Graduate Students Mini Symposium VI - 2023

13:15 h Elif Elcin - AG Sourjik

Investigating limits of protein interchangeability in chemotaxis system of Proteobacteria

It is still poorly understood how complex, multi-component macromolecular machinaries like chemotaxis system evolve over time while maintaining the network functionality. This study focuses on CheY protein which is a well conserved protein among bacteria and a core component of the chemotaxis pathway. By replacing the CheY protein with its ancient/modern homologs and using quantitative methods to describe chemotactic behavior we explore how functionality of a protein in this network decays over the range of evolutionary distances. This gives us an idea about the limits of protein interchangeability in chemotaxis system. Furthermore, we perform experimental evolution to regain the decay of protein function in the pathway.

13:45 h Yat Kei Lo - AG Schuller

Structure and mechanism of prokaryotic carbon-concentrating mechanisms

Carbon fixation is often limited by the scarce availability of dissolved inorganic carbon (DIC) in natural environment. To maintain a high intracellular DIC level, autotrophic bacteria utilize an arsenal of carbon-concentrating mechanisms (CCM), including the recently discovered Dissolved Inorganic Carbon-Concentrating Transporter (DIC-CT). Despite of its physiological significance, the molecular mechanism remains largely enigmatic. Here we present the first single particle analysis of DIC-CT together with structure guided mutagenesis. Our results suggest that DIC-CT might function as a novel class of proton motive force coupled vectorial carbonic anhydrase catalyzing CO₂ hydration.