Biological Sciences Colloquium: Dr. Shan He

Shan He, Ph.D., Assistant Professor, Department of Botany, University of Wisconsin – Madison, will present a talk about her work entitled, ‘Structure and regulation of the CO₂-concentrating organelle, the pyrenoid’

The Abstract is as Follows:

Approximately one-third of global CO₂ fixation occurs in an algal organelle, the pyrenoid. Engineering the pyrenoid into crops has great potential to increase yields. The pyrenoid enhances photosynthesis by clustering the CO₂-fixing enzyme Rubisco into a dynamic liquid-like condensate and supplying it with concentrated CO₂. A molecular understanding of pyrenoid biogenesis and regulation will facilitate the engineering of the pyrenoid and shed light on how the pyrenoid plays such an important role in the global carbon cycle. However, both the structural basis of the pyrenoid condensate and how its phase separation is regulated were unknown. In my talk, I will share our structural characterization of how the pyrenoid condensate is formed by a linker protein that clusters multiple Rubisco holoenzymes, which reveals a critical motif that mediates the assembly of the pyrenoid’s three sub-compartments. Furthermore, I will discuss our discovery and characterization of a protein kinase that regulates the size and number of the pyrenoid condensate through disrupting phase separation. Our findings advance the structural and regulatory understanding of the pyrenoid, paving the way for its engineering into crops. More broadly, our work makes the pyrenoid a powerful model for studying biological and biophysical mechanisms of biomolecular condensates in cell biology.

The presentation will begin at 3:00 PM in Lapham Hall N101, preceded by an informal reception from 2:45 – 3:00PM.