Cloning and Structural Analysis of an Indian Little Millet (Panicum sumatrense) Zein-Like Storage Protein: Implications for Molecular Assembly

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S. Sivakumar^1*, O. L. Franco², B. Thayumanavan¹, A. M. Murad², A. Manickam¹, M. Mohan¹, and M. Mridula³

¹Center for Plant Molecular Biology, Tamil Nadu Agricultural University, Coimbatore-641 003, India; fax: +91-422-551-1454; E-mail: subarayansivakumar@yahoo.com

²Centro de Analises Proteomicas e Bioquímicas, Pós-Graduação em Ciências Genômicas e Biotecnologia, Universidade Católica de Brasília, Brasilia - DF, Brazil; fax: +55-61-3347-4797; E-mail: ocfranco@pos.ucb.br

³Project Trainee, Bioinformatics Center, Indian Institute of Science, Bangalore, India

^* To whom correspondence should be addressed.

Received January 18, 2006; Revision received May 30, 2006

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Zeins are prolamin storage proteins that accumulate in kernel endosperm of several cereals. For cloning of genes coding for zein-like proteins that accumulate in enhanced quantities in the filling stages of little millet (Panicum sumatrense Roth.) developing grains, RT-PCR was performed using specific primers. A 750-bp cDNA was directly sequenced and in silico analysis showed high identity degree to alpha-prolamins. This family is composed of zeins from Zea mays, coixins from Coix lachryma-jobi, and alpha-kafirins from Sorghum bicolor. The putative conserved domain of zein-like proteins was identified by primary structure comparisons. Furthermore, threading analyses indicated that the millet zein-like protein forms an anti-parallel alpha-helical hairpin with two opposite surfaces: one hydrophobic and the other hydrophilic that probably could be involved in protein storage assembly. Knowledge about zein-like alpha-prolamins in little millet will lead to cloning and transfer of this gene to other major food crops, such as cereals and legumes, with inferior nutritional quality for monogastric animals.

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KEY WORDS: homology searches, molecular modeling, Indian little millet, zein, phylogenetic relationships

DOI: 10.1134/S0006297906110034

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