Isolation and characterization of IDI2, a new Fe-deficiency-induced cDNA from barley roots, which encodes a protein related to the α subunit of eukaryotic initiation factor 2B (eIF2Bα)

A new Fe-deficiency-inducible cDNA, IDI2, was isolated from Fe-deficient barley roots using the cDNA MACRO Array Technique. Accumulation of IDI2 transcripts in barley roots was strongly correlated with iron nutritional status. IDI2 encoded a protein with a low similarity to the or subunit of eukaryotic initiation factor 2B (eIF2B alpha), In addition, many hypothetical proteins homologous to IDI2 were also found in a database search. These proteins had limited similarity to eIF2B alpha as well as IDI2. It has been reported that these eIF2B alpha -like proteins (eIF2B alpha/beta/delta -LPs) are a family that is distinct from the eIF2B alpha/beta/delta family and widely distributed in the archaea, bacteria, and eukarya. A phylogenic analysis revealed that IDI2 is the first member of the eIF2 beta alpha -LP family to be found in higher plants. A possible role of IDI2 protein in regulating protein synthesis in Fe-deficient barley roots is proposed.