Cloning and expression of antiviral/ribosome-inactivating protein from Bougainvillea xbuttiana

Anti HCV activity and expression inhibition of HCC markers by protein extract from Iberis gibraltarica

Abstract Hepatitis C virus infection (HCV) is the foremost reason of progressive hepatic fibrosis and cirrhosis, with an elevated risk of hepatocellular carcinoma (HCC) development. Medicinal plants have been used for human health benefits for several years, but their therapeutic potential needs to be explored. The main objective of this study was to figure out the in vitro antiviral and anticancer characteristics of total crude protein of Iberis gibraltarica against HCV and HCC. Total crude protein of Iberis gibraltarica was isolated and quantified. The level of cytotoxicity was measured against the HepG2 cell line and it shows no significant cytotoxicity at the concentration of 504µg/ml. The anti-HCV effect was determined by absolute quantification via real time RT-PCR method and viral titer was reduced up to 66% in a dose dependent manner against the total protein of Iberis gibraltarica. The anticancer potential of Iberis gibraltarica was also examined through mRNA expression studies of AFP and GPC3 genes against the total protein of Iberis gibraltarica-treated HepG2 cells. The results show up to 90% of the down-regulation expression of AFP and GPC3. The obtained results indicate the therapeutic potential of total protein of Iberis gibraltarica against HCV and hepatocellular carcinoma in vitro.

Construction of integrative transcriptome to boost systematic exploration of Bougainvillea

Members of the genus Bougainvillea are rich sources of natural dyes, pigments, and traditional medicines. They are also commonly used as ornamentals in roadside landscape construction. However, the horticultural development of Bougainvillea flowers with extended growth periods and coloration is not always feasible. One reason is limited molecular knowledge and no genomic information for Bougainvillea. Here, we compiled an integrative transcriptome of all expressed transcripts for Bougainvillea × buttiana Miss Manila by integrating 20 Illumina-sequencing RNA transcriptomes. The integrative transcriptome consisted of 97,623 distinct transcripts. Of these, 47,006 were protein-coding, 31,109 were non-coding, and 19,508 were unannotated. In addition, we affirmed that the integrative transcriptome could serve as a surrogate reference to the genome in aiding accurate transcriptome assembly. For convenience, we curated the integrative transcriptome database for Bougainvillea, namely InTransBo, which can be freely accessed at http://www.bio-add.org/InTransBo/index.jsp . To the best of our knowledge, the present study is the most comprehensive genomic resource for Bougainvillea up-to-date. The integrative transcriptome helps fill the genomic gap and elucidate the transcriptional nature of Bougainvillea. It may also advance progress in the precise regulation of flowering in horticulture. The same strategy can be readily applied toward the systematic exploration of other plant species lacking complete genomic information.

The role of enzymatic activities of antiviral proteins from plants for action against plant pathogens

Antiviral proteins (AVPs) from plants possess multiple activities, such as N-glycosidase, RNase, DNase enzymatic activity, and induce pathogenesis-related proteins, salicylic acid, superoxide dismutase, peroxidase, and catalase. The N-glycosidase activity releases the adenine residues from sarcin/ricin (S/R) loop of large subunit of ribosomes and interfere the host protein synthesis process and this activity has been attributed for antiviral activity in plant. It has been shown that AVP binds directly to viral genome-linked protein of plant viruses and interfere with protein synthesis of virus. AVPs also possess the RNase and DNase like activity and may be targeting nucleic acid of viruses directly. Recently, the antifungal, antibacterial, and antiinsect properties of AVPs have also been demonstrated. Gene encoding for AVPs has been used for the development of transgenic resistant crops to a broad range of plant pathogens and insect pests. However, the cytotoxicity has been observed in transgenic crops using AVP gene in some cases which can be a limiting factor for its application in agriculture. In this review, we have reviewed various aspects of AVPs particularly their characteristics, possible mode of action and application.

Role of primary metabolites in plant defense against pathogens

Plants under natural environment facing various pathogens, tend to produce defense to maintain their fitness and minimize pathogenic damage. Plant-pathogens interaction is gaining more importance by researches as, their means of the fight are primary metabolites. The ultimate result of either means of defense is pathogenesis or resistance. Plant defense mechanisms can be grouped either into inducible and constitutive defense or chemical, structural and morphological defense. Majority of defense mechanisms have a passive role, i.e. only defensive against pathogens, but a few are very active. Plant primary metabolites are catching interest in their immunity role. Deep information of molecular mechanisms involved during the plant-pathogen system is need of the day for future disease control. This review will highlight the role of primary metabolites and their mechanism of action in plant defense.

The Plant Ribosome-Inactivating Proteins Play Important Roles in Defense against Pathogens and Insect Pest Attacks

Ribosome-inactivating proteins (RIPs) are toxic N-glycosidases that depurinate eukaryotic and prokaryotic rRNAs, thereby arresting protein synthesis during translation. RIPs are widely found in various plant species and within different tissues. It is demonstrated in vitro and in transgenic plants that RIPs have been connected to defense by antifungal, antibacterial, antiviral, and insecticidal activities. However, the mechanism of these effects is still not completely clear. There are a number of reviews of RIPs. However, there are no reviews on the biological functions of RIPs in defense against pathogens and insect pests. Therefore, in this report, we focused on the effect of RIPs from plants in defense against pathogens and insect pest attacks. First, we summarize the three different types of RIPs based on their physical properties. RIPs are generally distributed in plants. Then, we discuss the distribution of RIPs that are found in various plant species and in fungi, bacteria, algae, and animals. Various RIPs have shown unique bioactive properties including antibacterial, antifungal, antiviral, and insecticidal activity. Finally, we divided the discussion into the biological roles of RIPs in defense against bacteria, fungi, viruses, and insects. This review is focused on the role of plant RIPs in defense against bacteria, fungi, viruses, and insect attacks. The role of plant RIPs in defense against pathogens and insects is being comprehended currently. Future study utilizing transgenic technology approaches to study the mechanisms of RIPs will undoubtedly generate a better comprehending of the role of plant RIPs in defense against pathogens and insects. Discovering additional crosstalk mechanisms between RIPs and phytohormones or reactive oxygen species (ROS) against pathogen and insect infections will be a significant subject in the field of biotic stress study. These studies are helpful in revealing significance of genetic control that can be beneficial to engineer crops tolerance to biotic stress.

Phyto-metabolites; An Impregnable Shield against Plant Viruses

Worldwide, economically important crops are under continuous threat from plant viruses as they reproduce within the host and spread via various biological and non biological means. The problem can be minimized via application of integrated management approaches involving utilization of resistant genotypes and reducing the insect vector population. But such strategies are rarely applied in developing countries and farmers prefer to use chemicals against all type of diseases. But increasing use of pesticides is a leading cause of disaster to our ecosystem so alternative means such as phyto-metabolites should be explored for eco friendly management of plant viruses. So here we have reviewed about different phyto-metabolites that can be effectively and potentially used against various plant virus diseases. We further explained about the various primary and secondary metabolites such as alkaloids, essential oils, flavonoids, polysaccharides and proteins. The review highlights the recent advances in the field of phyto-metabolites utilization against plant viruses and sums up via hoping through prospects that future drugs will be safer for human beings and our ecosystem.

Advances and prospects in biogenic substances against plant virus: A review

Plant virus diseases, known as 'plant cancer', are the second largest plant diseases after plant fungal diseases, which have caused great damage to agricultural industry. Since now, the most direct and effective method for controlling viruses is chemotherapeutics, except for screening of anti-disease species. As the occurrence and harm of plant diseases intensify, production and consumption of pesticides have increased year by year, and greatly contributed to the fertility of agriculture, but also brought a series of problems, such as the increase of drug resistance of plant pathogens and the excessive pesticide residues. In recent years, biopesticide, as characterized by environmentally safe due to low residual, safe to non-target organism due to better specificity and not as susceptible to produce drug resistance due to diverse work ways, has gained more attention than ever before and exhibited great development potential. Now much progress has been made about researches on new biogenic anti-plant-virus substances. The types of active components include proteins, polysaccharides and small molecules (alkaloids, flavonoids, phenols, essential oils) from plants, proteins and polysaccharides from microorganisms, polysaccharides from algae and oligochitosan from animals. This study summarized the research advance of biogenic anti-plant-virus substances in recent years and put forward their further development in the future.

Ribosome-inactivating and related proteins

Ribosome-inactivating proteins (RIPs) are toxins that act as N-glycosidases (EC 3.2.2.22). They are mainly produced by plants and classified as type 1 RIPs and type 2 RIPs. There are also RIPs and RIP related proteins that cannot be grouped into the classical type 1 and type 2 RIPs because of their different sizes, structures or functions. In addition, there is still not a uniform nomenclature or classification existing for RIPs. In this review, we give the current status of all known plant RIPs and we make a suggestion about how to unify those RIPs and RIP related proteins that cannot be classified as type 1 or type 2 RIPs.

BDP-30, a systemic resistance inducer from Boerhaavia diffusa L., suppresses TMV infection, and displays homology with ribosome-inactivating proteins

Root extract of Boerhaavia diffusa L. induced systemic resistance in tobacco against Tobacco mosaic virus. A 30 kDa protein was isolated as the active component, called BDP-30 on the basis of the molecular weight and source plant. BDP-30, a glycoprotein, was found to be temperature and protease resistant. It was basic, possessing a pI greater than 9.0. In-gel proteolytic digestion of BDP-30 generated two peptides that possessed the amino acid sequence KLYDIPPLR and KVTLPYSGNYER by LC/MS/MS. Both peptides shared absolute sequence identity with trichosanthin, a ribosome-inactivating protein from Trichosanthes kirilowii, and a 78 percent and 100 percent homology respectively with an RIP from Bryonia dioica, bryodin. Further, effort was made to look at the fate of TMV in induced resistant Nicotiana tabacum cv. Xanthi, a systemic host of the virus, at specified days after inoculation in control and treated plants. TMV coat protein (CP) was detected by immunoblot 7 days post inoculation up to 21 days in the control set, but not in treated resistant plants. TMV RNA was detected by RT-PCR using TMV-CP specific primers. Resistant tobacco did not show presence of TMV RNA up to 21 days of inoculation. This suggests that BDP-30 may be suppressing TMV replication.

Alpha-momorcharin, a RIP produced by bitter melon, enhances defense response in tobacco plants against diverse plant viruses and shows antifungal activity in vitro

Alpha-momorcharin (α-MMC) is type-1 ribosome inactivating proteins (RIPs) with molecular weight of 29 kDa and has lots of biological activity. Our recent study indicated that the α-MMC purified from seeds of Momordica charantia exhibited distinct antiviral and antifungal activity. Tobacco plants pre-treated with 0.5 mg/mL α-MMC 3 days before inoculation with various viruses showed less-severe symptom and less reactive oxygen species (ROS) accumulation compared to that inoculated with viruses only. Quantitative real-time PCR analysis revealed that the replication levels of viruses were lower in the plants treated with the α-MMC than control plants at 15 days post inoculation. Moreover, the coat protein expression of viruses was almost completely inhibited in plants which were treated with the α-MMC compared with control plants. Furthermore, the SA-responsive defense-related genes including non-expressor of pathogenesis-related genes 1 (NPR1), PR1, PR2 were up-regulated and activities of some antioxidant enzymes including superoxide dismutase (SOD), catalase (CAT), peroxidase (POD) were increased after the α-MMC treatment. In addition, the α-MMC (500 μg/mL) revealed remarkable antifungal effect against phytopathogenic fungi, in the growth inhibition range 50.35-67.21 %, along with their MIC values ranging from 100 to 500 μg/mL. The α-MMC had also a strong detrimental effect on spore germination of all the tested plant pathogens along with concentration as well as time-dependent kinetic inhibition of Sclerotinia sclerotiorum. The α-MMC showed a remarkable antiviral and antifungal effect and hence could possibly be exploited in crop protection for controlling certain important plant diseases.

Cloning and soluble expression of mature alpha-luffin from Luffa cylindrica and its antitumor activities in vitro

Luffin-a, a single-chain Type I ribosome-inactivating protein, which is known to be the most toxic of the luffin family and apparently possesses antitumor activity, was isolated from Luffa cylindrica seeds. In the present study, mature alpha-luffin was cloned from L. cylindrica and it was found that mature alpha-luffin shared 96% amino acid similarity with luffin-a. The recombinant mature alpha-luffin was successfully expressed in a partly soluble form in Escherichia coli after optimization of expression conditions. The effects of the recombinant protein on bacterial growth and its in vitro protein synthesis inhibition activity were tested. Then, its antitumor activities against different human cancer cell lines were evaluated by CCK-8 assay and flow cytometry. The results indicated that the recombinant alpha-luffin was slightly toxic to E. coli. It could inhibit protein synthesis in the rabbit reticulocyte lysate system. At the same time, it inhibited the growth of the tumor cell lines in a dose- and time-dependent manner. Additionally, recombinant alpha-luffin was able to induce cell death by apoptosis. The cytotoxicity of alpha-luffin towards tumor cells makes it a potential antitumor agent.