PI: Prof. Kun Zang, PhD

Group Members: Dr. Xiaomei Xu

PhD students: Yongyin Liu

Postgraduate students: Yaoju Fan, Xiangyu Wen

Intern: Qi Ye

Research Interests of Our Group

Photosynthesis is the most fundamental biochemical process on Earth, using solar energy to convert CO₂ and water into carbohydrates and release oxygen. Plants, cyanobacteria, and eukaryotic algae collectively fix hundreds of billions of tons of CO₂ annually through photosynthesis. The enzyme responsible for CO₂ fixation is ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). However, Rubisco has low carboxylation efficiency and catalyzes a side reaction with O₂, triggering photorespiration, which consumes energy and releases fixed CO₂. Rubisco is therefore a key factor limiting photosynthetic efficiency. Unlike plants, cyanobacteria and eukaryotic algae have evolved a highly efficient photosynthetic carbon-fixation system—the CO₂ concentrating mechanism (CCM).

The cyanobacterial CCM consists of inorganic carbon (CO₂/HCO₃⁻) transporters on the cell membrane and carboxysomes. The carboxysome, the core carbon-fixing organelle, uses a selectively permeable protein shell to encapsulate Rubisco and carbonic anhydrase. O₂ and CO₂ cannot pass through the protein shell, while HCO₃⁻ enriched in the cytoplasm by inorganic carbon transporters can enter the carboxysome and is converted into CO₂ by carbonic anhydrase. The CO₂ cannot escape and is thus highly enriched, significantly enhancing the carbon-fixation efficiency of Rubisco.

Our group currently focuses on the assembly mechanisms and engineering applications of cyanobacterial carboxysomes:

1. Elucidating the mechanisms of liquid–liquid phase separation (LLPS)-mediated carboxysome assembly, and exploring functional reconstitution in plant chloroplasts to transplant the complete cyanobacterial CCM into higher plants, thereby improving photosynthetic carbon-fixation efficiency.

2. Engineering carboxysome-like protein-based organelles for enclosing multi-enzyme cascade pathways, or for encapsulating and protecting oxygen-sensitive reactions (e.g., nitrogenase, hydrogenase), to improve metabolic reaction efficiency and eventually construct artificial protein-based organelles with custom-designed functions.