Protein shields for dehydration

Many species have the ability to withstand long bouts of dehydration. New findings from Sohini Chakrabortee, Alan Tunnacliffe (University of Cambridge, UK), and colleagues reveal that a family of water-loving proteins in these organisms protects the cell from desiccation-induced protein aggregation.

Desiccation-tolerant organisms as diverse as bacteria, brine shrimp, and plants have in common a family of hydrophilic proteins known as the LEA proteins, which are necessary for survival in dry times. In the new report, a worm LEA protein is shown to inhibit aggregation of the entire worm and human proteomes during desiccation in vitro. It also prevented the aggregation that accompanies rehydration. “That experiment was a watershed,” says Tunnacliffe. “It means the proteins also work in the hydrated states.”

In fully hydrated human cells, a LEA protein hindered aggregation of polyQ-containing proteins. It also improved the cells' ability to tolerate high salt levels, which mimic mild dehydration.

Unlike chaperones, which have defined structures, LEA proteins are natively unfolded. “Because they don't have any structure,” says Tunnacliffe, “they don't aggregate.” This property might allow them to work like a molecular shield, coating aggregation-prone proteins and hindering them from interacting with others of their kind.

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