Seminar: Hussam Hassan Nour-Eldin: How to deorphanize orphan transporters? A novel untargeted extract-based approach paves the way
Asc. Prof. Hussam Hassan Nour-Eldin, Section for Molecular Plant Biology, Copenhagen University
Oplysninger om arrangementet
MBG Auditorium (1871-120)
The Nitrate and Peptide transporter Family (NPF) is found in all plants. Despite what its name indicates, this family plays a multitude of essential roles in plants, for example, in controlling the spatiotemporal distribution patterns of defense compounds and phytohormones as well as in delivering micronutrients and sugar to seeds. However, the vast majority of NPF members in plants remain uncharacterized, which raises the intriguing question: What other roles are members of this family involved in? Moreover, from a structural perspective we know little about how members of this family bind and distinguish between substrates with such diverse chemical structures.
To address the first question, we are developing an untargeted extract-based de-orphanization approach, which I believe will become state-of-the-art in how we determine the substrates of transporters in the future. I will present the current state of the approach, our experiences in using it, and the challenges encountered.
To address the second question, we have adopted three NPF transporters, the glucosinolate transporters 1-3 (GTR1-3, AtNPF2.9-2.11) from Arabidopsis as a model system. GTR1-3 display overlapping yet distinct substrate specificities and the subclade is found in all cruciferous plants. Using a rational mutational approach, we have swapped the substrate specificity of GTR1 and GTR3 in a reciprocal manner through the simultaneous mutation of 7 residues within the substrate binding cavity. This gain-of-function approach provides novel insights into the residues involved in binding the variable side chain of the glucosinolates and represents a step forward in understanding the molecular determinants of substrate specificity in the NPF family.