Alexzandria Sheppard
Alexzandria Sheppard headshot
Year: 2023
Faculty Advisor: Miguel Pineros

Structural-Functional Study of a Rice Potassium Transporter

High salinity negatively affects crop productivity and yield, making plant adaptations to salinity of high agronomic interest. High-affinity potassium transporters (HKTs) are a class of plasma membrane proteins that underlie plant responses to sodium and potassium salts. OsHKT2;2 is an HKT found in the roots of Oryza sativa (rice). Previous research suggests OsHKT2;2 subunits oligomerize to form a functional protein complex, predominantly existing as a homodimer. This project focuses on identifying the potential residues underlying the salt bridges and hydrogen bonds hypothesized to facilitate OsHKT2;2 subunit interactions. For this purpose, we generated OsHKT2;2 with specific residue substitutions and tested if these structural alterations resulted in a loss of protein-protein interaction, as determined via bimolecular fluorescence complementation (BiFC) in N. benthamiana. Using two-electrode voltage clamp (TEVC) in X. laevis oocytes expressing the various proteins, we tested if the disruptions in protein-protein interaction resulted in a loss of OsHKT2;2 functionality. Determining the basis of the oligomerization of OsHKT2;2 provides a basis to understand the structure-function relations governing its functionality. Given the important role HKTs play in mediating salt tolerance in plants, we anticipate this work will assist in the development of salt-tolerant crops through molecular breeding techniques, targeting HKT variants that confer growth and productivity advantages in high salinity environments.

My ten weeks interning at BTI and the Piñeros lab gave me insights into graduate school, new laboratory skills, and the opportunity to network with students and faculty. This research-focused experience gave me a better sense of the daily work and responsibilities of a graduate student. The longer, uninterrupted hours of lab work allowed me to learn new skills in cell and molecular biology while having the unique opportunity to interact in a multicultural environment. Outside of the lab, I was able to build connections with other students in my cohort along with faculty members at both BTI and Cornell. Overall, this REU has been highly beneficial in cementing my decision to pursue graduate school, shaping and preparing my future aspirations for a PhD program.