High concentrations of boric acid in soils adversely affect cereal crop production worldwide. Solution to such problem lies in developing variants of transport proteins that can improve plant tolerance to high soil boric acid. However, the underlying molecular mechanisms of such transport proteins are largely unknown. This research work addresses such mechanisms using first computational model for a barley efflux transport protein HvBot1, which we corroborated by biochemical, biophysical and electrophysiology measurements. The challenges in computational modeling typically include predictions of a tertiary structure in the absence of prior experimental information, obtainable by X-ray crystallography, electron microscopy or NMR spectroscopy. After in silico refinement of a wild type tertiary structure, we performed structural mutations to study relative ion permeation dynamics. We correlated ion residence time inside the protein to its transport capability and established the effect of mutations on the mobility of ions, and how this affected resident ion hydration states. A profile of biologically relevant ion channels inside protein was also calculated. The need for such multi-scale modeling is to provide molecular insights and solutions to develop genetically superior cereal crops that will ensure sustainable food production in diverse soil environments. Based on our findings, we suggest that HvBot1 be designated as a channel-like Na+-dependent anion transporter with a high affinity for borate anions.

When in silico meets in vitro: Molecular basis of function of an anion-permeable efflux transporter from barley (Hordeum vulgare L.)

251st National Meeting (2016)

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