BEIJING, Aug. 9 (Xinhuanet) -- Researchers resurrected 4-billion-year-old Precambrian proteins in the lab, and the protein is thought to have existed in single-celled organisms linked to the earliest ancestor of all life, according to a study in the journal Structure on Thursday.
The study report, written by Jose Sanchez-Ruiz of the University of Granada, said that the protein resurrected by scientists survives in the extreme environments of high acidity and temperature expected on early Earth.
By analyzing the protein’s X-ray crystal structures, researchers gained novel insights into protein evolution, which has revealed a remarkable degree of structural similarity among proteins since life first evolved on Earth.
Sanchez-Ruiz and his collaborators constructed a phylogenetic tree of protein sequences by analyzing the amino acid sequences of thioredoxins -- proteins found in organisms from the three domains of life, including bacteria, archaea and eukaryotes.
They found that present-day thioredoxin structures are remarkably similar to those that existed at a time close to the origin of life, even though their amino acid sequences are very different.
This finding supported a punctuated-equilibrium model of evolution in which protein structures remain constant over long time periods, with new changes occurring intermittently over short periods.
"In addition to uncovering the basic principles of protein structure evolution, our approach will provide invaluable information regarding how the 3D structure of a protein is encoded by its amino acid sequence," Sanchez-Ruiz said.