Purification and Characterization of a Secretory Alkaline Metalloprotease with Highly Potent Antiviral Activity from Serratia marcescens Strain S3

Rhizosphere: Role of bacteria to manage plant diseases and sustainable agriculture-A review

General plant diseases as well as soil-borne pathogens severely reduce agricultural yield. The rhizosphere (the region of the soil that includes and surrounds the roots) is an important niche for microbial diversity in particular phytobeneficial bacteria including plant growth-promoting rhizobacteria (PGPR) which have been used for a very long time to combat plant diseases. Pathogen control and crop productivity can both be improved through the use of PGPR several mechanisms, including iron-based nutrition, antibiotics, volatile substances, enzymes, biofilm, allelochemicals, and so on. Their modes of action and molecular mechanisms have improved our comprehension of how they are used to control crop disease. Therefore, there is a lot of literal information available regarding PGPR, but this review stands out since it starts with the fundamentals: the concept of the rhizosphere and the colonization process of the latter, particularly because it covers the most mechanisms. A broad figure is used to present the study's findings. The advantages of using PGPR as bioinoculants in sustainable agriculture are also mentioned.

Cross-Talk of Protein Expression and Lysine Acetylation in Response to TMV Infection in Nicotiana benthamiana

Lysine acetylation (K^ac), a reversible PTM, plays an essential role in various biological processes, including those involving metabolic pathways, pathogen resistance, and transcription, in both prokaryotes and eukaryotes. TMV, the major factor that causes the poor quality of Solanaceae crops worldwide, directly alters many metabolic processes in tobacco. However, the extent and function of K^ac during TMV infection have not been determined. The validation test to detect K^ac level and viral expression after TMV infection and Nicotinamide (NAM) treatment clarified that acetylation was involved in TMV infection. Furthermore, we comprehensively analyzed the changes in the proteome and acetylome of TMV-infected tobacco (Nicotiana benthamiana) seedlings via LC-MS/MS in conjunction with highly sensitive immune-affinity purification. In total, 2082 lysine-acetylated sites on 1319 proteins differentially expressed in response to TMV infection were identified. Extensive bioinformatic studies disclosed changes in acetylation of proteins engaged in cellular metabolism and biological processes. The vital influence of K^ac in fatty acid degradation and alpha-linolenic acid metabolism was also revealed in TMV-infected seedlings. This study first revealed K^ac information in N. benthamiana under TMV infection and expanded upon the existing landscape of acetylation in pathogen infection.

Microscale thermophoresis as a powerful growing analytical technique for the investigation of biomolecular interaction and the determination of binding parameters

The in vitro panel of technologies to address biomolecular interactions are in play, however microscale thermophoresis is continuously increasing in use to represent a key player in this arena. This review highlights the usefulness of microscale thermophoresis in the determination of molecular and biomolecular affinity interactions. This work reviews the literature from January 2016 to January 2022 about microscale thermophoresis. It gives a summarized overview about both the state-of the art and the development in the field of microscale thermophoresis. The principle of microscale thermophoresis is also described supported with self-created illustrations. Moreover, some recent advances are mentioned that showing application of the technique in investigating biomolecular interactions in different fields. Finally, advantages as well as drawbacks of the technique in comparison with other competing techniques are summarized.

Serratia marcescens-S3 inhibits Potato virus Y by activating ubiquitination of molecular chaperone proteins NbHsc70-2 in Nicotiana benthamiana

The potato virus Y (PVY) is a plant virus that causes massive crop losses globally, especially in Solanaceae crops. A strain of the plant growth-promoting rhizobacterium (PGPR), Serratia marcescens-S3 was found to inhibit PVY replication in Nicotiana benthamiana. However, there have been no in-depth studies demonstrating the underlying mechanism. In the current study, we found that ubiquitination of NbHsc70-2 is an important way for Serratia marcescens-S3 to trigger induced systemic resistance (ISR). After the treatment with S. marcescens-S3, the protein level of NbHsc70-2 reduced significantly. Inhibiting of ubiquitination increased the accumulation of NbHsc70-2 in plants and reduced S. marcescens-S3-mediated resistance to PVY. Furthermore, transgenic engineered Nicotiana benthamiana NbHsc70-2KO and NbHsc70-2USM were constructed using CRISPR-Cas9-mediated NbHsc70-2 knock-out and ubiquitination respectively. S. marcescens-S3 significantly reduced the inhibition of NbHsc70-2 protein accumulation in NbHsc70-2KO and NbHsc70-2USM . The virulence of PVY was stronger in NbHsc70-2USM than the wild-type plants. These results showed that S. marcescens-S3 increases the ubiquitination of NbHsc70-2 to inhibit the recruitment of molecular chaperone NbHsc70-2 to reduce its replication and infection of PVY.

HACC-Based Nanoscale Delivery of the NbMLP28 Plasmid as a Crop Protection Strategy for Viral Diseases

Resistant genes as an effective strategy to antivirus of plants are at the core of sustainability efforts. We use the antiviral protein major latex protein 28 (NbMLP28 plasmid) and N-2-hydroxypropyl trimethyl ammonium chloride chitosan (HACC) designated as the HACC/NbMLP28 complex as protective gene delivery vectors to prepare nanonucleic acid drugs. The maximum drug loading capacity of HACC was 4. The particle size of HACC/NbMLP28 was measured by transmission electron microscopy and found to be approximately 40-120 nm, the particle dispersion index (PDI) was 0.448, and the ζ-potential was 22.3 mV. This facilitates its ability to deliver particles. Different controls of laser scanning confocal experiments verified the effective expression of NbMLP28 and the feasibility of nanodelivery. The optimal ratio of HACC/plasmid was 2:1. Finally, the nanoparticle/plasmid complex was tested for its ability to control diseases and was found to significantly improve resistance to three viruses. The enhanced resistance was particularly notable 4 days after inoculation. Taken together, these results indicate that HACC/NbMLP28 is a promising tool to treat plant viruses. To the best of our knowledge, this is the first study that successfully delivered and expressed antiviral protein particles in plants. This gene delivery system can effectively load antiviral plasmids and express them in plant leaves, significantly affecting the plant resistance of three RNA viruses.

BLB8, an antiviral protein from Brevibacillus laterosporus strain B8, inhibits Tobacco mosaic virus infection by triggering immune response in tobacco

BACKGROUND

Tobacco mosaic virus (TMV) is one of destructive plant viruses, causing serious economic losses in the world. Using antiviral proteins or elicitors to inhibit viral infection or promote plant immunity is one of the efficient strategies against TMV. Our previous study identified that the fermentation broth of Brevibacillus laterosporus strain B8 showed strong antiviral activity against TMV. However, the active antiviral ingredient is still unclear.

RESULTS

Here, BLB8 (B. laterosporus strain B8 protein, BLB8), an antiviral protein from B. laterosporus strain B8 was isolated and characterized. BLB8 showed protective, inactive and curative effects against TMV, and the inhibition rate reached up to 63%, 83% and 55%, respectively. BLB8 infiltrated around the infection site of the recombinant virus TMV-GFP inhibited the systemic extend and movement of TMV. Pretreatment of the bottom leaves with BLB8 inhibited the spread and accumulation of TMV in upper systemic leaves. Furthermore, BLB8 caused hypersensitive response (HR) in a dose-dependent way, promoted H2 O2 accumulation, and induced the expression of defense-relative genes in Nicotiana benthamiana.

CONCLUSION

The antiviral protein BLB8 from B. laterosporus strain B8 effectively inhibits TMV infection in inactivation, protective and curative effects through triggering plant immunity in tobacco. Therefore, the present study provides a new antiviral agent for prevention and control of viral disease. © 2021 Society of Chemical Industry.

Virus-Based Supramolecular Structure and Materials: Concept and Prospects

Rodlike and spherelike viruses are various monodisperse nanoparticles that can display small molecules or polymers with unique distribution following chemical modifications. Because of the monodisperse property, aggregates in synthetic protein-polymer nanoparticles could be eliminated, thus improving the probability for application in protein-polymer drug. In addition, the monodisperse virus could direct the growth of metal materials or inorganic materials, finding applications in hydrogel, drug delivery, and optoelectronic and catalysis materials. Benefiting from the advantages, the virus or viruslike particles have been widely explored in the field of supramolecular chemistry. In this review, we describe the modification and application of virus and viruslike particles in surpramolecular structures and biomedical research.

The Role of Bacterial Proteases in Microbe and Host-microbe Interactions

BACKGROUND

Secreted proteases are an important class of factors used by bacterial to modulate their extracellular environment through the cleavage of peptides and proteins. These proteases can range from broad, general proteolytic activity to high degrees of substrate specificity. They are often involved in interactions between bacteria and other species, even across kingdoms, allowing bacteria to survive and compete within their niche. As a result, many bacterial proteases are of clinical importance. The immune system is a common target for these enzymes, and bacteria have evolved ways to use these proteases to alter immune responses for their benefit. In addition to the wide variety of human proteins that can be targeted by bacterial proteases, bacteria also use these secreted factors to disrupt competing microbes, ranging from outright antimicrobial activity to disrupting processes like biofilm formation.

OBJECTIVE

In this review, we address how bacterial proteases modulate host mechanisms of protection from infection and injury, including immune factors and cell barriers. We also discuss the contributions of bacterial proteases to microbe-microbe interactions, including antimicrobial and anti-biofilm dynamics.

CONCLUSION

Bacterial secreted proteases represent an incredibly diverse group of factors that bacteria use to shape and thrive in their microenvironment. Due to the range of activities and targets of these proteases, some have been noted for having potential as therapeutics. The vast array of bacterial proteases and their targets remains an expanding field of research, and this field has many important implications for human health.

In Vitro and In Vivo Antibacterial Activity of Serratamid, a Novel Peptide-Polyketide Antibiotic Isolated from Serratia plymuthica C1, against Phytopathogenic Bacteria

A new hybrid non-ribosomal peptide-polyketide antibiotic (serratamid) for phytoprotection was isolated from the ethyl acetate layer of tryptic soy agar culture of the soil bacterium Serratia plymuthica C1 through bioassay-guided fractionation. Its chemical structure was elucidated using instrumental analyses, such as mass and nuclear magnetic resonance spectrometry. Serratamid showed antibacterial activity against 15 phytopathogenic bacteria, with minimum inhibitory concentration (MIC) values ranging from 0.244 to 31.25 μg/mL. In vitro, it displayed strong antibacterial activity against Ralstonia solanacearum and four Xanthomonas spp., with MIC values (0.244-0.488 μg/mL) superior to those of streptomycin sulfate, oxolinic acid, and oxytetracycline. Further, serratamid and the ethyl acetate layer of S. plymuthica C1 effectively reduced bacterial wilt caused by R. solanacearum on tomato seedlings and fire blight caused by Erwinia on apple fruits in a dose-dependent manner. These results suggest that serratamid is a promising candidate as a potent bactericide for controlling bacterial diseases.

Comprehensive Proteomic Analysis of Lysine Ubiquitination in Seedling Leaves of Nicotiana tabacum

Lysine ubiquitination, a widely studied posttranslational modification, plays vital roles in various biological processes in eukaryotic cells. Although several studies have examined the plant ubiquitylome, no such research has been performed in tobacco, a model plant for molecular biology. Here, we comprehensively analyzed lysine ubiquitination in tobacco (Nicotiana tabacum) using LC-MS/MS along with highly sensitive immune-affinity purification. In total, 964 lysine-ubiquitinated (K^ub) sites were identified in 572 proteins. Extensive bioinformatics studies revealed the distribution of these proteins in various cellular locations, including the cytoplasm, chloroplast, nucleus, and plasma membrane. Notably, 25% of the K^ub proteins were located in the chloroplast of which 21 were enzymatically involved in important pathways, that is, photosynthesis and carbon fixation. Western blot analysis indicated that TMV infection can cause changes in ubiquitination levels. This is the first comprehensive proteomic analysis of lysine ubiquitination in tobacco, illustrating the vital role of ubiquitination in various physiological and biochemical processes and representing a valuable addition to the existing landscape of lysine ubiquitination.

Design, Synthesis, and Anti-ToCV Activity of Novel Pyrimidine Derivatives Bearing a Dithioacetal Moiety that Targets ToCV Coat Protein

Novel pyrimidine sulfide derivatives containing a dithioacetal and strobilurin moiety were designed and synthesized. Their antiviral activities against tomato chlorosis virus (ToCV) were investigated through the tomato chlorosis virus coat protein (ToCVCP)-oriented screening method. Microscale thermophoresis was used to study the interaction between the compound and the ToCVCP. Compounds B13 and B23 interacted better with ToCVCP than the other compounds and had dissociation constant (Kd) values of 0.09 and 0.06 μM, respectively. These values were lower than those of the control agents, ningnanmycin (0.19 μM) and ribavirin (6.54 μM), which indicated that the compounds had a strong binding effect with ToCVCP. Quantitative real-time polymerase chain reaction was used to evaluate the role of compounds B13 and B23 in the gene regulation of ToCVCP. Both compounds significantly reduced the expression level of the ToCVCP gene in Nicotiana benthamiana with reduction values of 88 and 83%, which were better than those of ningnanmycin (65%) and lead compound C14 (73%). Pyrimidine sulfide containing a dithioacetal and strobilurin moiety is significant in the research and development of novel anti-ToCV agents.

Design, synthesis, anti-TMV activity, and preliminary mechanism of cinnamic acid derivatives containing dithioacetal moiety

A series of cinnamic acid derivatives, which contained dithioacetal moiety, were designed and synthesized, and their anti-plant virus activity against Tobacco mosaic virus (TMV) were evaluated. Most target compounds exhibited good anti-plant virus activities. Compound 2y, especially at 500 mg/L concentration, had an excellent activity against TMV, and its curative, protective, and inactivating activities were 62.5%, 61.8%, and 83.5%, respectively. These activity values were significantly superior to those of ribavirin (45.9%, 39.8%, and 70.3%) and xiangcaoliusuobingmi (44.7%, 48.3%, and 71.7%) and comparable to those of ningnanmycin (61.9%, 53.3%, and 85.2%). Compound 2y presented an EC₅₀ value of 50.7 mg/L for inactivating activity against TMV, which was superior to those of ningnanmycin (51.5 mg/L), ribavirin (160.4 mg/L), and xiangcaoliusuobingmi (83.0 mg/L). Through transmission electron microscopy, we found that compound 2y caused a certain degree of damage to TMV particles, which caused them to break and bend. Four conventional hydrogen bonds were formed with amino acid residues GLN34, THR37, ARG90, and ARG46 of TMV coat protein (CP) through molecular docking. Microscale thermophoresis test results showed that compound 2y with TMV CP had a strong binding force, and the dissociation constant (K_d) was 1.6 μM. In summary, the cinnamic acid derivatives containing dithioacetal moiety provide a foundation for further research on antiviral agents.

Design, Synthesis, and Antiviral Activities of Coumarin Derivatives Containing Dithioacetal Structures

In this study, a series of coumarin derivatives containing dithioacetals were synthesized, characterized, and assessed for their anti-tobacco mosaic virus (TMV) activities. Biological tests showed that most of the title compounds exhibited significant anti-TMV biological activities; in particular, compound b21 showed good inactivating activity anti-TMV, with an EC₅₀ of 54.2 mg/L, superior to that of ribavirin (134.2 mg/L). Transmission electron microscopy analyses showed that compound 21 severely ruptured TMV particles. The interaction of compound b21 with TMV coat protein (TMV CP) was investigated using microscale thermophoresis and molecular docking. Compound b21 exhibited a strong binding ability to TMV CP, with a value of 2.9 μM, superior to ribavirin.