | 1997 | 9126258 |
| characterization of chimeric turnip yellow mosaic virus genomes that are infectious in the absence of aminoacylation. | previous experiments have characterized the chimeric genome tymc-tmvpsk, in which the 3'-trna-like structure of turnip yellow mosaic virus (tymv) was replaced by 3' sequences from tobacco mosaic virus. this genome accumulated in turnip protoplasts to a level about 3% of wild type, but was not infectious on plants. in the present study, tymv sequences introduced into the anticodon loop and amino acid acceptor arm of the 3' region of this chimera led to three- to fourfold increases in viral accumu ... | 1997 | 9126267 |
| molecular resolution imaging of macromolecular crystals by atomic force microscopy. | atomic force microscopy (afm) images at the molecular level have been obtained for a number of different protein and virus crystals. they can be utilized in some special cases to obtain information useful to crystal structure analyses by x-ray diffraction. in particular, questions of space group enantiomer, the packing of molecules within a unit cell, the number of molecules per asymmetric unit, and the dispositions of multiple molecules within the asymmetric unit may be resolved. in addition, b ... | 1997 | 9129839 |
| manipulation of individual viruses: friction and mechanical properties. | we present our results on the manipulation of individual viruses using an advanced interface for atomic force microscopes (afms). we show that the viruses can be dissected, rotated, and translated with great facility. we interpret the behavior of tobacco mosaic virus with a mechanical model that makes explicit the competition between sample-substrate lateral friction and the flexural rigidity of the manipulated object. the manipulation behavior of tobacco mosaic virus on graphite is shown to be ... | 1997 | 9138585 |
| a camv 35s promoter driven cdna clone of tobacco mosaic virus can infect host plant tissue despite being uninfectious when manually inoculated onto leaves. | leading from the success of inoculating plants with viral rna transcribed in vitro from full length cdna clones, attempts have been made to build cdna clones which are directly infectious by inoculation. however, we and others have found that viral cdna clones driven by the camv 35s promoter were able to infect some host plants yet not others, when manually inoculated onto leaves. alternative methods including microprojectile bombardment have been used to deliver an infectious tmv construct into ... | 1997 | 9155883 |
| antigens produced in plants by infection with chimeric plant viruses immunize against rabies virus and hiv-1. | the coat protein (cp) of alfalfa mosaic virus was used as a carrier molecule to express antigenic peptides from rabies virus and hiv. the antigens were separately cloned into the reading frame of alfalfa mosaic virus cp and placed under the control of the subgenomic promoter of tobacco mosaic virus cp in the 30brz vector. the in vitro transcripts of recombinant virus with sequences encoding the antigenic peptides were synthesized from dna constructs and used to inoculate tobacco plants. the plan ... | 1997 | 9159151 |
| second-site reversion of a dysfunctional mutation in a conserved region of the tobacco mosaic tobamovirus movement protein. | the n-terminal two-thirds of tobamovirus movement proteins (mps) contain two well conserved regions. within region i (amino acids 56-96) is an area predicted by computer analysis to have loop secondary structure (amino acids 76-87). a single or two double amino acid mutations were introduced into the loop in region i of the tmv mp to destabilize the structure. the three mutant mps were defective in movement function. the single amino acid mutation resulted in a pro81-->ser substitution. the muta ... | 1997 | 9185584 |
| cooperative effects of mutations in a recombinant fab on the kinetics of antigen binding. | recombinant fabs, 57p and 174p, recognizing peptide 134-151 of the coat protein of tobacco mosaic virus, differ by 15 amino acid changes in the sequence of their variable region. kinetic analysis using biacore showed that they recognized five peptide variants in the same ranking order, but that fab 174p consistently dissociated faster from the peptides compared to fab 57p. in order to identify amino acid substitutions that are responsible for differences in dissociation rates of the two fabs, si ... | 1997 | 9188849 |
| replication of wild-type and mutant clones of satellite tobacco mosaic virus in nicotiana benthamiana protoplasts. | rna transcribed from cloned satellite tobacco mosaic virus (stmv) cdna replicated in nicotiana benthamiana protoplasts when co-inoculated with tobacco mild green mosaic virus (tmgmv) genomic rna, but degraded when inoculated alone. stmv genomic rna extracted from wild-type virions replicated in protoplasts when co-inoculated with tmgmv, tobacco mosaic virus (tmv) or tomato mosaic virus (tomv). transcripts from clones of two stmv coat protein (cp) mutants accumulated to the same level as wild-typ ... | 1997 | 9191918 |
| development of necrosis and activation of disease resistance in transgenic tobacco plants with severely reduced catalase levels. | numerous studies argue that salicylic acid (sa) is an important component of the plant signal transduction pathway(s) leading to disease resistance. the discovery that the sa-binding protein is a catalase, whose activity is blocked by sa, led to the proposal that one of sa's modes of action is to inhibit this h2o2-degrading enzyme and thus elevate h2o2 levels. to test this model, an attempt was made to mimic the action of sa by reducing the synthesis of catalase using antisense rna technology. a ... | 1997 | 9193071 |
| pathogen-induced programmed cell death in tobacco. | sacrificing an infected cell or cells in order to prevent systemic spread of a pathogen appears to be a conserved strategy in both plants and animals. we studied some of the morphological and biochemical events that accompany programmed cell death during the hypersensitive response of tobacco plants infected with tobacco mosaic virus. certain aspects of this cell death process appeared to be similar to those that take place during apoptosis in animal cells. these included condensation and vacuol ... | 1997 | 9202394 |
| two pr-1 genes from tomato are differentially regulated and reveal a novel mode of expression for a pathogenesis-related gene during the hypersensitive response and development. | pathogenesis-related (pr) proteins form a heterogeneous family of plant proteins that are likely to be involved in defense and are inducible by pathogen attacks. one group of prs, represented by the subfamily pr-1, are low-molecular-weight proteins of unknown biochemical function. here we describe the cloning and characterization of two closely related genes encoding a basic and an acidic pr-1 protein (pr1b1 and pr1a2) from tomato (lycopersicon esculentum). we present a comparative study of the ... | 1997 | 9204567 |
| characterization of nuclease activities and dna fragmentation induced upon hypersensitive response cell death and mechanical stress. | programmed cell death (pcd) is activated during the response of multicellular organisms to some invading pathogens. one of the key aspects of this process is the degradation of nuclear dna which is thought to facilitate the recycling of dna from dead cells. the pcd of tobacco plants (genotype nn) infected with tobacco mosaic virus (tmv) is accompanied by the induction of nuclease activities and the cleavage of nuclear dna to fragments of about 50 kb. we examined the correlation between the incre ... | 1997 | 9207837 |
| plant viral synergism: the potyviral genome encodes a broad-range pathogenicity enhancer that transactivates replication of heterologous viruses. | synergistic viral diseases of higher plants are caused by the interaction of two independent viruses in the same host and are characterized by dramatic increases in symptoms and in accumulation of one of the coinfecting viruses. in potato virus x (pvx)/potyviral synergism, increased pathogenicity and accumulation of pvx are mediated by the expression of potyviral 5' proximal sequences encoding p1, the helper component proteinase (hc-pro), and a fraction of p3. here, we report that the same potyv ... | 1997 | 9212462 |
| actions of pokeweed antiviral protein on virus-infected protoplasts. | pokeweed antiviral protein (pap) belongs to a group of ribosome-inactivating proteins (rips) that inactivate ribosomes by depurinating rrna at a specific site. to study the mechanism for the antiviral activity of pap, the actions of pap on tmv-infected and uninfected tobacco protoplasts were investigated. the addition of 0.33 microm pap to tmv-inoculated protoplasts caused a complete inhibition of tmv production. the same concentration of pap was found to inhibit protein synthesis in the virus-i ... | 1997 | 9214760 |
| strategy for rna recognition by yeast histidyl-trna synthetase. | histidine aminoacylation systems are of interest because of the structural diversity of the rna substrates recognized by histidyl-trna synthetases. among trnas participating in protein synthesis, those specific for histidine all share an additional residue at their 5'-extremities. on the other hand, trna-like domains at the 3'--termini of some plant viruses can also be charged by histidyl-trna synthetases, although they are not actors in protein synthesis. this is the case for the rnas from toba ... | 1997 | 9222493 |
| the tobacco mosaic virus rna polymerase complex contains a plant protein related to the rna-binding subunit of yeast eif-3. | a sucrose density gradient-purified, membrane-bound tobacco mosaic virus (tomato strain l) (tmv-l) rna polymerase containing endogenous rna template was efficiently solubilized with sodium taurodeoxycholate. solubilization resulted in an increase in the synthesis of positive-strand, 6.4-kb genome-length single-stranded rna (ssrna) and a decrease in the production of 6.4-kbp double-stranded rna (dsrna) to levels close to the limits of detection. the solubilized tmv-l rna polymerase was purified b ... | 1997 | 9223501 |
| transgenic accumulation of two plant virus coat proteins on a single self-processing polypeptide. | an expression cassette based on the highly specific tobacco etch potyvirus (tev) nuclear inclusion (nia) proteinase has been developed to produce multiple proteins through the translation of a single self-processing polypeptide. gene constructs encoding tev nia, the tobacco mosaic tobamovirus (tmv) coat protein (cp) and the soybean mosaic potyvirus (smv) cp were used to develop transgenic tobacco plants. proper processing of the multifunctional polypeptide was demonstrated, leading to accumulati ... | 1997 | 9225054 |
| induction of antibodies to plant viral proteins by dna-based immunization. | dna-based immunization is a promising new technique for generating antibodies in laboratory animals for diagnostic purposes in biological science. the main advantages are the elimination of time and labor and the technically demanding steps of antigen purification. the dna sequence of the protein of interest, cloned in a suitable in vivo expression vector that is administered intramuscularly or intradermally, is sufficient to induce an immune response in animals. we report the induction of antib ... | 1997 | 9255730 |
| resistance to tobamoviruses in transgenic tobacco plants expressing the coat protein gene of pepper mild mottle virus (korean isolate). | red pepper, one of the most important vegetable crops in korea, is severely affected by viral diseases causing 20-50% reduction in product yield. a pepper strain of tobacco mosaic virus (tmv-p) is the most common virus in red pepper. to study the molecular structure of the tmv-p virus, we generated cdna clones of the viral genome. partial sequencing of a few cdna clones revealed that tmv-p shares a 98% identity at the nucleotide level with the spanish isolate of pepper mild mottle virus (pmmv-s) ... | 1997 | 9264016 |
| ultrastructural analysis of leaf trichome plasmodesmata reveals major differences from mesophyll plasmodesmata. | functional studies on molecular transport through plasmodesmata in leaf mesophyll and trichome cells revealed significant differences in their basal size-exclusion limits and their response to microinjected tobacco mosaic virus movement protein (e. waigmann et al., 1994, proc. natl. acad. sci. usa 91: 1433-1437; e. waigmann and p. zambryski, 1995, plant cell 7; 2069-2079). to address the basis for these functional differences, nicotiana clevelandii trichome and mesophyll plasmodesmata were compa ... | 1997 | 9299792 |
| studies of coat protein-mediated resistance to tobacco mosaic tobamovirus: correlation between assembly of mutant coat proteins and resistance. | coat protein-mediated resistance (cp-mr) has been widely used to protect transgenic plants against virus diseases. to characterize the mechanisms of cp-mr to tobacco mosaic tobamovirus (tmv) we developed mutants of the coat protein that affected subunit-subunit interactions. mutant cps were expressed during tmv replication as well as in transgenic nicotiana tabacum plants. the mutation t42-->w increased protein aggregation and t28-->w abolished aggregation and assembly, while the mutations t28-- ... | 1997 | 9311885 |
| involvement of proteasomal subunits zeta and iota in rna degradation. | we have identified two distinct subunits of 20 s proteasomes that are associated with rnase activity. proteasome subunits zeta and iota, eluted from two-dimensional western blots, hydrolysed tobacco mosaic virus rna, whereas none of the other subunits degraded this substrate under the same conditions. additionally, proteasomes were dissociated by 6 m urea, and subunit zeta, containing the highest rnase activity, was isolated by anion-exchange chromatography and gel filtration. purified subunit z ... | 1997 | 9337855 |
| a ribosome-inactivating protein from amaranthus viridis. | an antiviral protein purified from the leaves of amaranthus viridis was named amaranthin. the in vivo antiviral activity of amaranthin was confirmed in tobacco mosaic virus (tmv) infection test on nicotiana glutinosa leaves. the molecular mass of the amaranthin was estimated about 30 kda by sds-page and the pi was measured as 9.8 by isoelectric focusing (ief) analysis. cytotoxicity of the amaranthin using in vitro translation inhibition assay was similar to that of pokeweed antiviral protein (pa ... | 1997 | 9339569 |
| a century of tobamovirus evolution in an australian population of nicotiana glauca. | the evolution over the past century of two tobamoviruses infecting populations of the immigrant plant nicotiana glauca in new south wales (nsw), australia, has been studied. this plant species probably entered australia in the 1870s. isolates of the viruses were obtained from n. glauca specimens deposited in the nsw herbarium between 1899 and 1972, and others were obtained from living plants in 1985 and 1993. it was found that the nsw n. glauca population was infected with tobacco mosaic tobamov ... | 1997 | 9343184 |
| manipulation and trapping of sub-micron bioparticles using dielectrophoresis. | a non-uniform alternating electric field induces motion in polarisable particles called dielectrophoresis. the effect is governed by the relative magnitudes of the dielectric properties of the medium and the particles. the technology has been used to manipulate particles for biotechnological applications, including purification, fractionation and concentration of cells and microorganisms. however, the lower size limit for the dielectrophoretic manipulation of particles was believed to be about 1 ... | 1997 | 9350515 |
| gating of epidermal plasmodesmata is restricted to the leading edge of expanding infection sites of tobacco mosaic virus (tmv). | plasmodesmatal gating in epidermal cells of nicotiana tabacum was examined in expanding infection sites of tobacco mosaic virus (tmv) expressing a fusion between the viral movement protein and the green fluorescent protein (mp-gfp). the infection sites were circular in profile and within 3 days post-inoculation had developed a brightly fluorescent leading edge, giving them a characteristic 'halo' shape. co-localization of mp-gfp with callose demonstrated that nearly all epidermal cell plasmodesm ... | 1997 | 9375392 |
| opposite effects of electrostatics and steric exclusion on bundle formation by f-actin and other filamentous polyelectrolytes. | a number of positively charged polypeptides and proteins bundle dna, f-actin, microtubules, and viruses such as filamentous phage fd and tobacco mosaic virus (tmv), as well as intermediate filaments formed by vimentin. the general behavior is dictated by the common polyelectrolyte nature of these biopolymers, which gives rise to nonspecific binding by ligands carrying several net opposite charges. an attractive interaction accounts for the subsequent lateral aggregation, distinguishing this tran ... | 1997 | 9376366 |
| expression of a luteoviral movement protein in transgenic plants leads to carbohydrate accumulation and reduced photosynthetic capacity in source leaves. | elucidating the role of viral genes in transgenic plants revealed that the movement protein (mp) from tobacco mosaic virus is responsible for altered carbohydrate allocation in tobacco and potato plants. to study whether this is a general feature of viral mps, the movement protein mp17 of potato leafroll virus (plrv), a phloem-restricted luteovirus, was constitutively expressed in tobacco plants. transgenic lines were strongly reduced in height and developed bleached and sometimes even necrotic ... | 1997 | 9418046 |
| transgenic plants expressing potato virus x orf2 protein (p24) are resistant to tobacco mosaic virus and ob tobamoviruses. | the p24 protein, one of the three proteins implicated in local movement of potato virus x (pvx), was expressed in transgenic tobacco plants (nicotiana tabacum xanthi d8 nn). plants with the highest level of p24 accumulation exhibited a stunted and slightly chlorotic phenotype. these transgenic plants facilitate the cell-to-cell movement of a mutant of pvx that contained a frameshift mutation in p24. upon inoculation with tobacco mosaic virus (tmv), the size of necrotic local lesions was signific ... | 1998 | 9420280 |
| evidence that a viral replicase protein is involved in the disassembly of tobacco mosaic virus particles in vivo. | tobacco mosaic virus (tmv) particles have been shown to undergo bidirectional disassembly when they are introduced into host cells. approximately three-quarters of the genomic rna (i.e., the 126-kda and 183-kda protein orfs) is first uncoated in the 5'-to-3' direction and the process is then completed by removal of coat protein molecules in the 3'-to-5' direction. an effort was made to determine whether the 126-kda protein or the 183-kda protein, both of which are involved in replication of the ... | 1997 | 9434732 |
| structure of the stacked disk aggregate of tobacco mosaic virus protein. | the coat protein of tobacco mosaic virus is known to form three different classes of aggregate, depending on environmental conditions, namely helical, disk, and a-protein. among the disk aggregates, there are four-layer, six-layer, and long stacks, which can be obtained by varying the ionic strength and temperature conditions during the association process. the four-layer aggregate has been crystallized, and its structure solved to atomic resolution. the stacked disk aggregate had been presumed ... | 1998 | 9449360 |
| refined atomic model of the four-layer aggregate of the tobacco mosaic virus coat protein at 2.4-a resolution. | previous x-ray studies (2.8-a resolution) on crystals of tobacco mosaic virus coat protein grown from solutions containing high salt have characterized the structure of the protein aggregate as a dimer of a bilayered cylindrical disk formed by 34 chemically identical subunits. we have determined the crystal structure of the disk aggregate at 2.4-a resolution using x-ray diffraction from crystals maintained at cryogenic temperatures. two regions of interest have been extensively refined. first, r ... | 1998 | 9449361 |
| caspar carboxylates: the structural basis of tobamovirus disassembly. | carboxylate groups have been known for many years to drive the disassembly of simple viruses, including tobacco mosaic virus (tmv). the identities of the carboxylate groups involved and the mechanism by which they initiate disassembly have not, however, been clear. structures have been determined at resolutions between 2.9 and 3.5 a for five tobamoviruses by fiber diffraction methods. site-directed mutagenesis has also been used to change numerous carboxylate side chains in tmv to the correspond ... | 1998 | 9449364 |
| phase behavior of mixtures of rods (tobacco mosaic virus) and spheres (polyethylene oxide, bovine serum albumin). | aqueous suspensions of mixtures of the rodlike virus tobacco mosaic virus (tmv) with globular macromolecules such as polyethylene oxide (peo) or bovine serum albumin (bsa) phase separate and exhibit rich and strikingly similar phase behavior. isotropic, nematic, lamellar, and crystalline phases are observed as a function of the concentration of the constituents and ionic strength. the observed phase behavior is considered to arise from attractions between the two particles induced by the presenc ... | 1998 | 9449368 |
| [properties and structure of the tobacco mosaic virus strain k2 genome]. | | 1997 | 9454068 |
| ethylene-insensitive tobacco lacks nonhost resistance against soil-borne fungi. | enhanced ethylene production is an early response of plants to pathogen attack and has been associated with both resistance and susceptibility to disease. tobacco plants were transformed with the mutant etr1-1 gene from arabidopsis, conferring dominant ethylene insensitivity. besides lacking known ethylene responses, these transformants (tetr) did not slow growth when contacting neighboring plants, hardly expressed defense-related basic pathogenesis-related proteins, and developed spontaneous st ... | 1998 | 9465120 |
| cdna cloning, substrate specificity and expression study of tobacco caffeoyl-coa 3-o-methyltransferase, a lignin biosynthetic enzyme. | four caffeoyl-coa 3-o-methyltransferase (ccoaomt) cdna clones were isolated from rna extracted from tmv-infected tobacco leaves using an heterologous dna probe. the cdnas were 84-93% identical in their nucleotide sequences, indicating that they are the products of four closely related genes. a comparison of the ccoaomt cdnas with database sequences and southern blot analysis indicated that they are encoded by a new ccoaomt family of tobacco. overall expression of this gene family in tobacco tiss ... | 1998 | 9484483 |
| light regulation of fed-1 mrna requires an element in the 5' untranslated region and correlates with differential polyribosome association. | light regulation of fed-1 mrna abundance in the leaves of green plants is primarily a post-transcriptional process. previously, we have shown that the fed-1 mrna light response requires an open reading frame, indicating that the light regulation of the mrna depends on its concurrent translation. we now show that light-induced increases in fed-1 mrna abundance are associated with increases in polyribosome association that require both a functional aug and a normal fed-1 translational start contex ... | 1998 | 9501119 |
| refined structure of satellite tobacco mosaic virus at 1.8 a resolution. | the molecular structure of satellite tobacco mosaic virus (stmv) has been refined to 1.8 a resolution using x-ray diffraction data collected from crystals grown in microgravity. the final r value was 0.179 and rfree was 0.184 for 219,086 independent reflections. the final model of the asymmetric unit contained amino acid residues 13 to 159 of a coat protein monomer, 21 nucleotides, a sulfate ion, and 168 water molecules. the nucleotides were visualized as 30 helical segments of nine base-pairs w ... | 1998 | 9514737 |