Transfer RNA transforms tree of life

A comparison of transfer RNAs has revealed the roots of the tree of life, indicating ancient origins for Archaea and viruses, according to research published yesterday in linkurl:PLoS Computational Biology.;http://www.ploscompbiol.org/article/info%3Adoi%2F10.1371%2Fjournal.pcbi.1000018 Since the discovery that ribosomal RNA can reveal evolutionary relationships between organisms, researchers have split the universal tree of life into three main branches: the superkingdoms Archaea, Bacteria, and Eukarya. But the root of the tree has remained linkurl:controversial.;http://www.the-scientist.com/article/display/13255/ Also, this tripartite tree of "life" has omitted viruses, which have long been considered as "not living." To resolve the timeline of diversification and the origin of viruses, therefore, a new molecular marker was needed. Enter tRNA. "Transfer RNAs are ancient molecules," said Gustavo Caetano-Anollés of the University of Illinois at Urbana-Champaign. "They're molecular fossils." Caetano-Anollés and his colleague Feng-Jie Sun investigated the sequence and structure of hundreds of tRNAs to probe for deep evolutionary relationships in the tree of life....