Chlamydomonas induces a carbon concentrating mechanism under limiting CO2, which is associated with the relocalisation of Rubisco to a chloroplast microcompartment known as the pyrenoid. This project aims to understand whether Rubisco aggregations occurs directly (as part of specific small subunit alpha helix interactions), or is associated with a linker protein, as well as other transcriptional or post-translational modifications. The work will involve: (i) Testing the importance of alternative splicing in regulating the algal CCM. We have preliminary evidence that at least one of the key algal CCM components undergoes alternative splicing in response to specific changes in CO2 concentration. Using RT-PCR on mRNA extracted from strains grown under a range of contrasting conditions, the student will test at what CO2 level splice variants form, and what other known CCM genes are under a similar regulation; (ii) Testing the role of cis-elements in regulating the algal CCM, for genes of interest. Using 5’ nested deletions, we will generate constructs to determine the minimal 5’UTR sequence requested for expression of a reporter gene under CCM induced conditions. Other ongoing work will also involve RNAseq and bioinformatics as we compare CCM gene expression and search for new regulatory elements of the CCM. As part of a large international consortium, (see http://cambridgecapp.wordpress.com/), we are identifying new CCM components for introduction into Arabidopsis by colleagues at JIC. This is a first step towards engineering enhanced photosynthesis in a crop plant, as an alternative to the C4 pathway.
- Meyer MT and Griffiths H (2013) Origins and Diversity of Eukaryotic CO2-Concentrating Mechanisms: Lessons for the Future J exp Bot, 64, 769–786
- Meyer, M., Genkov, T., Skepper, J.N., Jouhet, J., Mitchell, M.C., Spreitzer, R.J. and Griffiths, H. (2012) Rubisco Small Subunit Alpha-Helices Control Pyrenoid Formation in Chlamydomonas. PNAS (USA) 109, 19474-19479.
- Price G.D., Pengelly J.J.L., Forster B., Du J., Whitney S.M., von Caemmerer S., Badger M.R., Howitt S.M. & Evans J.R. 2012. The cyanobacterial CCM as a source of genes for improving photosynthetic CO2 fixation in crop species. Journal of experimental Botany 64, 753-768.