Evolutionary, gene ontology and physiochemical relationships in LEA proteins of Oryza sativa indica: Detailed computational sequence-based insight

Abstract

Expedition into anti-aggregating proteins present in the plant kingdom led to discovery of Late embryogenesis abundant (LEA) proteins, a group of versatile, hydrophilic, heat stable, low molecular weight proteins that play a significant role in abiotic stress tolerance in plants. In plant, LEA proteins have been detected in various regions such as in roots, stems and seedlings. The expression of LEA proteins has been observed to get highly elevated in stressed conditions, especially drought, temperature fluctuations and salinity. This study identified three different LEA designated domains in Oryza sativa indica (Indian rice), namely LEA3, LEA4 and LEA6, and focused on which other organisms have these LEA domains with >50% sequence identity than that of Oryza sativa indica. Diversity in physiochemical properties, structure and gene ontology were observed among LEA3, LEA4 and LEA6 domain-containing proteins along with their genomic distribution and level of expression. An inverse relationship between disorder and coil content, while a direct relationship between disorder and helix content were observed in these LEA domain-containing proteins. Higher content of helix breakers like proline and glycine and less helix former like alanine, glutamate and lysine resulted in low helix and high coil in LEA6 domain-containing proteins. While the opposite trend was observed in helix-rich LEA4 domain-containing protein with a high content of helix formers and very low content of helix breakers. Phylogenetic study classified the LEA domain containing proteins into two clusters with LEA4 and LEA6 domain-containing proteins in the same group, even though they have significant structural diversity and LEA3 domain-containing proteins in the other cluster. This computational study holds an insight in agricultural biotechnology by highlighting the role of LEA domains in abiotic stress response and would further instigate detailed study and comparative analyses of LEA domains of other cereal crops and advancement in the field of genetic engineering.