. Author manuscript; available in PMC: 2013 Aug 1.

Published in final edited form as: Curr Opin Chem Biol. 2012 May 29;16(3-4):337–344. doi: 10.1016/j.cbpa.2012.05.002

Table 1.

Strategies towards enhanced carbon fixation

Target	Relevant pathway(s)	Modification	Approach	Refs
Light-gathering efficiency	All light-dependent carbon fixation pathways	Reduced antenna size	Chlorophyll/pigment synthesis knockout or downregulation	(35, 42)
Light-gathering efficiency	All light-dependent carbon fixation pathways	Expand wavelength usage	Heterologous expression of alternative chlorophylls and phycobilins	(11, 50)
Carbon concentrating mechanisms	CO2-utilizing pathways	Carboxysome	Expression of carboxysomes in chloroplasts	(9)
	CO2-utilizing pathways	Novel scaffold design	Construction of novel subcellular compartments using synthetic RNA or protein scaffolds	(12, 14)
	Alternative and synthetic carbon fixation pathways	Alternative carboxylating enzymes	Use of carboxylating enzymes dependent on bicarbonate in alkaline environments	(4, 15)
Carboxylating reactions	Calvin Cycle	Faster RuBisCO activity	Heterologous expression of high-activity, low specficity RuBisCOs in CO2-rich environments	(45, 50)
	3-HOP, HB/HP	Decreased oxygen sensitivity	Reconstruction of naturally oxygen-tolerant carbon-fixation pathways in industrially-relevant species	(4, 10, 48)
	Synthetic carbon fixation pathway	Improved specificity & activity	Use of non-canonical carboxylating enzymes (e.g. PEP carboxylase, pyruvate carboxylase)	(3)
Electro-synthesis	Anaerobic carbon-fixation pathways	Acceptance of electrons from cathode	Expression of outer membrane electron donor/acceptor complexes	(22, 29, 36)