Amandeep Kaur Walia

Microbial lectins and their prospective mitogenic potential

Abstract The binding of mitogenic lectins to the glycoconjugates on cell surface receptor triggers multitude of reactions involving different signal transduction pathways which ultimately results in cell proliferation. Since 1960 after the chance discovery of mitogenic property of lectins by Nowell, it has attracted more attention. The property of stimulation of mature lymphocytes aided the immunological investigations to study and analyse the mechanism of cell stimulation and division. Plant lectins are extensively studied for mitogenic activity and their widespread applications are also reported. During the past two decades, the study of biological properties of microbial lectins has increased tremendously. Their biological activities including mitogenic potential are equally applicable as that of plant lectins. The review mainly focuses on mitogenic potential of microbial lectins. It will provide a comprehensive view regarding distribution of this remarkable property among microbes including algae, fungi and bacteria, mechanisms and models of mitogenic stimulation, and also assays being employed to detect the mitogenic activity.

Characteristics of lichen lectins and their role in symbiosis

Lectins are proteins or glycoproteins of non-immune origin which bind reversibly to carbohydrates that are exposed on cellular surfaces and mediate cellular recognition processes in a variety of biological interactions. Though initially discovered in plants, lectins from various sources including lichens, have been extensively studied by researchers all over the world. The symbiotic interaction between a fungus (mycobiont) and its photosynthetic partner (photobiont), usually an alga, constitutes a lichen. Some lichen lectins displays activity to human or animal erythrocytes. Although only a few lichen lectins have been examined to date, their characteristics suggest that they play an important role in the symbiotic interactions of this association. Lectin binding and the related enzymatic activity with respect to algal cell recognition illustrates a finely tuned mechanistic system which involved in the lichen symbiosis. This review provides an overview of the characteristics of lichen lectins and an insight into lectin-mediated symbiotic interactions and the galectin encoding genes. Future prospects for lichen lectin research in different areas are also highlighted.

Amoebiasis vaccine development: A snapshot on E. histolytica with emphasis on perspectives of Gal/GalNAc lectin

Amoebiasis/amebiasis is a gastrointestinal infection caused by an enteric dwelling protozoan, Entamoeba histolytica. The disease is endemic in the developing world and is transmitted mainly via the faecal-oral route (e.g., in water or food) and may or may not be symptomatic. This disease of socio-economic importance worldwide involves parasite adherence and cytolysis of human cells followed by invasion that is mediated by galactose-binding (Gal/GalNAc) surface lectin. Disruption of the mucus layer leads to invasive intestinal and extraintestinal infection. Gal-lectin based vaccinations have conferred protection in various animal models against E. histolytica infections. Keeping in view the pivotal role of Gal/GalNAc lectin in amoebiasis vaccine development, its regulation, genomic view of the parasite involving gene conversion in lectin gene families, current knowledge about involvement of Gal/GalNAc lectin in adherence, pathogenicity, signalling, encystment, generating host immune response, and in turn protozoa escape strategies, and finally its role as effective vaccine candidate has been described. This review will help researchers to explore pathogenesis mechanism along with genomic studies and will also provide a framework for future amoebiasis vaccine development studies.

Protozoa lectins and their role in host–pathogen interactions

Lectins are proteins/glycoproteins of non-immune origin that agglutinate red blood cells, lymphocytes, fibroblasts, etc., and bind reversibly to carbohydrates present on the apposing cells. They have at least two carbohydrate binding sites and their binding can be inhibited by one or more carbohydrates. Owing to carbohydrate binding specificity of lectins, they mediate cell-cell interactions and play role in protozoan adhesion and host cell cytotoxicity, thus are central to the pathogenic property of the parasite. Several parasitic protozoa possess lectins which mediate parasite adherence to host cells based on their carbohydrate specificities. These interactions could be exploited for development of novel therapeutics, targeting the adherence and thus helpful in eradicating wide spread of protozoan diseases. The current review highlights the present state knowledge with regard to protozoal lectins with an emphasis on their haemagglutination activity, carbohydrate specificity, characteristics and also their role in pathogenesis notably as adhesion molecules, thereby aiding the pathogen in disease establishment.

Cyanobacterial lectins characteristics and their role as antiviral agents

Lectins are ubiquitous proteins/glycoproteins of non-immune origin that bind reversibly to carbohydrates in non-covalent and highly specific manner. These lectin-glycan interactions could be exploited for establishment of novel therapeutics, targeting the adherence stage of viruses and thus helpful in eliminating wide spread viral infections. Here the review focuses on the haemagglutination activity, carbohydrate specificity and characteristics of cyanobacterial lectins. Cyanobacterial lectins exhibiting high specificity towards mannose or complex glycans have potential role as anti-viral agents. Prospective role of cyanobacterial lectins in targeting various diseases of worldwide concern such as HIV, hepatitis, herpes, influenza and ebola viruses has been discussed extensively. The review also lays emphasis on recent studies involving structural analysis of glycan-lectin interactions which in turn influence their mechanism of action. Altogether, the promising approach of these cyanobacterial lectins provides insight into their use as antiviral agents.

New mycelial lectins from penicilli with complex carbohydrate specificity

Abstract In the current study, 55 Penicillium species were screened for lectin activity using erythrocytes of human ABO, pig, sheep, goat and rabbit. Only four Penicillium species, namely P. duclauxii, P. griseoroseum, P. proteolyticum and P. caseifulfum exhibited lectin activity, while crude undiluted mycelial extract of six species (P. aragonense, P. coralligerum, P. lagena, P. pinophilum, P. spinuloramigenum and P. miczynskii) showed weak haemagglutination. P. duclauxii, P. caseifulfum and P. proteolyticum lectins demonstrated non-specific agglutination towards human as well as animal erythrocytes, whereas P. griseoroseum lectin displayed specific agglutination activity only towards rabbit erythrocytes. Neuraminidase and protease treatment of erythrocytes showed an increase in lectin activity of P. duclauxii, P. griseoroseum and P. proteolyticum, whereas no effect occurred on lectin activity of P. caseifulfum. Lectin activity expressed after 5 days of cultivation in broth cultures of P. griseoroseum and P. proteolyticum exhibited a sharp decline after the 8th and 9th day, respectively. In P. caseifulfum and P. duclauxii broth cultures, lectin activity was expressed after 6 days of cultivation and demonstrated decline after the 7th and 8th day, respectively. A panel of 40 carbohydrates and glycoproteins was used to study their minimum inhibitory concentration capable of inhibiting lectin-induced haemagglutination. Lectin activity of P. duclauxii, P. proteolyticum, P. caseifulfum and P. griseoroseum was strongly inhibited by chondroitin-6-sulphate, thiogalactoside, bovine submaxillary mucin, porcine stomach mucin and fetuin. Owing to their enormous ability to discriminate sugars with high specificity, a myriad of lectins can be used as biotechnological tools for future research.

Lectins from red algae and their biomedical potential

Lectins are unique proteins or glycoproteins of non-immune origin that bind specifically to carbohydrates. They recognise and interact reversibly to either free carbohydrates or glycoconjugates, without modifying their structure. Lectins are highly diverse and widely distributed in nature and have been extensively reported from various red algae species. Numerous red algae species have been reported to possess lectins having carbohydrate specificity towards complex glycoproteins or high-mannose N-glycans. These lectin-glycan interactions further trigger many biochemical responses which lead to their extensive use as valuable tools in biomedical research. Thus, owing to their exceptional glycan recognition property, red algae lectins are potential candidate for inhibition of various viral diseases. Hence, the present report integrates existing information on the red algae lectins, their carbohydrate specificity, and characteristics of purified lectins. Further, the review also reports the current state of research into their anti-viral activity against various enveloped viruses such as HIV, hepatitis, influenza, encephalitis, coronavirus and herpes simplex virus and other biomedical activities such as anti-cancer, anti-microbial, anti-inflammatory, anti-nociceptive and acaricidal activities.

Purification and characterization of a mitogenic lectin from Penicillium duclauxii

Lectins are proteins/glycoproteins of non-immune origin which interact specifically and non-covalently with carbohydrate moieties on the cell surface. In this study, a lectin was purified from Penicillium duclauxii by ion-exchange chromatography on DEAE-Sepharose and gel filtration chromatography on a Sephadex G-100 column. An overall recovery of 94.11% and 60-fold purification was achieved. The purified lectin had a molecular weight of 54.9 kDa and was found to be heterogeneous as revealed by double band of sub-units with molecular mass of 21.13 kDa and 33.26 kDa, under reducing conditions. It is a glycoprotein with carbohydrate content of 3.95%. Lectin induced haemagglutination of erythrocytes was inhibited strongly by glycoproteins such as bovine submaxillary mucin, porcine stomach mucin and fetuin. The maximum haemagglutinating activity of P. duclauxii lectin was maintained after incubation at a temperature and pH range of 20-35 °C and 6.0-8.0, respectively. The haemagglutinating activity of P. duclauxii lectin was unaffected by EDTA and various metal ions. The purified P. duclauxii lectin exhibited maximum mitogenic activity towards mouse splenocytes at a concentration of 75 μg/mL. This manuscript reports a novel lectin from P. duclauxii with potent mitogenic activity towards mouse splenocytes.

Parallel implementation of Numerov's method based algorithm for singularly perturbed boundary value problems

In this paper, a parallel computational technique is proposed for solving self-adjoint singularly perturbed boundary value problems. After decomposing the domain into three non-overlapping subdomains, we devise three independent boundary-value problems and then using Numerovs scheme for the boundary regions and reduced solution for the regular region, we solve them using three different processors. We have implemented the proposed scheme on parallel machine and speed-ups along with maximum errors are computed to show the efficiency of the scheme.