Formate Dehydrogenase, an Enzyme of Anaerobic Metabolism, Is Induced by Iron Deficiency in Barley Roots1

Abstract

To identify the proteins induced by Fe deficiency, we have compared the proteins of Fe-sufficient and Fe-deficient barley (Hordeum vulgare L.) roots by two-dimensional polyacrylamide gel electrophoresis. Peptide sequence analysis of induced proteins revealed that formate dehydrogenase (FDH), adenine phosphoribosyltransferase, and the Ids3 gene product (for Fe deficiency-specific) increased in Fe-deficient roots. FDH enzyme activity was detected in Fe-deficient roots but not in Fe-sufficient roots. A cDNA encoding FDH (Fdh) was cloned and sequenced. Fdh expression was induced by Fe deficiency. Fdh was also expressed under anaerobic stress and its expression was more rapid than that induced by Fe deficiency. Thus, the expression of Fdh observed in Fe-deficient barley roots appeared to be a secondary effect caused by oxygen deficiency in Fe-deficient plants.In Fe-deficient calcareous soils graminaceous plants secrete mugineic acid family phytosiderophores, which are natural Fe chelators, from the roots (Takagi, 1976) to solubilize Fe required for plant growth. This Fe-acquisition mechanism in graminaceous plants is called strategy II and in nongraminaceous plants it is called strategy I (Takagi et al., 1984;Marschner et al., 1986). The pathway of the biosynthesis of mugineic acid family phytosiderophores has been established Nishizawa, 1987, 1989;Shojima et al., 1989Shojima et al., , 1990Mori et al., 1990;Ma and Nomoto, 1993). Among the enzymes involved in this biosynthetic pathway, Higuchi et al. (1994Higuchi et al. ( , 1996 purified nicotianamine synthase and Kanazawa et al. (1994) purified nicotianamine aminotransferase. Comparison of 2D profiles of proteins in barley (Hordeum vulgare L.) roots under Fesufficient and Fe-deficient conditions (Suzuki et al., 1995(Suzuki et al., , 1997 allowed us to identify a 36-kD protein that was specifically induced by Fe deficiency. In addition, several genes related to the Fe-deficiency response have been reported: Ids1 (Okumura et al., 1991), Ids2 (Okumura et al., 1994), and Ids3 (Nakanishi et al., 1993. In this study, we characterized several other proteins induced by Fedeficiency stress in barley roots, one of which was identified as FDH. FDH was induced not only by Fe deficiency but also by anaerobic stress. The relationship between Fe deficiency and anaerobic stress in barley roots is discussed. MATERIALS AND METHODS Plant Material and Growth ConditionsSeeds of barley (Hordeum vulgare L. cv Ehimehadaka no. 1) were germinated at room temperature on paper towels soaked with distilled water. Plants were transferred 4 d after germination to a plastic net floating on tap water at pH 5.5 in a greenhouse under natural light. On d 10, plants were transferred to a continuously aerated nutrient solution of the following composition: 0.7 mm K 2 SO 4 , 0.1 mm KCl, 0.1 mm KH 2 PO 4 , 2.0 mm Ca(NO 3 ) 2 , 0.5 mm MgSO 4 , 10 m H 3 BO 3 , 0.5 m MnSO 4 , 0.2 m CuSO 4 , 0.5 m ZnSO 4 , 0.01 m (NH 4 ) 6 Mo 7 O 24 , and 0.1 mm Fe-EDTA. The pH of the culture solution was adjusted to 5.5 da...

A Formate Dehydrogenase Confers Tolerance to Aluminum and Low pH

“…3 and 4). In barley roots, the expression of FDH is induced by iron deficiency, an induction that appears to be a secondary effect of the oxygen deficiency resulting from iron deficiency (Suzuki et al, 1998). It has also been proposed that glycolysis may play an important role in the FDH expression in response to abiotic stresses (Hourton-Cabassa et al, 1998).…”

Response of Arabidopsis to Iron Deficiency Stress as Revealed by Microarray Analysis

“…Fe-containing lipoxygenase (Hildebrand, 1989) and the storage protein ferritin (Gaymard et al, 1996) were also decreased in Fedeficient plants. In contrast, H ϩ -ATPase (Dell 'Orto et al, 2000), formate dehydrogenase (Suzuki et al, 1998), lysyl-tRNA synthetase (Giritch et al, 1997), and adenine phosphoribosyltransferase (Itai et al, 2000) were shown to be increased in expression or enzyme activity under Fe deficiency.…”

The role of formate in combatting oxidative stress

“…These enzymes have been reported with differing cofactor requirements, electron acceptors, substrates and cellular locations (Hourton Cabassa et al, 1998). The FDHs NAD-dependent which have been extensively studied in both bacteria, yeast and plants, have been widely utilized in industry for NADH regeneration (Alekseeva, Savin & Tishkov, 2011;Hoelsch et al, 2013;Suzuki et al, 1998) …”