By IANS
Washington : A certain kind of RNA is like a great historian – it preserves some of the earliest and most profound events of our evolutionary past in its unique structure.
The intermediaries between genes and proteins, RNAs, or ribonucleic acids, are “ancient” molecules and probably one of the most fundamental building blocks of life. They also link genes and proteins most directly, Sciencedaily reported.
A special kind of RNA – the transfer RNA, or tRNAs – downloads genes into chains of specific amino acids that make up proteins, with the help of a coded segment giving precise instructions for the process.
The notion that tRNAs lie at the core of protein building implies that it has been around for a long time, said Gustavo Caetano-Anollés, of the University of Illinois and co-author of the study.
His inquiry began with a hunch that understanding the structural properties of tRNA would shed light on how organisms and viruses evolved.
“Perhaps in evolution there are things that are so fundamental that they are kept, held onto, for millions or even billions of years,” Caetano-Anollés said.
“Those are the fossils, the molecular fossils, that tell us about the past. Therefore, studying these molecules can address fundamental questions in biology and evolution.”
All tRNAs assemble themselves into a shape which, when flattened, resembles a clover leaf. The team began by looking for patterns in this clover-leaf structure, using detailed data from hundreds of molecules representing viruses and each of the three super-kingdoms of life: archaea, bacteria and eukarya.
The researchers converted all distinguishing features of the individual tRNA clover-leaf structures into coded characters, a process that allowed a computerised search for the simplest tRNA family tree.
They conducted the same analysis on the tRNAs of each of the super-kingdoms, to see how far these groupings diverged from the overall tree. This comparison allowed them to determine the order in which viruses and each of the super-kingdoms diverged.
The new analysis supports an earlier study, which Caetano-Anolles also led, suggesting that archaea, microbes that can survive in near boiling acid, were the first to arise as an evolutionarily distinguishable group.
Caetano-Anollés said: “Those are the fossils, the molecular fossils, that tell us about the past. Therefore, studying these molecules can address fundamental questions in biology and evolution.”