Functionality of a grapevine transport protein defined
Researchers in the School of Agriculture, Food & Wine have discovered that a protein which mediates the transport of alkali metal ions, such as potassium, and halides ions across plant membranes acts similarly to a protein found in animals.
Grapevine CCC protein (in two nearly orthogonal orientations) transports potassium (purple) and chloride (green) ions through the pore (black dots) in an electroneutral fashion. Credit: Maria Hrmova.
The protein is a cation-chloride cotransporter (CCC), and these are present in all cellular life forms. Some CCCs are able to transport two types of ions, both potassium and halide chloride, while others can also transport a third – sodium.
The selectivity of plant CCCs has been controversial, and it was previously understood that they are sodium-potassium-chloride symporters. However, University of Adelaide researchers found that a range of plants, such as grapevine, tobacco, rice, pumpkin, barrel clove, and green algae have two-ion CCCs, similar to those which are found in animals.
“We showed that the structural signatures of ion binding sites in grapevine CCC resemble those of animal potassium-chloride symporters,” said Professor Maria Hrmova, who previously worked on plant transport proteins.
“Our findings widen the role of plant CCC proteins in plant biology and will have implications for the bioengineering of plants for food production and plant survival. This will be the subject of future studies.
“Understanding the properties of these transporters at the molecular level is important for bioengineering to design novel proteins with improved characteristics, such as permeation selectivity, thermostability, and folding.”