Dr Laura Gunn (Dept. of Cell and Molecular Biology, Uppsala University)
Thu 10 Oct 2019, 12:00 - 13:00
C.H Waddington Building, Seminar room 1.08, King's Building's

If you have a question about this talk, please contact: Julie Fyffe (jfyffe)

Image for Structural studies of Rubisco: are we flogging a dead horse?

The CO2-fixing enzyme Ribulose-1,5-carboxylase/oxygenase (Rubisco) represents the major point of carbon entry into the biosphere. Rubisco has a slow catalytic rate and exhibits poor substrate specificity such that Rubisco catalysis often limits the growth rate of photosynthetic organisms and, accordingly, Rubisco catalysis is a major engineering target to boost crop yield. Rubiscos from higher plants are comprised of eight catalytic large- (LSu) and eight auxillary small- (SSu) subunits, which form a ≈ 550 kDa L8S8 hexadecamer. Despite there being over 80 Rubisco structures deposited in the Protein Data bank, attempts to rationally engineer a more efficient Rubisco to boost crop performance have been, at best, underwhelming.

The overall structure is highly conserved amongst plant Rubiscos. Rubisco structures fail to provide predictive insights into why single point mutations distant from the catalytic site often dramatically impair enzyme function and, similarly, what minor structural variation might translate to kinetic improvements. While the first crystal structures provided key information about Rubisco architecture and gave mechanistic insights, can we garner meaningful insights from static images of yet more Rubiscos that, quite frankly, look just like all the others?

 Dr. Gunn argues that structural biology in the context of Rubisco is not dead. She will discuss her work producing Rubisco structures from archaea, algae and higher plants, and the surprising answers you can get, if only you ask the right questions. These answers reveal novel structure-function, appreciation of the Rubisco biogenesis pathway and new insights into the Rubisco catalytic mechanism. She will also briefly discuss current and future structural biology technologies, including CryoEM and Xray fee-electron lasers.