West Lafayette, IN Scientists have traced a protein to the point in early evolution when it first began using a chemical, ATP, to power cells.

ATP, or adenosine triphosphate, powers the machinery of cells by releasing energy when its phosphate chemical bond is broken.

A study of the structure of an acetate kinase, an enzyme used in converting organic matter to methane, indicates that the enzyme may be the primordial, or earliest, protein to use ATP, say scientists at Purdue and Pennsylvania State universities.

"The structure, plus biochemical considerations about the early evolution of life, suggest we may be getting a snapshot of what a protein from the very origin of protein-based life looks like," says David Sanders, assistant professor of biological sciences at Purdue, who directed the study. "Acetate is very easily synthesized under early earth conditions from things like carbon monoxide and methane, which were present in high concentrations in early life."

The study, published in the Jan. 19 issue of the Journal of Bacteriology, provides science with a more complete picture of how proteins evolved and paints an image of very early cooperation between bacteria.

Understanding the structure also may someday lead to the ability to control the enzyme, Sanders says, noting that acetate kinase comes from a methane-producing bacterium and is responsible for one-third of the global methane, a greenhouse gas.

The structure also suggests that acetate kinase may be the common ancestor in a "superfamily" of enzymes known as phosphotransferases, named for their ability to make or break phosphate bonds in cells. This process, called phosphorylation, is used to initiate a number of activities, including cell movement, muscle movement and the metabolization of glucose.

The research was a collaborative effort among Sanders; Miriam Hasson, assistant professor of biological sciences at Purdue; and James G. Ferry, professor of biochemistry and mol
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Contact: Susan Gaidos
sgaidos@purdue.edu
765-494-2081
Purdue University
8-Mar-2001