Jatropha curcas hemagglutinin is similar to a 2S albumin allergen from the same source and has unique sugar affinities.

We have previously reported the purification and preliminary X-ray characterization of a hemagglutinin from the seeds of Jatropha curcas and, with the detailed sequencing information available now, we find that it is similar to a 2S albumin allergen isolated from the same source. Through a search of Jatropha genome database (http://www.kazusa.or.jp/jatropha/), we map it to the sequence id JcCA0234191 (now referred to as Jcr4S00619.70 in the new version, release 4.5) which has a conserved alpha amylase inhibitor/seed storage protein domain found in the 2S albumin allergens. The putative sequence of the small and large chains of the protein is assigned and the total mass of the two subunits matches with the intact mass 10 kDa determined through MALDI. The protein retains hemagglutination activity between pH 6-9 and up to 60 °C on heat treatment and its hemagglutination activity is inhibited by sialic acid and fetuin. Bioinformatics studies show that the isolated protein sequence clusters in close association with a 2S albumin from Ricinus communis in phylogeny analysis and has a conservation of the characteristic four disulfide linkage pattern. Hemagglutinins and lectins are known to have allergenic effects through their interaction with immunoglobulin E and histamine release and earlier studies have shown that this interaction can be inhibited by lectin-specific sugars. We hope this report bridges the plant allergens and hemagglutinins further for exploring possible mediation of allergenic activity through sialic acid and complex sugar interactions and generates further interest in the area.

Purification, crystallization and preliminary X-ray characterization of a haemagglutinin from the seeds of Jatropha curcas.

The plant Jatropha curcas (Euphorbiaceae) is an important source of biofuel from the inedible oil present in its toxic seeds. The toxicity arises from the presence of curcin, a ribosome-inactivating protein showing haemagglutination activity. In this communication, the purification, crystallization and preliminary X-ray characterization are reported of a small protein isolated from J. curcas seeds with a molecular mass of ~10 kDa that agglutinates rabbit erythrocytes. The protein was crystallized using the hanging-drop vapour-diffusion method and also by the microbatch method in 72-well HLA plates, using PEG 8000 as the precipitant in both conditions. X-ray diffraction data collected from the rod-shaped crystals were processed in the orthorhombic space group P2(1)2(1)2(1). The crystals diffracted to 2.8 Å resolution at 103 K.

A conserved human DJ1-subfamily motif (DJSM) is critical for anti-oxidative and deglycase activities of Plasmodium falciparum DJ1.

Plasmodium falciparum DJ1 (PfDJ1) belongs to the DJ-1/ThiJ/PfpI superfamily whose members are present in all the kingdoms of life and exhibit diverse cellular functions and biochemical activities. The common feature of the superfamily is the class I glutamine amidotransferase domain with a conserved redox-active cysteine residue, which mediates various activities of the superfamily members, including anti-oxidative activity in PfDJ1 and human DJ1 (hDJ1). As the superfamily members represent diverse functional classes, to investigate if there is any sequence feature unique to hDJ1-like proteins, sequences of the representative proteins of different functional classes were compared and analysed. A novel motif unique to PfDJ1 and several other hDJ1-like proteins, with the consensus sequence of TSXGPX5FXLX5L, was identified that we designated as the hDJ1-subfamily motif (DJSM). Several mutations that have been associated with Parkinson's disease are also present in DJSM, suggesting its functional importance in hDJ1-like proteins. Mutations of the conserved residues of DJSM of PfDJ1 did not significantly affect overall secondary structure, but caused both a significant loss (S151A and P154A) and gain (L168A) of anti-oxidative activity. We also report that PfDJ1 has deglycase activity, which was significantly decreased in its mutants of the catalytic cysteine (C106A) and DJSM (S151A and P154A). Episomal expression of the catalytic cysteine (C106A) or DJSM (P154A) mutant decreased growth rates of parasites as compared to that of wild type parasites or parasites expressing wild type PfDJ1. S151 appears to properly position the nucleophilic elbow containing C106 and P154 forms a hydrogen bond with C106, which could be a reason for the loss of activities of PfDJ1 upon their mutations. Taken together, DJSM delineates PfDJ1 and other hDJ1-subfamily proteins from the remaining superfamily, and is critical for anti-oxidative and deglycase activities of PfDJ1.

Heterologous expression, purification and characterization of L-type lectin homologue from Leishmania donovani.

Leishmaniasis, a disease of the developing world affects about 12 million people and has limited therapeutic interventions available. L-type lectins, Endoplasmic Reticulum Golgi Intermediate Compartment/Vesicular Integral Proteins (ERGIC-53/VIP36) are involved in protein sorting in luminal compartments of animal cells and are important for parasite biology. A lectin homologue was identified through a bioinformatics analysis of Leishmania genome and it was found to have N-terminal conserved carbohydrate recognition domain (CRD) and a unique C-terminal region rich in repetitive amino acids and a poly glutamine tract. The N-terminal CRD region was cloned and expressed in Escherichia coli, but gave an insoluble expression which was re-solubilized by on column refolding. The fold integrity was checked through CD, fluorescence and functional assay of hemagglutination activity using rabbit erythrocyte. Bioinformatics analysis identified 15 members from Tritryps (Leishmania spp., Trypanosoma spp.) and they separate out as a distinct clade in the global phylogenetic analysis of all ERGIC-53/VIP36 sequences downloaded from Uniprot. Our analysis shows that the extended C-terminal regions with repeats is unique to Tritryps and this repeat pattern is different in sequences from Leishmania spp. and Trypanosoma spp. and all these features make this protein an interesting candidate for further detailed studies.