Molecular characterization, heterologous expression and resistance analysis of OsLEA3-1 from Oryza sativa

Abstract

Late embryogenesis abundant (LEA) proteins in organisms are closely associated with resistance to abiotic stresses. Here we characterized a rice LEA protein, OsLEA3-1, by bioinformatics analysis and heterologous expression in Escherichia coli. Bioinformatics analysis showed that OsLEA3-1 contains a 603-bp open reading frame encoding a putative polypeptide of 200 amino acids, which contains a “LEA_4” motif at positions 5–48 and belongs to a typical group 3 LEA. OsLEA3-1 polypeptide is rich in Ala, Lys, and Thr, but depleted in Cys, Pro, and Trp residues; and is strongly hydrophilic. Secondary structure prediction showed that OsLEA3-1 polypeptide contained an α-helical domain in positions 4-195 but not any β-sheet domain. OsLEA3-1 gene can express in shoot and root of germinating seeds, seedling, panicles, mature embryo, seed, and callus; and was also up-regulated by ultraviolet (UV), heat, cold, salt, and emergency drought. OsLEA3-1 gene was introduced into E. coli. A fusion protein of about 28.03 kDa was expressed in recombinant E. coli cells after the induction by isopropylthio-β-D-galactoside. Compared with control E. coli cells harbouring pET30a, the accumulation of the OsLEA3-1 fusion protein increased the tolerance of the E. coli recombinants under diverse abiotic stresses: high salinity, metal ions, hyperosmotic, heat, and UV radiation. The OsLEA3-1 has the ability to protect the lactate dehydrogenase activity under heating, drying, and MnCl2 treatment in vitro. The findings suggested that the OsLEA3-1 gene may contribute to the ability of adapting to stressful environments of plants.