Cloning and structural analysis of a cDNA clone encoding glycinin (Gly-1) seed storage protein of peanut

A cDNA clone (peanut Gly-1) encoding for glycinin protein was isolated from the immature seeds (from yellow-1 maturity pods) and characterized. The clone spanning a total of 1836 bp, predicted protein of 529 amino acid residues with a calculated mass of 60,447.61 Da. Peanut Gly-1 sequence comparison shows high level of sequence homology with other two peanut glycinin (arachin) genes [Ara h3 (95%) and Ara h4 (94%)] and glycinin (legumin) genes of other legumes such as soybean, broad bean, French bean and pea etc., both at nucleotide (67 to 69%) and amino acid (60 to 63%) levels. The N- and C-terminals of peanut Gly-1 are highly conserved with other glycinin genes; central region of the gene possess three variable regions, which also show conservation with other glycinin genes. peanut glycinin-1 gene deciphers 11S type A seed storage protein. Mapping for conserved domains indicate that Peanut Gly-1 consists of bi-cupin domain. RNA gel blot studies demonstrate that the gene expressed during embryo development that is transcriptionally activated early in embryogenesis (white pod maturity) and is repressed late in seed maturation (orange pod maturity stage). Peanut Gly-1 does not express in other tissues like leaf, stem, root, flower, pegs or post germinating seedlings.

Keywords
arachin, Arachis hypogaea, cupin superfamily, glycinin, legumins, peanut, seed storage protein.