Abstract
In animals and recently in plants, heme oxygenase-1 (HO1) has been found to confer protection against a variety of oxidant-induced cell and tissue injuries. In this study, a wheat (Triticum aestivum) HO1 gene TaHO1 was cloned and sequenced. It encodes a polypeptide of 31.7 kD with a putative N-terminal plastid transit peptide. The amino acid sequence of TaHO1 was found to be 78% similar to that of maize HO1. Phylogenetic analysis revealed that TaHO1 clusters together with the HO1-like sequences in plants. The purified recombinant TaHO1 protein expressed in Escherichia coli was active in the conversion of heme to biliverdin IXa (BV), and showed that the Vmax was 8.8 U·mg−1 protein with an apparent Km value for hemin of 3.04 μM. The optimum Tm and pH were 35 °C and 7.4, respectively. The result of subcellular localization of TaHO1 showed that the putative transit peptide was sufficient for green fluorescent protein (GFP) to localize in chloroplast and implied that TaHO1 gene product is at least localized in the chloroplast. Moreover, we found that TaHO1 mRNA could be differentially induced by the well-known nitric oxide (NO) donor sodium nitroprusside (SNP), gibberellin acid (GA), abscisic acid (ABA), hydrogen peroxide (H2O2) and NaCl treatments. Therefore, the results suggested that TaHO1 might play an important role in abiotic stress responses.
Highlights
A wide range of environmental stresses, such as salinity, drought, UV, and heavy metals exposure, are potentially harmful to plants
It was well established that heme oxygenases (HOs) could catalyze the oxidation of heme with molecular oxygen, which results in the formation of biliverdin-IXα (BV), carbon monoxide (CO) and free iron [4,5,6,7]
Abundant expressed sequence tags (ESTs) in public databases provide a source for the identification of new genes and for comparative analyses among different organisms
Summary
A wide range of environmental stresses, such as salinity, drought, UV, and heavy metals exposure, are potentially harmful to plants. Analysis of wheat expressed sequence tags (ESTs) generated from various tissues during plant development or upon different stress conditions gives insights into the transcribed portions of the genome. In this test, to get first insight into the role of wheat HO1, we reported on molecular cloning and characterization of a HO1 cDNA from wheat (named as TaHO1). The characterization of TaHO1 will provide insight into the physiological processes of stress responses in wheat plants
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