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. 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. This process, called phosphorylation, is used to initiate a number of activities, including cell movement, muscle movement and the metabolization of glucose.
Acetate kinase is found in microbes of the bacteria and archaea domains.
It plays a role in communication between different types of bacteria and performs a dual role in converting organic matter to methane. While some bacteria use it as the last energy-generating step in the breakdown of complex molecules, other bacteria use the acetate kinase to create new metabolites. This cooperative process, with one organism carrying out part of the metabolism and a second organism doing another part, illustrates how early bacteria may have evolved together to undertake complex tasks. And that cooperation continues through this very day. The determination of the structure of acetate kinase confirms the earlier prediction by Sanders and Hasson that the structure of acetate kinase would closely resemble those of other enzymes such as actin, used for muscle movement, and hexokinase, which is used to metabolize glucose.