Price Group - The cyanobacterial CO2 concentrating mechanism and the use of synthetic biology to transfer it to C3 crop plants

The Price lab is presently focusing on the molecular biology and physiology of photosynthesis in cyanobacteria (blue-green photosynthetic bacteria) with emphasis on gaining a full understanding of the adaptive mechanism known as a the 'CO2 concentrating mechanism' in these organisms. The CCM operates to elevate the CO2 concentration around the otherwise substrate-limited primary carboxylase, Rubisco, thus improving the efficiency of photosynthetic CO2 fixation. The system features inducible and constitutive transporters for CO2 and HCO3- that actively accumulate HCO3- within the cell through a light-dependent process. Accumulated HCO3- then enters a unique polyhedral Rubisco-containing organelle known as a carboxysome. Here CO2 is generated and maintained at a high steady state concentration with the aid of a carbonic anhydrase enzyme that is specifically located in the carboxysome. In addition, a special property of the carboxysome retards CO2 leakage leading to efficient CO2 fixation. We have produced a suite of defined CCM mutants for intensive analysis. Combined with the existence of several complete genome sequence databases for cyanobacteria, plus some modern molecular techniques, we have some powerful resources available for the molecular elucidation of the CCM. A present goal of this work is to allow the engineering of some useful CCM components into higher plants so that water and nitrogen-use efficiency can be improved.

  • Synthetic biology approaches to understanding mechanisms of inorganic carbon uptake.
  • Transfer of CCM genes to plant chloroplasts (RIPE project) to improve photosynthetic CO2 fixation efficiency.
  • Synthetic biology approaches to building carboxysomes in foreign hosts.
  • Proteomic analysis of protein complexes using protein mass spectrometry.
  • Physiological analysis of photosynthetic fluxes using Membrane-inlet mass spectrometry (MIMS).
  • Structure-function analysis of bicarbonate transporters.
  • Construction and Analysis of specific deletion and insertional mutants; bioinformatics and phylogenetics.
  • Engineering of plants with altered gene expressions used for testing for bottlenecks in photosynthesis.

 

More information on RIPE projects   http://ripe.illinois.edu/

More information on ARC Centre for Translational Photosynthesis projects http://photosynthesis.org.au/

 

 

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Selected publications

  • Wang H, Yan X, Aigner H, Bracher A, Nguyen ND, Hee WY, Long BM, Price GD, Hartl FU, Hayer-Hartl M (2019) Rubisco condensate formation by CcmM in β-carboxysome biogenesis. Nature 566 (7742): 131-5.
  • Kaczmarski JA, Hong N-S, Mukherjee B, Wey LT, Rourke L, Förster B, Peat TS, Price GD, Jackson CJ (2019) Structural Basis for the Allosteric Regulation of the SbtA Bicarbonate Transporter by the PII-like Protein, SbtB, from Cyanobium sp. PCC7001. Biochemistry 58: 5031-39.
  • Price GD, Long BM, Förster B (2019) DABs accumulate bicarbonate. Nature Microbiology 4: 2029-2030
  • Long BM, Hee WH, Sharwood RE, Rae BD, Sarah S, Lim Y-L, Nguyen ND, Massey B, Bala S, von Caemmerer S, Badger MR and Price GD (2018) Carboxysome encapsulation of the CO2-fixing enzyme Rubisco in tobacco chloroplasts. Nature Communications 9: 3570.
  • Rae BD, Long BM, Förster B, Nguyen ND, Atkinson N, Velanis CN, Hee WY, Mukherjee B, Price GD, and McCormick AJ (2017) Progress and challenges of engineering a biophysical carbon dioxide concentrating mechanism into higher plants. Journal of Experimental Botany 68: 3717-37.
  • Tolleter D, Chochois V, Poiré R, Price GD and Badger MR (2017). Measuring CO2 and HCO3- permeabilities of isolated chloroplasts using a MIMS-18O approach. Journal of Experimental Botany 68: 3915-24.
  • Pengelly JJL, Forster B, , von Caemmerer S, Badger MR, Price GD, Whitney SM (2014) Transplastomic integration of a cyanobacterial bicarbonate transporter into tobacco chloroplasts. Journal of Experimental Botany 65:3071-80
  • Whitehead L, Long BM, Price GD and Badger MR (2014) Comparing the in vivo function of α- and β-carboxysomes in two model cyanobacteria. Plant Physiology 165: 398-411.
  • Rae BD, Long BM, Whitehead LF, Forster B, Badger MR and Price GD (2013) Cyanobacterial carboxysomes: micro-compartments that facilitate CO2 fixation (Invited review). Journal of Molecular Microbiology and Biotechnology 23(4-5): 300-307
  • Price GD, Pengelly JJL, Forster B, Du J, Whitney SM, von Caemmerer S, Badger MR, Howitt SM, Evans JR. (2013) The cyanobacterial CCM as a source of genes for improving photosynthetic CO2 fixation in crop species (Invited Review). Journal of Experimental Botany 64: 753-68.
  • Rae BD, Long BM, Badger MR and Price GD (2013) The function, composition and evolution of the two types of carboxysomes: polyhedral micro-compartments that facilitate CO2 fixation in cyanobacteria and some proteobacteria. (Invited Review). Microbiology and Molecular Biology Reviews 77: 357-359
  • Rae BD, Long BM, Badger MR and Price GD (2012) Structural determinants of the outer shell of b-carboxysomes in Synechococcus elongatus PCC 7942: Roles for CcmK2, K3-K4, CcmO, and CcmL. PlosOne 7: e43871.
  • Price GD, Badger MR, von Caemmerer S (2011) The prospect of using cyanobacterial bicarbonate transporters to improve leaf photosynthesis in C3 crop plants (Invited Focus Issue). Plant Physiology.
  • Price GD, Howitt SM (2011) The cyanobacterial bicarbonate transporter, BicA: its physiological role and the implications of structural similarities with human SLC26 transporters (Invited review). Biochemistry and Cell Biology 89: 178-188.
  • Price GD (2011) Inorganic carbon transporters of the cyanobacterial CO2 concentrating mechanism (Invited Review). Photosynthesis Research 109: 47-57.
  • Rae BD, Förster B, Badger MR and Price GD (2011) The CO2-concentrating mechanism of Synechococcus WH5701 is composed of native and horizontally-acquired components. Photosynthesis Research 109: 59-72.
  • Long BM, Rae BD, Badger MR and Price GD (2011) Over-expression of the β-carboxysomal CcmM protein in Synechococcus PCC7942 reveals a tight co-regulation of carboxysomal carbonic anhydrase (CcaA) and M58 content. Photosynthesis Research 109: 33-45.
  • Price GD, Shelden MC, Howitt SM (2011) Membrane topology of the cyanobacterial bicarbonate transporter, SbtA, and identification of potential regulatory loops. Molecular Membrane Biology. 28: 265-275.
  • Shelden MC, Howitt SM, Price GD (2010) Membrane topology of the cyanobacterial bicarbonate transporter, BicA, a member of the SulP (SLC26A) family. Molecular Membrane Biology. 27: 12-23. (Figure 2 selected for the cover page of issue 27-1).
  • Long BM, Tucker L, Badger MR and Price GD (2010) Functional Cyanobacterial b-Carboxysomes Have an Absolute Requirement for Both Long and Short Forms of the CcmM Protein1. Plant Physiology. 153: 285–293.

 

PS Webinar Series: PhD Exit Seminar - Putting Rubisco into a carboxysome.

Event | Fri 11 December 2020
This thesis aimed to resolve how cyanobacterial Rubisco interacts with its binding partners both in vivo and in vitro.
Seeing the light: Better plants, better future

Seeing the light: Better plants, better future

Story | Wednesday 3 February 2021
Increasing food production is one of the greatest challenges of the 21st century. The Australian Academy of Science has produced a video featuring researchers who are from the ARC Centre of Excellence for Translational Photosynthesis and the ANU Research School of Biology.
Blue-green algae promises to help boost food crop yields

How to put together a fast carbon-capturing engine: lessons from blue-green algae

Story | Thursday 24 January 2019
A scientific breakthrough intended to help boost the yields of food crops has solved a long-standing question of how cyanobacteria, known as blue-green algae, builds the carbon-capturing engines called carboxysomes in a protein liquid droplet formation.

Blue-green algae promises to help boost food crop yields

Story | Tuesday 4 September 2018
Scientists at ANU have engineered tiny carbon-capturing engines from blue-green algae into plants, in a breakthrough that promises to help boost the yields of important food crops such as wheat, cowpeas and cassava.
ANU research to help boost food production to feed the world

RSB research to help boost food production to feed the world

Story | Monday 18 September 2017
The Australian National University (ANU) will help to boost food production to feed a rapidly growing world population as part of a major international research collaboration supported by tens of millions of dollars in new funding.
Architectural representation of a carboxysome on the windows of the RSB Linnaeus building

Carboxysomes

Story | Thursday 13 April 2017
Carboxysomes are polyhedral protein micro-compartments in cyanobacteria which concentrate CO2 and increase the efficiency of carbon fixation. In 1993, RSBS researchers Dean Price, Murray Badger and Susan Howitt determined the genetic sequence encoding for the proteins that form the protein shell of a carboxysome.
Laura Wey

A university degree that helps put food on the table

Story | Thursday 21 July 2016
Laura Wey has used her undergraduate research experience at ANU to help grow a better future for us all.

Academic promotions: Level E Professor

Story | Monday 2 February 2015
Congratulations to the six RSB members who have been promoted to Level E Professor as of 1 January 2015.

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