Spencer undertook his BSc (Botany, Biochemistry and Chemistry) honours and PhD at James Cook University of North Queensland that revealed unique molecular and biochemical features of the photosynthetic CO2-fixing enzyme, Rubisco, in the symbiotic marine microalgae of corals and clams. In 1996 he moved to ANU to begin his postdoctoral studies and expanded his interest in interrogating Rubisco biology using plastome transformation biotechnology. His pivotal work on modifying plant photosynthesis via Rubisco engineering led to him being awarded the Goldacre Award in 2002 from the Australian Society of Plant Scientists and an International Photosynthesis Congress Young Scientist Award in 2004. From 2004-09 he held an ARC Research Fellowship and in 2009 was awarded an ARC Future Fellowship.
Improving plant CO2 capture and growth efficiency.
My research focuses on utilising novel biotechnological tools to scrutinize the biology of the biospheres most abundant protein, the photosynthetic CO2-fixing enzyme Rubisco (ribulose-1,5-bisphosphate carboxylase/oxygenase). The research provides training in molecular biology, protein engineering (directed evolution), enzyme kinetics, biochemistry, plastome transformation, tissue culture, measuring leaf photosynthesis and plant growth.
Despites Rubisco’s pivotal role in photosynthetic carbon assimilation – catalysing the primary step of incorporating CO2 into carbohydrates that are used to store and transport energy - it is surprisingly an inefficient enzyme in need of improvement. It constitutes about 20 to 30% of soluble leaf protein due to its inefficiency. The catalytic inadequacies of Rubisco (such as a slow turnover rate and poor ability to distinguish CO2 from O2) frequently limit the growth capacity of many plants, including most crops. As such, Rubisco has been studied intensively as a prime target for genetic engineering as a means to supercharge photosynthesis and improve growth efficiency. Towards this significant challenge, the primary foci of research in the Whitney laboratory utilises recent technological and conceptual breakthroughs to study Rubisco biogenesis, modify its catalysis, understand its regulation by Rubisco activase and generally tackle the challenges faced in developing strategies for enhancing Rubisco activity to improve plant productivity.
- Rubisco for all climates: unlocking the enzyme’s structure-function relations for more efficient photosynthesis.
ARC Discovery project (2012-2014)
- Enhancing plant photosynthesis by engineering the CO2-fixing enzyme Rubisco.
ARC Future Fellowship (2009-2013)
- Identifying potential barriers to transplanting modified forms of the CO2-fixing enzyme, Rubisco, into plants.
ARC Discovery project (2009-2011)
- Practical strategies for engineering the CO2-fixing enzyme, Rubisco, whose subunits are encoded in different subcellular compartments.
ARC Research Fellowship (2004-2009).
General papers on Rubsico
- Whitney S.M., Houtz R.L and Alonso H (2011) Advancing our understanding and capacity to engineer nature’s CO2 sequestering enzyme, Rubisco. Plant Physiology 155, 27-35
- Andrews, T.J. and Whitney, S.M. (2003) Manipulating rubisco in the chloroplasts of higher plants. Archives of Biochemistry and Biophysics 414: 159-169
Directed evolution of Rubisco
- Mueller-Cajar and Whitney S.M. (2008) Directing the evolution of Rubisco and Rubisco activase - first impressions of a new tool for photosynthesis research. Photosynthesis Research, 98, 667-675
- Mueller-Cajar and Whitney S.M. (2008) Evolving improved Synechococcus Rubisco functional production in Escherichia coli. Biochemical Journal,414, 201-214
- Mueller-Cajar O, Morell M, Whitney S.M. (2007) Directed evolution of Rubisco in E. coli reveals a specificity-determining hydrogen bond in the Form II enzyme. Biochemistry, 46, 14067-74
- Greene D.N, Whitney S.M, Matsumura I. (2007) Artificially evolved Synechococcus PCC6301 Rubisco variants exhibit improvements in folding and catalytic efficiency. Biochemical Journal, 404, 517-24.
Engineering of Rubisco and Rubisco activase
- Whitney, S.M Sharwood, R.E, Orr, D White, S.J, Alonso, H and Galmes, J (2011) Isoleucine 309 acts as a C4 catalytic switch that increases ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) carboxylation rate in Flaveria. Proceedings of the National Academy of Sciences 108, 14688-14693.
- Blayney, M, Whitney, S.M and Beck, J 2(011) NanoESI mass spectrometry of Rubisco and Rubisco activase structures and their interactions with nucleotides and sgar phosphates'. Journal of the American Society for Mass Spectrometry 22, 1588-1601.
- Alonso H, Blayney M.J, Beck J.L and Whitney S.M (2009) Substrate induced assembly of Methanococcoides burtonii D-Ribulose-1,5-Bisphosphate carboxylase/oxygenase dimers into decamers. Journal of Biological Chemistry 284, 33876-82
- Whitney S.M and Sharwood R.E (2008) Construction of a tobacco master line to improve Rubisco engineering in chloroplasts. Journal of Experimental Botany 59, 1909-1921
- Sharwood R.E, von Caemmerer S, Maliga P and Whitney S.M. (2008) The catalytic properties of hybrid Rubisco comprising tobacco small and sunflower large subunits mirror the kinetically equivalent source Rubiscos and can support tobacco growth. Plant Physiology 146, 83-96
- Whitney, S.M and Sharwood R.E (2007). Linked Rubisco subunits can assemble into functional oligomers without impeding catalytic performance. Journal of Biological Chemistry 282, 3809-3818
- Whitney, S.M. and Andrews, T.J. (2003) Photosynthesis and growth of tobacco with a substituted bacterial Rubisco mirror the properties of the introduced enzyme Plant Physiology 133, 287-294
- Whitney, S.M. and Andrews, T.J (2001) Plastome-encoded bacterial ribulose-1,5-bisphosphate carboxylase/oxygenase (RubisCO) supports photosynthesis and growth in tobacco. Proceeding of the National Academy of Sciences 98: 14738-14743.
- Whitney, S. M. and T. J. Andrews (2001) The gene for the ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) small subunit relocated to the plastid genome of tobacco directs the synthesis of small subunits that assemble into Rubisco. Plant Cell 13: 193-205.