In-depth characterization of the CES regulation coupling Rubisco large subunit synthesis and assembly in Ch. reinhardtii

PI:  Katia Wostrikoff

Biologie du chloroplaste et perception de la lumière chez les micro-algues

2-year contract

Host laboratory “Chloroplast Biology and Light-sensing in Microalgae”, headed by Dr. Angela Falciatore, and adjunct director Dr. Yves Choquet.

 

The host laboratory has a long-lasting expertise in photosynthesis, chloroplast biology and microalgal research and the project aims studying the evolution of energy-producing organelles of bacterial ancestry.

Following endosymbiosis and massive gene transfer from organelles to nucleus, chloroplasts and mitochondria developed regulatory feedback loops coupling the translation of some of their genes to the assembly of their products into the multimeric photosynthetic and respiratory complexes of dual genetic origin. This regulation, coined CES process (for control by epistasy of synthesis), prevents the wasteful synthesis of unassembled subunits, and allows fine-tuning the translation of organelle genes to the assembly of their products.

The recruited researcher will further explore the CES process coupling RuBisCO chloroplast and nuclear encoded subunits -LS and SS- synthesis and assembly in the green microalga Chlamydomonas reinhardtii. In plants and green algae, the biogenesis of Rubisco has proven to be quite complex. The synthesis of the chloroplast-encoded LS subunit requires at least one nucleus-encoded organellar trans-acting factor and at leas 5 chaperones for its folding, stabilization, oligomerization into a tetramer of dimers and subsequent assembly with SS, to yield the LS8SS8 complex. We recently determined that the LS8 octamer, bound to at least one of the chaperone, acts as a regulator of LS synthesis.

The postdoctoral project aims at I) identifying the components of this CES regulatory complex, possibly including RNA, II) understand the requirement for chaperones in the CES biogenesis pathway, and III) test whether CES process is a post-endosymbiotic innovation.

Wietrzynski, W., Traverso, E., Wollman, F.A., and Wostrikoff, K. (2021). The state of oligomerization of Rubisco controls the rate of synthesis of the Rubisco large subunit in Chlamydomonas reinhardtii. Plant Cell 33, 1706-1727.

Majeran, W., Wostrikoff, K., Wollman, F.A., and Vallon, O. (2019). Role of ClpP in the Biogenesis and Degradation of RuBisCO and ATP Synthase in Chlamydomonas reinhardtii. Plants (Basel, Switzerland) 8.

Wostrikoff, K., Clark, A., Sato, S., Clemente, T., and Stern, D. (2012). Ectopic expression of rubisco subunits in maize mesophyll cells does not overcome barriers to cell type-specific accumulation. Plant physiology 160, 419-432.

Feiz, L., Williams-Carrier, R., Wostrikoff, K., Belcher, S., Barkan, A., and Stern, D.B. (2012). Ribulose-1,5-bis-phosphate carboxylase/oxygenase accumulation factor1 is required for holoenzyme assembly in maize. Plant Cell 24, 3435-3446.

Johnson, X., Wostrikoff, K., Finazzi, G., Kuras, R., Schwarz, C., Bujaldon, S., Nickelsen, J., Stern, D.B., Wollman, F.A., and Vallon, O. (2010). MRL1, a conserved Pentatricopeptide repeat protein, is required for stabilization of rbcL mRNA in Chlamydomonas and Arabidopsis. Plant Cell 22, 234-248.

Wostrikoff, K., and Stern, D. (2007). Rubisco large-subunit translation is autoregulated in response to its assembly state in tobacco chloroplasts. Proc Natl Acad Sci U S A 104, 6466-6471.

 

For more information on host lab, click here: http://www.ibpc.fr/UMR7141/en/home/