With proteins, shape is everything. The correct shape allows some proteins to ferry atoms or molecules about a cell, others to provide essential cellular scaffolding or identify invading bacteria for attack. When proteins lose their shape due to high temperature or chemical damage, they stop working and can clump together- a hallmark of Parkinson's and Alzheimer's.
The University of Wisconsin-Madison researchers have discovered another stress that decreases protein stability and causes clumping: a shortage of zinc, an essential metal nutrient.
Zinc ions play a key role in creating and holding proteins in the correct shape. In the study, Colin MacDiarmid and David Eide showed that the gene Tsa1 creates "protein chaperones" that prevent clumping of proteins in cells with a zinc shortage. By holding proteins in solution, Tsa1 prevents damage that can otherwise lead to cell death.
For simplicity, the researchers studied the system in yeast- a single-celled fungus. Yeast can adapt to both shortages and excesses of zinc, MacDiarmid said.
Cells that are low in zinc also produce proteins that counter the resulting stress, including one called Tsa1.The researchers already knew that Tsa1 could reduce the level of harmful oxidants in cells that are short of zinc.
"In yeast, if a cell is deficient in zinc, the proteins can mis-fold, and Tsa1 is needed to keep the proteins intact so they can function. If you don't have zinc, and you don't have Tsa1, the proteins will glom together into big aggregations that are either toxic by themselves, or toxic because the proteins are not doing what they are supposed to do. Either way, you end up killing the cell," Eide said.
While the medical implications remain to be explored, there are clear similarities between yeast and human cells.
The study published in the online Journal of Biological Chemistry.
--ANI (Posted on 02-10-2013)