The circadian system of Chlamydomonas reinhardtii

Abstract

In the unicellular eukaryotic green alga Chlamydomonas reinhardtii, several circadian rhythms have been physiologically well characterised. Recently, the entire nuclear, chloroplast and mitochondrial genomes of this alga have been sequenced, and about 200 000 expressed sequence tags have been created. Therefore, functional proteomics of the circadian system has been initiated and has resulted in the identification of novel components of the circadian system (a protein disulfide isomerase and a tetratricopeptide repeat protein). Furthermore, comparative analysis of the C. reinhardtii genome with known clock-related genes from other model organisms reveals that some photoreceptors and especially clock-related kinases and phosphatases are well conserved in C. reinhardtii. Several circadian expressed genes have been identified in C. reinhardtii, whose temporal expression is controlled at the transcriptional level. Also, a circadian RNA-binding protein (CHLAMY 1) has been characterised. It represents a novel type of RNA-binding protein and mediates circadian control at the post-transcriptional level. Its circadian binding activity appears to be controlled by differential multi-protein complexes.

Keywords:

• Circadian rhythm
• Chlamydomonas reinhardtii
• functional proteomics
• gene expression
• RNA-binding protein

Acknowledgments

The work in our lab was supported by the Deutsche Forschungsgemeinschaft.