Researchers from the University of Adelaide’s School of Agriculture, Food and Wine have shattered conventional wisdom about aquaporins, the membrane proteins responsible for transporting water through plant cells. Until now, it was widely believed that aquaporins exclusively facilitated the movement of water and not larger molecules such as sucrose.
In a groundbreaking study published in the Journal of Biological Chemistry, the team, led by Professor Maria Hrmova, observed sucrose transport in aquaporins for the first time, challenging established theories and expanding our understanding of their role in plant biology.
The study focused on HvNIP2;1, a Nodulin 26-like Intrinsic Protein found in barley, employing a multidisciplinary approach that included nanobiotechnology, electrophysiology, protein chemistry, protein modeling, and computational chemistry. The team integrated vast experimental and theoretical data, exploring approximately 3,000 aquaporins through phylogenomics.
HvNIP2;1, distinct from other aquaporin sub-clades, displayed altered structural characteristics that enabled the transport of saccharides. The researchers are now intrigued by its potential functions and its relevance to in planta function.
Professor Hrmova explained, “Full-scale steered molecular dynamics simulations of HvNIP2;1 and a structurally divergent spinach aquaporin revealed potential rectification of water, boric acid, and sucrose, setting the stage for future investigations.”
Co-author Professor Steve Tyerman emphasized the need to reconsider assumptions about aquaporins. “This work exemplifies that we need to be more open-minded about what different aquaporins may permeate, besides water,” he said, citing the possibility that some aquaporins may co-transport water and other molecules through a variety of protein-ligand interactions.
The properties of aquaporins play a crucial role in plant survival, mediating water and nutrient uptake, governing solute distribution, removing toxins, and recycling valuable sugars. This breakthrough discovery not only challenges preconceived notions but also has significant implications for bioengineering, offering the potential to design novel proteins with improved characteristics, including substrate specificity, thermostability, and folding.
Professor Hrmova concluded, “Understanding aquaporin properties is vital for agricultural biotechnology. By targeting aquaporins and other membrane transporters, we can enhance nutrient contents, exclude toxic elements, and ultimately improve crop quality and sustained food production.”