Abstract
Chloroplasts have their own genome and gene expression systems derived from endosymbiosis of ancestral cyanobacteria. In the course of subsequent evolution, chloroplasts lost their autonomy and most regulatory systems became under nuclear control. In this work, we used the unicellular red alga Cyanidioschyzon merolae. This alga shows ancestral characteristics in many aspects including chloroplast genome structure and transcription regulation. Therefore, some regulatory systems in C. merolae show more autonomous features than those in higher plants.
Here we performed chromatin immunoprecipitation (ChIP) assay to understand light-dependent transcription regulation. Previously, we found transcription of ycf27 and psbD is specifically activated under light condition. Ycf27, one of the chloroplast-encoded transcription factors, is a candidate in this regulation. We performed ChIP assay and found that Ycf27 actually binds to those promoters and this binding depends on light-condition. This suggests that transcription of particular genes is regulated by chloroplast-specific mechanisms independent of the nucleus.
