The ubiquitin system in plants

Kampen, Jan von; Wettern, Michael; Schulz, Margot

doi:10.1034/j.1399-3054.1996.970326.x

Cited by 25 publications

(13 citation statements)

References 28 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Furthermore, MP-GFP fusions accumulated preferentially on the cisternal ER (Reichel and Beachy, 2000). Protein degradation by the 26S proteasome is a ubiquitin-dependent pathway in which polyubiquitinated proteins become targeted selectively for degradation (Vierstra, 1996;Von Kampen et al, 1996). We found that the MP R3 phenotype could be reproduced when viral infection sites expressing MP WT were treated with a specific proteasome inhibitor, indicating that the MP R3 phenotype might arise from impairment of the ubiquitin-proteasome degradation pathway.…”

Section: Mp Degradationmentioning

confidence: 65%

Functional Analysis of a DNA-Shuffled Movement Protein Reveals That Microtubules Are Dispensable for the Cell-to-Cell Movement of Tobacco mosaic virus

Gillespie¹,

Boevink²,

Haupt³

et al. 2002

Plant Cell

161

171

View full text Add to dashboard Cite

show abstract

Section: Mp Degradationmentioning

confidence: 65%

Functional Analysis of a DNA-Shuffled Movement Protein Reveals That Microtubules Are Dispensable for the Cell-to-Cell Movement of Tobacco mosaic virus

Gillespie¹,

Boevink²,

Haupt³

et al. 2002

Plant Cell

161

171

View full text Add to dashboard Cite

show abstract

“…Interestingly, ubiquitin was implicated in plant-pathogen interactions (49), and ubiquitination of some viral coat proteins has been demonstrated (12,17). A very small proportion of the TMV CP was found to be monoubiquitinated (approximately one event per virion), although a function of this modification has not been determined (12).…”

Section: Discussionmentioning

confidence: 99%

“…In recent years many components of the 26S proteasome degradation pathway have been identified in plants and shown to have remarkable homology to yeast and mammalian systems (48,49). Interestingly, ubiquitin was implicated in plant-pathogen interactions (49), and ubiquitination of some viral coat proteins has been demonstrated (12,17).…”

Section: Discussionmentioning

confidence: 99%

Degradation of Tobacco Mosaic Virus Movement Protein by the 26S Proteasome

Reichel

Beachy

2000

J Virol

144

110

View full text Add to dashboard Cite

Cell-to-cell spread of tobacco mosaic virus is facilitated by the virus-encoded 30-kDa movement protein (MP). This process involves interaction of viral proteins with host components, including the cytoskeleton and the endoplasmic reticulum (ER).During virus infection, high-molecular-weight forms of MP were detected in tobacco BY-2 protoplasts. Inhibition of the 26S proteasome by MG115 and clasto-lactacystin-␤-lactone enhanced the accumulation of high-molecular-weight forms of MP and led to increased stability of the MP. Such treatment also increased the apparent accumulation of polyubiquitinated host proteins. By fusion of MP with the jellyfish green fluorescent protein (GFP), we demonstrated that inhibition of the 26S proteasome led to accumulation of the MP-GFP fusion preferentially on the ER, particularly the perinuclear ER. We suggest that polyubiquitination of MP and subsequent degradation by the 26S proteasome may play a substantial role in regulation of virus spread by reducing the damage caused by the MP on the structure of cortical ER.To spread infection from cell to cell, plant viruses must cross the rigid cell wall between cells by exploiting cytoplasmic bridges referred to as plasmodesmata. These cytoplasmic channels maintain continuity of the plasma membrane, the cytoplasm, and the endoplasmic reticulum (ER) between neighboring cells (30,33,43). Plasmodesmata enable neighboring plant cells to exchange small signal molecules and metabolites but under normal conditions exclude molecules of more than 1 kDa. Thus, plasmodesmata must be modified in order to allow the spread of infection from cell to cell. During replication, plant viruses produce proteins that facilitate cell-cell transport, referred to as movement proteins (MP). MPs have been demonstrated to directly or indirectly modify the size exclusion limit of plasmodesmata to permit viral spread (10,30,56).Tobacco mosaic tobamovirus (TMV), a plus-sense RNA virus, encodes four proteins. The 126-kDa replicase and a 183-kDa replicase readthrough product are involved in genome amplification and are translated from genomic RNA, while the 17.5-kDa coat protein (CP) and the 30-kDa MP are translated from subgenomic RNAs.Although there have been very detailed investigations of the function of the TMV MP and its intracellular localization, few studies have dealt with the regulation of virus spread and the involvement of the MP in this process. Genetic studies involving transgenic plants expressing functional and nonfunctional MP variants, and studies involving viruses that contain mutations in the MP, established the role of the MP in facilitating cell-cell spread of infection (5,9,10,14,20,32). Electron microscopy, fluorescence microscopy, and cell fractionation were used to elucidate the intracellular localization of MP and MP-GFP fusion proteins (1,18,19,31,38,45,46). These studies established that the MP is tightly associated with plasmodesmata in transgenic plants and that during virus infection there is a transient association with several compartmen...

show abstract

“…Another candidate (housekeeping gene) for being suppressed is the ubiquitin genes, the products of which function in a protein degradation system (von Kampen et al, 1996). Suppressed expression of a ubiquitin gene, which may cause a disturbance of cellular homeostasis, has been reported to be involved in the TMV-induced HR in tobacco (Becker et al, 1993;Karrer et al, 1998).…”

Section: Discussionmentioning

confidence: 99%

Reduced Levels of Chloroplast FtsH Protein in Tobacco Mosaic Virus–Infected Tobacco Leaves Accelerate the Hypersensitive Reaction

et al. 2000

View full text Add to dashboard Cite

In tobacco cultivars resistant to tobacco mosaic virus (TMV), infection results in the death of the infected cells accompanying the formation of necrotic lesions. To identify the genes involved in this hypersensitive reaction, we isolated the cDNA of tobacco DS9, the transcript of which decreases before the appearance of necrotic lesions. The DS9 gene encodes a chloroplastic homolog of bacterial FtsH protein, which serves to maintain quality control of some cytoplasmic and membrane proteins. A large quantity of DS9 protein was found in healthy leaves, whereas the quantity of DS9 protein in infected leaves decreased before the lesions appeared. In transgenic tobacco plants containing less and more DS9 protein than wild-type plants, the necrotic lesions induced by TMV were smaller and larger, respectively, than those on wild-type plants. These results suggest that a decrease in the level of DS9 protein in TMV-infected cells, resulting in a subsequent loss of function of the chloroplasts, accelerates the hypersensitive reaction. INTRODUCTIONThe hypersensitive reaction (HR) is a plant defense system against pathogen attack. HR is defined as the rapid death of infected cells accompanying formation of necrotic lesions in which pathogens are thought to be enclosed (Goodman and Novacky, 1994). The HR of tobacco to tobacco mosaic virus (TMV) occurs in cultivars carrying the resistance gene N ( NN tobacco) but not in cultivars lacking the N gene ( nn tobacco) (Holmes, 1938; Whitham et al., 1994). Induction of the N gene-mediated HR requires the temperature to be below 22 to 26 Њ C (Kassanis, 1952;Shimomura, 1971; Weststeijn, 1981), suggesting that the gene can function at temperatures below this range.We previously observed that when TMV-inoculated leaves were treated with heat shock or actinomycin D, necrotic lesions were induced in not only NN but also in nn tobacco, even at 30 Њ C, a nonpermissive temperature for the N gene (Shimomura and Ohashi, 1971;Ohashi and Shimomura, 1972). In the actinomycin D-treated leaves in which necrotic lesions were induced, the synthesis of nucleic acid in the host plant was greatly suppressed, whereas the synthesis of TMV RNA was suppressed only slightly (Shimomura and Ohashi, 1980). In contrast to treatment with actinomycin D, treatment with other chemicals, including rifampicin, 2-thiouracil, and cycloheximide, which suppress RNA or protein synthesis in both the TMV and the host plant, did not induce necrotic lesions to form (Ohashi and Shimomura, 1972). Given that actinomycin D forms intercalation complexes with DNA, thereby blocking transcription (Waring, 1981), and that heat shock suppresses transcription of housekeeping genes (Lindquist, 1986;Nover et al., 1989), we hypothesized that suppressing the transcription of certain housekeeping genes in NN tobacco plants after infection with TMV could induce the HR.To isolate such candidate genes, we used a synchronous HR-inducing system based on a temperature shift. Incubation at 30 Њ C of TMV-infected NN tobacco leaves results in 1 Curr...

show abstract

The ubiquitin system in plants

Cited by 25 publications

References 28 publications

Functional Analysis of a DNA-Shuffled Movement Protein Reveals That Microtubules Are Dispensable for the Cell-to-Cell Movement of Tobacco mosaic virus

Functional Analysis of a DNA-Shuffled Movement Protein Reveals That Microtubules Are Dispensable for the Cell-to-Cell Movement of Tobacco mosaic virus

Degradation of Tobacco Mosaic Virus Movement Protein by the 26S Proteasome

Reduced Levels of Chloroplast FtsH Protein in Tobacco Mosaic Virus–Infected Tobacco Leaves Accelerate the Hypersensitive Reaction

Contact Info

Product

Resources

About