Prions may be lurking in plants.
Prions are held responsible for Bovine Spongiform
Encephalopathy (BSE, or mad cow’s disease) and deadly Kreutsfeldt-Jacob disease
in humans.
A research team led by Susan Lindquist, a biologist at the
Whitehead Institute for Biomedical Research in Cambridge, Massachusetts, say
they found a section of protein in thale cress (Arabidopsis) that behaves like
a prion when it is inserted into yeast.
More research is required to determine
whether they are like prions that attack the brains of mammals.
In plants, the protein is called Luminidependens (LD), and
it is normally involved in responding to daylight and controlling flowering
time.
When a part of the LD gene is inserted into yeast, it
produces a protein that does not fold up normally, and which spreads this
misfolded state to proteins around it in a domino effect that causes aggregates
or clumps.
Later generations of yeast cells inherit the effect: their
versions of the protein also misfold.
This does not mean that plants definitely have prion-like proteins,
says Lindquist; but she thinks that it is likely.
“I’d be surprised if they weren’t there,” she says.
To prove it, researchers would need to grind up a plant and
see whether they could find a protein such as LD in several different folded
states, as well as show that any potential prion caused a misfolding cascade
when added to a test-tube of protein.
Lindquist adds that because she’s not a plant scientist —
her focus is on using yeast to investigate prions — she hasn’t tried
these experiments.
The study appeared Apr. 25 in the Proceedings of the
National Academy of Sciences.
