Abstract
Although assimilation of inorganic nitrogen is a critical biochemical process for plant growth, the underlying regulatory mechanism has remained to be resolved. Here, we investigated nitrogen source-dependent gene expressions and its regulation by transcription factor(s) (TFs) in a red alga Cyanidioschyzon merolae. DNA microarray and Northern blot analyses showed that the expression of genes encoding glutamine synthase (GS), nitrate/ammonia transporter (NRT/AMT), nitrate/nitrite reductase (NR/SIRB), and MYB-type TF (CMJ282) were significantly increased in cells grown in culture containing nitrate as a nitrogen source, as compared with cells grown with ammonia. A consensus nucleotide sequence that is similar to GATA-type TF binding motif was found at those promoter regions, suggesting that GATA-type TF(s) contributes to the up-regulated transcriptions. We will also discuss the binding specificity of GATA-type TFs on the consensus nucleotide sequence and its cellular localization.
