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- Title
Cloning and Characterization of a Heme Oxygenase-2 Gene from Alfalfa ( Medicago sativa L.).
- Authors
Fu, Guang-Qing; Jin, Qi-Jiang; Lin, Yu-Ting; Feng, Jian-Fei; Nie, Li; Shen, Wen-Biao; Zheng, Tian-Qing
- Abstract
Heme oxygenase (HO, EC 1.14.99.3) catalyzes the oxidation of heme and performs vital roles in plant development and stress responses. Two HO isozymes exist in plants. Between these, HO-1 is an oxidative stress-response protein, and HO-2 usually exhibited constitutive expression. Although alfalfa HO-1 gene ( MsHO1) has been investigated previously, HO2 is still poorly understood. In this study, we report the cloning and characterization of HO2 gene, MsHO2, from alfalfa ( Medica sativa L.). The full-length cDNA of MsHO2 contains an ORF of 870 bp and encodes for 290 amino acid residues with a predicted molecular mass of 33.3 kDa. Similar to MsHO1, MsHO2 also appears to have an N-terminal transit peptide sequence for chloroplast import. Many conserved residues in plant HO were also conserved in MsHO2. However, unlike HO-1, the conserved histidine (His) required for heme-iron binding and HO activity was replaced by tyrosine (Tyr) in MsHO2. Further biochemical activity analysis of purified mature MsHO2 showed no HO activity, suggesting that MsHO2 may not be a true HO in nature. Semi-quantitative RT-PCR confirmed its maximum expression in the germinating seeds. Importantly, the expression levels of MsHO2 were up-regulated under sodium nitroprusside (SNP) and HO (especially) treatment, respectively.
- Subjects
OXIDATION; HEME; HISTIDINE; AMINO acids; OXIDATIVE stress
- Publication
Applied Biochemistry & Biotechnology, 2011, Vol 165, Issue 5/6, p1253
- ISSN
0273-2289
- Publication type
Academic Journal
- DOI
10.1007/s12010-011-9343-7