Molecular characterization and In silico analysis of Sorghum Panallergens: Profilin and Polcalin

In India, 20-30% of the human population suffer from allergic rhinitis and 15% of them develop asthma. Plant pollens are one of the causative aeroallergens and are mixture of a number of molecules including major and minor allergens (Panallergens). Profilin and polcalcin are the known pollen specific panallergens. Allergenicity of the Sorghum plant in Andhra Pradesh was found to be 54.9%. But the allergens responsible have not been characterized well. This study highlights identification and molecular characterization of Sorghum bicolor profilin (Sorb PF) and S. bicolor polcalcin (Sorb PC) allergen genes based on homology. The coding sequences of the two genes were PCR amplified from the cDNA constructed from Sorghum pollen total RNA. The gene sequences were deposited in NCBI, KC427126 and KC427125. Recombinantly expressed histidine tag (His-tag) purified Sorghum polcalcin and profilin confirmed 9 and 14 kDa proteins, respectively. Based on multiple sequence alignment and phylogenetic analysis, Sorghum polcalcin and profilin were found to be closely related with Cynodon dactylon, Phleum pratense and Oryza sativa grass species. In silico Algpred based screening of SorbPF and SorbPC showed an allergenicity score of 1.149 and 0.879, respectively. The structure of two Ef-hand sequences (DTNGDGKISLSEL and DTDGDGFIDFNEF) of SorbPC showed an exact match with Phlp7. It is concluded that Sorghum recombinant profilin and polcalcin proteins can be of potential use in developing diagnostic kits for allergenicity to Sorghum pollen grains.