Molecular cloning and characterization of a rice dehydroascorbate reductase

Abstract

Plant dehydroascorbate reductase (DHAR), which rereduces oxidized ascorbate to maintain an appropriate level of ascorbate, is very important, but no gene or cDNA for plant DHAR has been cloned yet. Here, we describe a cDNA for a rice glutathione-dependent DHAR (designated DHAR1). A recombinant Dhar1p produced in Escherichia coli was functional. The expression sequence tag database suggests that Dhar1p homologs exist in various plants. Furthermore, the rice Dhar1p has a low similarity to rat DHAR, although the rice enzyme has a considerably higher specific activity than the mammalian one. The mRNA level of DHAR1, the protein level of Dhar1p and the DHAR activity in rice seedlings were elevated by high temperature, suggesting the protection role of DHAR at high temperature.z 2000 Federation of European Biochemical Societies.

A proteomic approach in analyzing heat‐responsive proteins in rice leaves

“…Enhanced DHAR activity, against oxidative stress, has also been reported [52,53]. In addition, Urano et al [51] observed that DHAR activity rapidly increased in rice during heat stress and suggested that DHAR was involved in protection against high temperature.…”

“…The antioxidant activity of ascorbate is dependent upon its regeneration ability and DHAR catalyzes the re-reduction of dehydroascorbate to ascorbate by glutathione [51]. Enhanced DHAR activity, against oxidative stress, has also been reported [52,53].…”

Functional Divergence in the Glutathione Transferase Superfamily in Plants

“…These GST-like proteins fall into two distinct groups based on sequence similarity. One group, the AtDHARs, is indistinguishable from the dehydroascorbate reductases recently identified in rice and share the same functional activity (19). The other group classified as the new Lambda class of GSTs is similar to the In2-1 gene (22) and its wheat homologue Cla30 (23) previously identified as genes encoding proteins of unknown function that are induced by treatments with herbicide safeners (24).…”

“…In the first screen, the sequence of the recently reported human Omega class GST (hGSTO1) was used (18). In a BLAST search, the hGSTO1 polypeptide sequence identified a sequence (GenBank TM accession number AB037970) in rice (Oryza sativa) encoding a protein with dehydroascorbate reductase (DHAR) activity (19). Subsequent searches of the Arabidopsis genome data base with the rice DHAR identified four related sequences, which on alignment showed between 60 and 70% identity with the rice gene.…”

Relationship Between Relative Water Content and Ascorbate Redox Enzymes Activity in Lettuce Leaves Subjected to Soil Water Stress

“…(Conklin, 2001;Tokugana, et al, 2005 (Foyer and Halliwell, 1976;Foyer et al, 1983;Shigeoka et al, 2002 (Shigeoka et al, 2002;Shimaoka et al, 2000;Urano et al, 2000;Yoshimura et al, 2000). 이들 효소의 활성변화에 영향을 주는 인자로는 오존처리 , 관수온도 (Kang et al, 2001), 수분부족 (Kang, 2008) 등이 있으며, 시금치 (Morell et al, 1997), 완두콩 (Leterrier et al, 2005), 토마토 (Grantz et al, 1995) )를 측정하였 다 .…”