Lectin genes and their mature proteins: Still an exciting matter, as revealed by biochemistry and bioinformatics analyses of newly reported proteins

Two new lectins were purified through affinity chromatography after crude extract preparation under high ionic strength. The hemagglutinating activity of these lectins from the seeds of the legumes Dioclea bicolor (DBL) and Deguelia scandens (DSL) was inhibited by galactose and glucose, respectively, and the molecular masses were estimated at 24 and 22kDa (via SDS-PAGE), respectively. The alignment of internal peptides of DBL (MS/MS) with known protein sequences revealed similarity to other legume lectins. The N-terminal amino acid sequence of DSL also aligned with legume lectins. Cross-similarities among the two studied lectins were observed only after sequence permutation. More than a dozen lectins have been reported for the genus Dioclea but none that recognize galactose. DSL is the first lectin reported for the Deguelia genus in the tribe Millettieae. With the aid of bioinformatics tools and searches for genome/transcriptome information about closely related sequences, new lectin members of Millettieae were also identified. Electrophoresis profiling and amino acid sequence analysis suggested that DBL-Gal and DSL do not undergo post-transcriptional ConA-like circular permutation. Molecular modeling of the deduced amino acid sequences of the Millettieae lectins suggested that the overall folding of the monomeric structures of legume lectins is conserved. This and other recent studies highlight native plants of the Amazon as renewed sources of lectins. © 2015 Elsevier Ltd

Purification and characterization of a lectin of the swartzieae legume taxa

This work aimed at describing the first biochemical and structural data of a lectin belonging to Swartzieae, a primitive Legume Taxa. A lactose-binding seed lectin (SLL) was purified by affinity chromatography of crude saline extracts of Swartzia laevicarpa on immobilized lactose. The SLL agglutinated rabbit erythrocytes but not rat or human (A, B, O) erythrocytes. Lectin activity was retained after heating at 100 °C for 15 min and was best inhibited by Nacetylgalactosamine, lactose and galactose. The lectin exhibited a single electrophoretic pattern that corresponded to a molecular mass of 29,000 Da, which was confirmed by MS analysis. In addition, the lectin reacted positively with Schiff's reagent. The unique N-terminal amino acid sequence (39 residues) and the internal peptide sequence were determined by Edman degradation and MS/MS, respectively. The sequencing revealed complete homology of the SLL with legume lectins belonging to primitive groups (Dalbergieae and Sophoreae). The SLL (at 1 mg/ml) did not exhibit antifungal activity against various phytopathogens or cytotoxicity (at 100 μg/ml) towards different cancer cell lines. © 2012 Bentham Science Publishers

ClCPI, a cysteine protease inhibitor purified from Cassia leiandra seeds has antifungal activity against Candida tropicalis by inducing disruption of the cell surface

Infections caused by Candida tropicalis have increased significantly worldwide in parallel with resistance to antifungal drugs. To overcome resistance novel drugs have to be discovered. The objective of this work was to purify and characterize a cysteine protease inhibitor from the seeds of the Amazon rainforest tree Cassia leiandra and test its inhibitory effect against C. tropicalis growth. The inhibitor, named ClCPI, was purified after ion exchange and affinity chromatography followed by ultrafiltration. ClCPI is composed of a single polypeptide chain and is not a glycoprotein. The molecular mass determined by SDS-PAGE in the absence or presence of β-mercaptoethanol and ESI-MS were 16.63 kDa and 18.362 kDa, respectively. ClCPI was stable in the pH range of 7.0–9.0 and thermostable up to 60 °C for 20 min. ClCPI inhibited cysteine proteases, but not trypsin, chymotrypsin neither alpha-amylase. Inhibition of papain was uncompetitive with a Ki of 4.1 × 10 −7 M and IC 50 of 8.5 × 10 −7 M. ClCPI at 2.6 × 10 −6 M reduced 50% C. tropicalis growth. ClCPI induced damages and morphological alterations in C. tropicalis cell surface, which led to death. These results suggest that ClCPI have great potential for the development of an antifungal drug against C. tropicalis. © 201

cDNA cloning, molecular modeling and docking calculations of L-type lectins from Swartzia simplex var. grandiflora (Leguminosae, Papilionoideae), a member of the tribe Swartzieae

The genus Swartzia is a member of the tribe Swartzieae, whose genera constitute the living descendants of one of the early branches of the papilionoid legumes. Legume lectins comprise one of the main families of structurally and evolutionarily related carbohydrate-binding proteins of plant origin. However, these proteins have been poorly investigated in Swartzia and to date, only the lectin from S. laevicarpa seeds (SLL) has been purified. Moreover, no sequence information is known from lectins of any member of the tribe Swartzieae. In the present study, partial cDNA sequences encoding L-type lectins were obtained from developing seeds of S. simplex var. grandiflora. The amino acid sequences of the S. simplex grandiflora lectins (SSGLs) were only averagely related to the known primary structures of legume lectins, with sequence identities not greater than 50–52%. The SSGL sequences were more related to amino acid sequences of papilionoid lectins from members of the tribes Sophoreae and Dalbergieae and from the Cladratis and Vataireoid clades, which constitute with other taxa, the first branching lineages of the subfamily Papilionoideae. The three-dimensional structures of 2 representative SSGLs (SSGL-A and SSGL-E) were predicted by homology modeling using templates that exhibit the characteristic β-sandwich fold of the L-type lectins. Molecular docking calculations predicted that SSGL-A is able to interact with D-galactose, N-acetyl-D-galactosamine and α-lactose, whereas SSGL-E is probably a non-functional lectin due to 2 mutations in the carbohydrate-binding site. Using molecular dynamics simulations followed by density functional theory calculations, the binding free energies of the interaction of SSGL-A with GalNAc and α-lactose were estimated as −31.7 and −47.5 kcal/mol, respectively. These findings gave insights about the carbohydrate-binding specificity of SLL, which binds to immobilized lactose but is not retained in a matrix containing D-GalNAc as ligand. © 2017 Elsevier Lt

Paediatric COVID-19 mortality: a database analysis of the impact of health resource disparity

Background The impact of the COVID-19 pandemic on paediatric populations varied between high-income countries (HICs) versus low-income to middle-income countries (LMICs). We sought to investigate differences in paediatric clinical outcomes and identify factors contributing to disparity between countries.Methods The International Severe Acute Respiratory and Emerging Infections Consortium (ISARIC) COVID-19 database was queried to include children under 19 years of age admitted to hospital from January 2020 to April 2021 with suspected or confirmed COVID-19 diagnosis. Univariate and multivariable analysis of contributing factors for mortality were assessed by country group (HICs vs LMICs) as defined by the World Bank criteria.Results A total of 12 860 children (3819 from 21 HICs and 9041 from 15 LMICs) participated in this study. Of these, 8961 were laboratory-confirmed and 3899 suspected COVID-19 cases. About 52% of LMICs children were black, and more than 40% were infants and adolescent. Overall in-hospital mortality rate (95% CI) was 3.3% [=(3.0% to 3.6%), higher in LMICs than HICs (4.0% (3.6% to 4.4%) and 1.7% (1.3% to 2.1%), respectively). There were significant differences between country income groups in intervention profile, with higher use of antibiotics, antivirals, corticosteroids, prone positioning, high flow nasal cannula, non-invasive and invasive mechanical ventilation in HICs. Out of the 439 mechanically ventilated children, mortality occurred in 106 (24.1%) subjects, which was higher in LMICs than HICs (89 (43.6%) vs 17 (7.2%) respectively). Pre-existing infectious comorbidities (tuberculosis and HIV) and some complications (bacterial pneumonia, acute respiratory distress syndrome and myocarditis) were significantly higher in LMICs compared with HICs. On multivariable analysis, LMIC as country income group was associated with increased risk of mortality (adjusted HR 4.73 (3.16 to 7.10)).Conclusion Mortality and morbidities were higher in LMICs than HICs, and it may be attributable to differences in patient demographics, complications and access to supportive and treatment modalities