N-terminal amino acid sequences of prolamins encoded by the alleles at the Pro1 and Pro2 loci in foxtail millet, Setaria italica (L.) P. Beauv.

Abstract

N-terminal amino acid sequences of six prolamins encoded by seven alleles at two loci, Pro1 and Pro2, of foxtail millet (Setaria italica (L.) P. Beauv.) were analyzed and compared with other prolamins of subfamily Panicoideae. Based on the N-terminal amino acid sequences, band 3 (the prolamin purified from band 3) which is controlled by an allele at the Pro1 locus and bands 1, 2, 4, 5 and 6 which are controlled by alleles at the Pro2 locus could be classified into three groups. Band 3 was found to be homologous to the prolamin of pearl millet (Pennisetum americanum) and is designated as the "pennisetin-like prolamin". Bands 2 and 4, and bands 1, 5 and 6 were subdivided into "x-type prolamin" and "y-type prolamin". Both of the x-type and y-type prolamins showed homology with prolamin of Echinochloa crus-galli and α-zein-like prolamins of maize, sorghum and Job's tears. Therefore, these prolamins were designated as "α-zein-like prolamin". These results suggest that alleles at the Pro1 locus and those at the Pro2 locus have not arisen from an identical ancestral gene, and that the Pro2 locus comprise two tightly linked genes, which encode similar prolamins. Hypotheses on the diversification of alleles at the Pro2 locus are discussed based on the N-terminal amino acid sequences of the respective bands, combinations of bands controlled by the alleles, and frequencies of the alleles.

Functional and phylogenetic analysis of prolamin proteins of foxtail millet using computational approaches

“…Low lysine and tryptophan concentration degrades the nutritional quality of the prolamin proteins. A study reported that N-terminal amino acid sequences of six prolamin gene encoded by alleles present in Pro1 and Pro2 of foxtail millet were classified into three groups which were homologous to prolamins of pearl millet, Echinochloa crusgalli and α-zein of maize, sorghum (Nakayama et al, 1999) [16] . Minor millets are renowned for their high-quality proteins and nutritional benefits.…”