Molecular cloning and protein structure prediction of barley (<I>Hor-deum vulgare</I> L.) <I>Dhn6</I> gene and its expression pattern under dehydration conditions

Dehydrins (DHNs), proteins with protective functions encoded by the late embryogenesis abundant (LEA), are differentially up-regulated at the transcriptional level under environmental stresses such as water deficit, salinity, and low temperature or in response to ABA. Data involving protein structure and expression of dehydrins could elucidate their functional roles under dehydration conditions in plants. Dhn6 gene of 1767 bp with an intron (92 bp) in six-rowed barley, a member of LEA D11, was cloned into pMD18-T vector in the present study. It shared 93.18% identity with Hordeum vulgare ssp. vulgare (GenBank accession: AF043091), encoding a protein composed of 523 amino acid residues with the predicted molecular weight of 49.68 kDa and the theoretical isoelectric point of 8.04. Analyses of domain and structure indicated that the protein was dominantly composed of 83% hydrophillic amino acid residues, with numerous imperative curls and three loosed helixes. Three-dimensional measurement revealed that the water-soluble lipid-associating protein was attributed to its twisted cable formed by reverse paralleled chains. Moreover, the putative amphipathic α-helices formed by K-segments might play roles in protecting membrane structure in barley. Significantly, relatively high accumulations of Dhn6 gene were detected after 8 h of water deficit by real-time quantitative RT-PCR. These results possibly suggested that the accumulation of Dhn6 gene could be critical for resistant dehydration in plants.