Assembly-hub function of ER-localized SNARE proteins in biogenesis of tombusvirus replication compartment.

Positive-strand RNA viruses assemble numerous membrane-bound viral replicase complexes within large replication compartments to support their replication in infected cells. Yet the detailed mechanism of how given subcellular compartments are subverted by viruses is incompletely understood. Although, Tomato bushy stunt virus (TBSV) uses peroxisomal membranes for replication, in this paper, we show evidence that the ER-resident SNARE (soluble NSF attachment protein receptor) proteins play critical roles in the formation of active replicase complexes in yeast model host and in plants.

How arbuscular mycorrhizal fungi influence the defense system of sunflower during different abiotic stresses.

The association between terrestrial plants and arbuscular mycorrhizal (AM) fungi is one of the most common and widespread mutualistic plant-fungi interaction. AM fungi are of beneficial effects on the water and nutrient uptake of plants and increase plant defense mechanisms to alleviate different stresses. The aim of this study was to determine the level of polyphenol oxidase (PPO), guaiacol peroxidase (POX) and glutathione S-transferase (GST) enzyme activities and to track the expression of glutathione S-transferase (GST) gene in plant-arbuscular mycorrhizal system under temperature- and mechanical stress conditions.

Viral Replication Protein Inhibits Cellular Cofilin Actin Depolymerization Factor to Regulate the Actin Network and Promote Viral Replicase Assembly.

RNA viruses exploit host cells by co-opting host factors and lipids and escaping host antiviral responses. Previous genome-wide screens with Tomato bushy stunt virus (TBSV) in the model host yeast have identified 18 cellular genes that are part of the actin network. In this paper, we show that the p33 viral replication factor interacts with the cellular cofilin (Cof1p), which is an actin depolymerization factor.

Salicylic Acid Inhibits the Replication of Tomato bushy stunt virus by Directly Targeting a Host Component in the Replication Complex.

Although the plant hormone salicylic acid (SA) plays a central role in signaling resistance to viral infection, the underlying mechanisms are only partially understood. Identification and characterization of SA's direct targets have been shown to be an effective strategy for dissecting the complex SA-mediated defense signaling network. In search of additional SA targets, we previously developed two sensitive approaches that utilize SA analogs in conjunction with either a photoaffinity labeling technique or surface plasmon resonance-based technology to identify and evaluate candidate SA-binding proteins (SABPs) from Arabidopsis.

Co-opted oxysterol-binding ORP and VAP proteins channel sterols to RNA virus replication sites via membrane contact sites.

Viruses recruit cellular membranes and subvert cellular proteins involved in lipid biosynthesis to build viral replicase complexes and replication organelles. Among the lipids, sterols are important components of membranes, affecting the shape and curvature of membranes. In this paper, the tombusvirus replication protein is shown to co-opt cellular Oxysterol-binding protein related proteins (ORPs), whose deletion in yeast model host leads to decreased tombusvirus replication.

Tombusvirus-yeast interactions identify conserved cell-intrinsic viral restriction factors.

To combat viral infections, plants possess innate and adaptive immune pathways, such as RNA silencing, R gene and recessive gene-mediated resistance mechanisms. However, it is likely that additional cell-intrinsic restriction factors (CIRF) are also involved in limiting plant virus replication. This review discusses novel CIRFs with antiviral functions, many of them RNA-binding proteins or affecting the RNA binding activities of viral replication proteins.

Methylation of translation elongation factor 1A by the METTL10-like See1 methyltransferase facilitates tombusvirus replication in yeast and plants.

Replication of tombusviruses and other plus-strand RNA viruses depends on several host factors that are recruited into viral replicase complexes. Previous studies have shown that eukaryotic translation elongation factor 1A (eEF1A) is one of the resident host proteins in the highly purified tombusvirus replicase complex. In this paper, we show that methylation of eEF1A by the METTL10-like See1p methyltransferase is required for tombusvirus and unrelated nodavirus RNA replication in yeast model host.

Tombusvirus replication depends on Sec39p endoplasmic reticulum-associated transport protein.

Positive-stranded RNA viruses subvert subcellular membranes to built viral replicases complexes (VRCs) in infected cells. Tombusviruses use peroxisomal membranes for the assembly of their VRCs and they can efficiently switch to the endoplasmic reticulum membrane in the absence of peroxisomes. In this paper, we show that the ER-resident Sec39p vesicular transport protein is critical for the formation of active VRCs in yeast model host.

The GEF1 proton-chloride exchanger affects tombusvirus replication via regulation of copper metabolism in yeast.

Replication of plus-strand RNA viruses [(+)RNA viruses] is performed by viral replicases, whose function is affected by many cellular factors in infected cells. In this paper, we demonstrate a surprising role for Gef1p proton-chloride exchanger in replication of Tomato bushy stunt virus (TBSV) model (+)RNA virus. A genetic approach revealed that Gef1p, which is the only proton-chloride exchanger in Saccharomyces cerevisiae, is required for TBSV replication in the yeast model host.

Proteome-wide overexpression of host proteins for identification of factors affecting tombusvirus RNA replication: an inhibitory role of protein kinase C.

To identify host genes affecting replication of Tomato bushy stunt virus (TBSV), a small model positive-stranded RNA virus, we overexpressed 5,500 yeast proteins individually in Saccharomyces cerevisiae, which supports TBSV replication. In total, we identified 141 host proteins, and overexpression of 40 of those increased and the remainder decreased the accumulation of a TBSV replicon RNA. Interestingly, 36 yeast proteins were identified previously by various screens, greatly strengthening the relevance of these host proteins in TBSV replication.

Identification of small molecule inhibitors of Tomato bushy stunt virus replication.

The identification of small molecule inhibitors of plant virus RNA replication is useful to develop antiviral drugs and to dissect various steps in the replication process. Moreover, small molecule inhibitors could be effective tools to study similarities in replication strategies of various RNA viruses. By using Tomato bushy stunt virus (TBSV), we tested the effect of various inhibitors of host factors known to facilitate TBSV replication as well as acridine and phenanthridine derivatives, which are known anti-prion compounds, on TBSV replication.

Synergistic roles of eukaryotic translation elongation factors 1Bγ and 1A in stimulation of tombusvirus minus-strand synthesis.

Host factors are recruited into viral replicase complexes to aid replication of plus-strand RNA viruses. In this paper, we show that deletion of eukaryotic translation elongation factor 1Bgamma (eEF1Bγ) reduces Tomato bushy stunt virus (TBSV) replication in yeast host. Also, knock down of eEF1Bγ level in plant host decreases TBSV accumulation.

Making of viral replication organelles by remodeling interior membranes.

Positive-stranded RNA (+RNA) viruses exploit host cell machinery by subverting host proteins and membranes and altering cellular pathways during infection. To achieve robust replication, some +RNA viruses, such as poliovirus (PV), build special intracellular compartments, called viral replication organelles. A recent work from the Altan-Bonnett laboratory [1] gave new insights into the formation of poliovirus replication organelles, which are unique subcellular structures containing many individual replication complexes as a result of dynamic cellular membrane remodeling.

Inhibition of phospholipid biosynthesis decreases the activity of the tombusvirus replicase and alters the subcellular localization of replication proteins.

Replication of plus-strand RNA viruses depends on lipids present in cellular membranes. Recent genome-wide screens have revealed that eight phospholipid biosynthesis genes affected the replication of Tomato bushy stunt virus (TBSV) in yeast model host. To test the importance of phospholipids in TBSV replication, we studied one of the identified genes, namely INO2, which forms a heterodimer with Ino4, and is a transcription activator involved in regulation of phospholipid biosynthesis.

RNA chaperone activity of the tombusviral p33 replication protein facilitates initiation of RNA synthesis by the viral RdRp in vitro.

Small plus-stranded RNA viruses do not code for RNA helicases that would facilitate the proper folding of viral RNAs during replication. Instead, these viruses might use RNA chaperones as shown here for the essential p33 replication protein of Tomato bushy stunt virus (TBSV). In vitro experiments demonstrate that the purified recombinant p33 promotes strand separation of a DNA/RNA duplex.

Inhibition of sterol biosynthesis reduces tombusvirus replication in yeast and plants.

The replication of plus-strand RNA viruses depends on subcellular membranes. Recent genome-wide screens have revealed that the sterol biosynthesis genes ERG25 and ERG4 affected the replication of Tomato bushy stunt virus (TBSV) in a yeast model host. To further our understanding of the role of sterols in TBSV replication, we demonstrate that the downregulation of ERG25 or the inhibition of the activity of Erg25p with an inhibitor (6-amino-2-n-pentylthiobenzothiazole; APB) leads to a 3- to 5-fold reduction in TBSV replication in yeast.

Inhibition of RNA recruitment and replication of an RNA virus by acridine derivatives with known anti-prion activities.

Background: Small molecule inhibitors of RNA virus replication are potent antiviral drugs and useful to dissect selected steps in the replication process. To identify antiviral compounds against Tomato bushy stunt virus (TBSV), a model positive stranded RNA virus, we tested acridine derivatives, such as chlorpromazine (CPZ) and quinacrine (QC), which are active against prion-based diseases.

Methodology/principal Findings: Here, we report that CPZ and QC compounds inhibited TBSV RNA accumulation in plants and in protoplasts.

Expression patterns of cel5A-cel5B, two endoglucanase encoding genes of Thermobifida fusca.

Expression patterns of cel5A and cel5B, two endoglucanase encoding genes of Thermobifida fusca were compared by quantitative real-time PCR. With Avicel as carbon source the transcript level of cel5A continuously increased until the 10th hour of incubation and then a sharp decrease was observed, whereas cel5B presented a slow constitutive expression on this substrate. When the microcrystalline cellulose powder MN300 was used as the inducing carbon source, the expression patterns of the two genes were similar.

The host Pex19p plays a role in peroxisomal localization of tombusvirus replication proteins.

Replication of Tomato bushy stunt virus (TBSV) RNA takes place on the cytosolic membrane surface of peroxisomes in plants and in yeast, a model host. To identify the host proteins involved in assisting the peroxisomal localization of the tombusvirus p33 replication protein, we tested if p33 could bind directly to yeast proteins involved in peroxisomal transport in vitro. This work has led to the demonstration of Pex19p-p33 interaction via pull-down and co-purification experiments.

Development, characterization, and transferability to other Solanaceae of microsatellite markers in pepper (Capsicum annuum L.).

A novel set of informative microsatellite markers for pepper (Capsicum annuum L.) is provided. Screening of approximately 168 000 genomic clones and 23 174 public database entries resulted in a total of 411 microsatellite-containing sequences that could be used for primer design and functional testing.

Crosslinking of glucoamylases via carbohydrates hardly affects catalysis but impairs stability.

Mild oxidation of glucoamylases from Aspergillus niger (E.C.3.