RRC ID 31090
Author Minoda A, Weber AP, Tanaka K, Miyagishima SY.
Title Nucleus-independent control of the rubisco operon by the plastid-encoded transcription factor Ycf30 in the red alga Cyanidioschyzon merolae.
Journal Plant Physiol
Abstract Chloroplasts originated from a cyanobacterium, which was engulfed by a primitive eukaryotic host cell. During evolution, chloroplasts have largely lost their autonomy due to the loss of many genes from their own genomes. Consequently, expression of genes encoded in the chloroplast genome is mainly controlled by the factors transferred from the cytosol to chloroplasts. However, chloroplast genomes of glaucophytes and red algae have retained some transcription factors (hypothetical chloroplast open reading frame 27 to 30 [Ycf27-Ycf30]) that are absent from green algae and land plants. Here, we show that the red algal chloroplast up-regulates transcription of the Rubisco operon rbcLS-cbbX via Ycf30 independently of nuclear control. Light-induced transcriptional activation of the Rubisco operon was observed in chloroplasts isolated from the red alga Cyanidioschyzon merolae. The activation was suppressed by 3-(3,4-dichlorophenyl)-1,1-dimethylurea. These results suggest that chloroplast autonomously regulates transcription of the Rubisco operon in response to the activation of photosynthesis driven by the light. Transcriptional activation of the Rubisco operon was specifically repressed by the addition of anti-Ycf30 antibodies. Furthermore, reduced NADP, ribulose-1,5-bisphosphate, and 3-phosphoglyceric acid triggered the up-regulation of Rubisco transcription in the dark, and the activation was dependent on Ycf30. Thus, red algal chloroplasts have retained a nucleus-independent transcriptional regulation of the Rubisco operon to respond to environmental changes. The autonomous system would have been necessary for the initial fixation of cyanobacterial photosynthesis in the ancient nonphotosynthetic eukaryotic host. It has remained functional in the red algal chloroplast over evolutionary time.
Volume 154(3)
Pages 1532-40
Published 2010-11-1
DOI 10.1104/pp.110.163188
PII pp.110.163188
PMID 20813908
PMC PMC2971626
MeSH Cell Nucleus / metabolism Chloroplasts / genetics Gene Expression Regulation, Plant Light Operon* Plant Proteins / genetics Plant Proteins / metabolism* Promoter Regions, Genetic Rhodophyta / genetics* Rhodophyta / metabolism Ribulose-Bisphosphate Carboxylase / genetics Ribulose-Bisphosphate Carboxylase / metabolism* Transcription Factors / genetics Transcription Factors / metabolism* Transcriptional Activation
IF 6.902
Times Cited 17
Algae NIES-3377