The function, evolution, and future of carboxysomes

Area of Science:

• Biochemistry
• Molecular Biology
• Photosynthesis Research

Background:

• Carboxysomes are protein-bound microcompartments central to cyanobacterial carbon fixation.
• They concentrate CO2 for the enzyme Rubisco, optimizing photosynthesis via CO2-concentrating mechanisms (CCMs).
• Cellular bicarbonate (HCO3-) accumulation is critical for carboxysome function.

Purpose of the Study:

• To review the historical advancements in understanding carboxysome structure, function, and biogenesis.
• To explore the evolutionary reasons for carboxysome absence in plants.
• To discuss the potential and challenges of engineering carboxysomes into plant chloroplasts.

Main Methods:

• Historical literature review and synthesis of research findings.
• Analysis of evolutionary trajectories and genetic basis for carboxysome presence/absence.
• Examination of physiological data and in vitro studies related to carboxysome function.

Main Results:

• Significant progress has been made in understanding carboxysome structure, assembly, and role in CCMs.
• Terrestrial plants lack carboxysomes despite a shared evolutionary past with cyanobacteria.
• Engineering carboxysomes into plant chloroplasts is a promising strategy to boost photosynthetic efficiency.

Conclusions:

• Carboxysomes represent a highly evolved system for carbon fixation, crucial for cyanobacteria.
• Overcoming challenges like bicarbonate accumulation is key for successful heterologous expression in plants.
• Future applications include using carboxysomes as platforms for enhanced carbon fixation and novel biocatalysis.