A Cautionary Synbio Tale: The Challenge of Assembling Better Rubiscos

With the human population expected to reach ten billion by 2025, it is increasingly pertinent to ensure our food security; for example, by improving agricultural productivity. One way to do so is to engineer crop plants by replacing their native Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) with a kinetically superior one. This is because though Rubisco is the gateway enzyme for carbon dioxide-fixation, it is also one of the major limiting factors of photosynthesis. Previously, a hornwort Rubisco (hRubisco) was found to be kinetically superior to crop plant Rubiscos, making it a promising candidate for improving crop productivity. However, Rubisco assembly is mediated by a series of specific assembly factors, which may not be compatible with a foreign Rubisco. Our research will explore the interactions between hRubisco and RbcX, an assembly factor from tobacco, a model plant for chloroplast transformation. This builds upon observations that the binding of hRbcX influences hRubisco’s assembly and kinetics. Through our research we hope to determine if hRubisco interacts with tobacco RbcX in a similar fashion using an E. coli synthetic biology system for expressing and assembling Rubisco. Subsequently, we will measure kinetics of purified Rubisco using an activity assay. We hypothesize that hRubisco will have increased kinetics when assembled without RbcXs like the established interactions between hRubisco and its cognate RbcXs. With our findings, we can make informed decisions to ensure that hRubisco functions optimally when introduced into tobacco and other crop plants, taking us one step closer to improving agricultural productivity and ensuring food security.

This summer I was able to learn about Rubisco and how synthetic biology systems can be used to answer research questions. I worked in the Gunn lab and had an amazing experience in a new lab setting and worked with motivated PhD students—I always felt very welcomed by their presence. My experience during this REU has made me even more excited as I begin to think about my remaining time in undergrad and beyond into graduate school. Building off of this summer, I look forward to exploring more paths and research in plant science.