Abstract
Heme oxygenase–1 (HO1) is a stress protein induced by a variety of oxidative challenges. In this study, an NtHO1 gene coding for a tobacco (Nicotiana tabacum L.) HO1 was identified. The NtHO1 gene encodes an NtHO1 precursor of 32.1 kDa with a putative N-terminal plastid transit peptide. The three-dimensional structure of NtHO1 was modeled, and it showed a high degree of structural conservation compared with the known animal and bacterial HO1 crystal structures. Phylogenetic analysis revealed that NtHO1 clearly groups with the HO1-like sequences. The recombinant mature NtHO1 protein expressed heterologously in Escherichia coli was active in the conversion of heme to biliverdin IXα. The result of subcellular localization of NtHO1 confirmed the presence of a functional transit peptide and implied that the NtHO1 gene product is at least localized in the chloroplast. Expression analysis showed that NtHO1 was expressed in all tissues tested. Importantly, we found that NtHO1 expression could be induced by osmoti...
Published Version
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