Cloning and analysis of physico-chemical and structural characteristics of a h-Type thioredoxin gene, belonging to subgroup I from grape (Vitis vinifera L. cv. Askari) berry tissue

thioredoxins (Trxs) are small ubiquitous disulfide reductases that are present in all organisms from prokaryotes to higher eukaryotes and involve in the cell redox regulation. In contrast to other organisms, plants contain six different Trx types: f, m, x, y, o and h that only h type Trx has been the most extensively studied and consists of multiple forms that involved in different processes including cellular protection against oxidative stress. Cloning of a h-type thioredoxin gene was performed from grape (Vitis vinifera L. cv. Askari) berry tissue by reverse transcription polymerase chain reaction (RT-PCR) technique, and then its physico-chemical, structural and phylogenetic characteristics was analyzed. The nucleotide sequence of open reading frame, called VvTrx h4, was revealed a 345 bp long with a deduced amino acid of 114 residues, possessing a WCGPC active site. The estimated molecular mass and the predicted isoelectric point of the deduced polypeptide were 12.76 kDa and 5.22 respectively. Prediction of three-dimensional structure of VvTrx h4 using the crystal structure of AtTrx h1 from Arabidopsis was consistent with these predictions and with five β-sheets and four α helixes, contains the thioredoxin fold. The deduced protein sequence was shown a high similarity to thioredoxins h isolated from plants, e.g. Populus trichocarpa (89% similar with Pth3) and Citrus cv. Shiranuhi 86% similar with Csh). Phylogenetic studies using of thioredoxin from other plants was indicated that VvTrx h4 gene is a thioredoxin h, belonging to the subclass IA from subgroup I.