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

Cloning, expression and characterization of a mucin-binding GAPDH from Lactobacillus acidophilus

Glyceraldehyde-3-phosphate dehydrogenase (GAPDH) is a ubiquitous enzyme involved in glycolysis. It is also referred to as a moonlighting protein as it has many diverse functions like regulation of apoptosis, iron homeostasis, cell-matrix interactions, adherence to human colon etc. apart from its principal role in glycolysis. Lactobacilli are lactic acid bacteria which colonize the human gut and confer various health benefits to humans. In the present study, we have cloned, expressed and purified the GAPDH from Lactobacillus acidophilus to get a recombinant product (r-LaGAPDH) and characterized it. Size exclusion chromatography shows that r-LaGAPDH exists as a tetramer in solution and have a mucin binding and hemagglutination activity indicating carbohydrate like binding adhesion mechanism. Fluorescence spectroscopy studies showed an interaction of r-LaGAPDH with mannose, galactose, N-acetylgalactosamine and N-acetylglucosamine with a Kd of 3.6±0.7×10(-3)M, 4.34±0.09×10(-3)M, 4±0.87×10(-3)M and 3.7±0.28×10(-3)M respectively. We hope that this preliminary data will generate more interest in further elucidation of the roles of GAPDH in the adhesion processes of the bacteria.

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.